Biology term index:  Related glossaries include Biologics   Chemistry   Drug discovery & development   Drug discovery informatics   Drug & disease targets    

active center: The location in an enzyme where the specific reaction takes place. IUPAC Bioinorganic

agonist(s): An endogenous substance or a drug that can interact with a receptor and initiate a physiological or a pharmacological response characteristic of that receptor (contraction, relaxation, secretion, enzyme activation, etc.) IUPAC Medicinal Chemistry] Contrast with antagonist(s).

analog: A drug whose structure is related to that of another drug but whose chemical and biological properties may be quite different. IUPAC Medicinal Chemistry

antagonist: A drug or a compound that opposes the physiological effects of another. At the receptor level, it is a chemical entity that opposes the receptor- associated responses normally induced by another bioactive agent. IUPAC Medicinal Chemistry Compare agonist. Related term: selective modulators

antigens: Substances that are recognized by the immune system and induce an immune reaction. MeSH

antisense: Many scientists are still confused by the terms ‘sense’ and antisense’ when referring to DNA because the terminology has changed over the years. Because there are good logical threads that allow one to rationalize how each strand could be designated as the sense strand of DNA, the terms become intrinsically confusing…It became apparent that Richard Moldwin’s rmoldwin@midway.uchicago.edu proposal is probably the best solution to the problem. ..that the terminology for the strands of DNA with respect to transcription should therefore be formalized and the use of sense strand for DNA be avoided in future literature. One strand of DNA acts as the template for transcription and the other does not. When referring to DNA, the terms should be "transcribed strand"… and "non- transcribed strand"… The term antisense would be best reserved for RNA...Whether the members’ decision will be taken seriously and whether it will be come the existing standard remains to be seen. Methods and reagents. Is there any sense in antisense terminology? Hengen PN1. Trends Biochem Sci. 1996 Apr;21(4):153-4. https://www.ncbi.nlm.nih.gov/pubmed/8701474   Is this a moot point by now?

Molecular biologists describing DNA sequences or referring to one of the two strands of double- stranded DNA frequently use complementary pairs of terms, such as coding/ non- coding, sense/ nonsense or transcribing/ non- transcribing. Unfortunately none of these pairs is defined in a universally accepted way…Of the three pairs of terms mentioned, NC- IUB and JCBN believe coding/ non- coding to be preferable. Moreover, as the word 'coding' refers to the relationship between nucleic acids and proteins, rather than the mere transcription of DNA into RNA, it is logical to call the strand with the mRNA sequence the coding strand, as in the first example. When DNA sequences are described by giving the sequence of only one strand, this is usually the strand with the same sequence as the RNA (messenger, ribosomal, transfer, etc.) and should therefore be called the coding strand. [JCBN/ NC- IUB Newsletter, Joint Commission on Biological Nomenclature and Nomenclature Commission of IUB, 1989]  http://www.chem.qmw.ac.uk/iubmb/newsletter/misc/DNA.html  

Narrower terms: antisense DNA, antisense oligonucleotides, antisense RNA, Related terms: Biologics antisense therapy; RNAi; SNPs & other genetic variations missense mutation, nonsense mutation; Sequences DNA & beyond ribozymes

antisense DNA: DNA that is complementary to the sense strand. (The sense strand has the same sequence as the mRNA transcript. The antisense strand is the template for mRNA synthesis.) Synthetic antisense DNAs are used to hybridize to complementary sequences in target RNAs or DNAs to effect the functioning of specific genes for investigative or therapeutic purposes. MeSH, 1991

antisense oligonucleotides: Short fragments of DNA or RNA that are used to alter the function of target RNAs or DNAs to which they hybridize. MeSH, 1991 Related terms  antisense, antisense DNA, antisense RNA, morpholinos

aptamer: Oligonucleotide which displays specific binding to a protein or other target, often selected by an iterative cycle of affinity- based enrichment. A synthetic, specially- designed oligonucleotide with the ability to recognize and bind a protein ligand molecule or molecules with high affinity and specificity.    Narrower terms: photoaptamers,  Functional genomics  Protein technologies peptide aptamer;  Genomic technologies SELEX, spielgemers    

Aptamers are included in the IUPAC, Electrochemical nucleic acid based biosensors http://www.iupac.org/publications/pac/pdf/2010/pdf/8205x1161.pdf    

binding affinity: the strength of the binding interaction between a single biomolecule (e.g. protein or DNA) to its ligand/binding partner (e.g. drug or inhibitor). Binding affinity is typically measured and reported by the equilibrium dissociation constant (KD), which is used to evaluate and rank order strengths of bimolecular interactions. The smaller the KD value, the greater the binding affinity of the ligand for its target. The larger the KD value, the more weakly the target molecule and ligand are attracted to and bind to one another. Binding affinity is influenced by non-covalent intermolecular interactions such as hydrogen bonding, electrostatic interactions, hydrophobic and Van der Waals forces between the two molecules. In addition, binding affinity between a ligand and its target molecule may be affected by the presence of other molecules. There are many ways to measure binding affinity and dissociation constants, such as ELISAs, gel-shift assays, pull-down assays, equilibrium dialysis, analytical ultracentrifugation, SPR, and spectroscopic assays. Isothermal titration calorimetry (ITC) is a direct, label-free analytical technique which measures the binding affinity between any two molecules that interact with each other, such as a protein and a ligand.  Malvern Panalytical, Products Measurement Type https://www.malvernpanalytical.com/en/products/measurement-type/binding-affinity

binding, competitive: The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements. MeSH 1973 

binding site: A specific region (or atom) in a molecular entity that is capable of entering into a stabilizing interaction with another molecular entity. IUPAC Bioinorganic The reactive parts of a macromolecule that directly participate in its specific combination with another molecule. MeSH, 1968  Related terms: ligand; receptor mapping. Narrower term: binding sites, antibody 

binding sites, antibody: Local surface sites on antibodies which react with antigen determinant sites on antigens. They are formed from parts of the variable regions of the Fab fragment of the immunoglobulin. MeSH, 1973

chemical ligand studies: Use a more general set of compounds [than chemical genomics] (often from combinatorial libraries) to find new targets. Once the new targets are found, more specific assays are done. In other words, with the chemical ligands approach, one does blind screening of chemical libraries using cellular assays. When one gets an interesting biological effect, one uses the compound to find the target it modulates. [The precise definition of the following terms varies widely between drug discovery companies. The meanings given here are aligned with the use of the terms within the lead discovery function at GlaxoWellcome.  Martin J. Valler,  Darren Green  "Diversity screening versus focussed screening in drug discovery" Drug Discovery Today 5(7): July 2000 

deorphanize: Identification of new ligands for receptors.

drug leads: small molecule ligands  DS Wishart Identifying putative drug targets and potential drug leads: starting points for virtual screening and docking. Methods Mol Biol. 2008;443:333-51.

drug receptors: Proteins that bind specific drugs with high affinity and trigger intracellular changes influencing the behavior of cells. Drug receptors are generally thought to be receptors for some endogenous substance not otherwise specified.  MeSH, 1968  Broader term: receptors

efficacy: Describes the relative intensity with which agonists vary in the response they produce even when they occupy the same number of receptors and with the same affinity. Efficacy is not synonymous to intrinsic activity. The property that enables drugs to produce responses.  It is convenient to differentiate the properties of drugs into two groups, those which cause them to associate with the receptors (affinity) and those that produce stimulus (Efficacy). This term is often used to characterize the level of maximal responses induced by agonists. In fact, not all agonists of a receptor are capable of inducing identical levels of maximal responses. Maximal response depends on the efficiency of receptor coupling, i.e., from the cascade of events, which, from the binding of the drug to the receptor, leads to the observed biological effect. IUPAC Medicinal Chemistry

efficacy (in receptor pharmacology) Extent to which a compound activates a receptor to produce a response in an assay under saturating conditions. Note 1: Usually compared to results with the positive and negative assay controls. When the compound produces a maximal signal that is 100 % of that of the positive control, it is said to be a full agonist and has high efficacy. When the effect plateaus with increasing concentration to reach an intermediary level of activity, the compound is said to be a partial agonist with lower efficacy. Note 2: Due to the common overexpression of receptors in screening assays, it is not always possible to detect differences in efficacy among full agonists. A more accurate assessment of relative efficacy may require systems with lower receptor expression where it is often found that one agonist may show partial agonist character. See also partial agonist.  IUPAC Glossary of Biomolecular Screening

enzymes: Macromolecules, mostly of protein nature, that function as (bio) catalysts by increasing the reaction rates. In general, an enzyme catalyses only one reaction type (reaction specificity) and operates on only one type of substrate (substrate specificity). Substrate molecules are attacked at the same site (regiospecificity) and only one or preferentially one of the enantiomers or chiral substrates is attacked (stereospecificity). [IUPAC Compendium]

A substance (usually a protein) that speeds up, or catalyzes, a chemical reaction without being permanently altered or consumed. [NIGMS]

Biological molecules that possess catalytic activity. They may occur naturally or be synthetically created. Enzymes are usually proteins, however catalytic RNA (RNA, CATALYTIC) and catalytic DNA (DNA, CATALYTIC) molecules have also been identified. MeSH   Related terms: substrate, Metabolic engineering;  Pharmacogenomics enzyme kinetics Narrower term: immobilized enzymes

Enzyme nomenclature list, IUPAC, 1992 print edition & supplements http://www.chem.qmul.ac.uk/iubmb/enzyme/ See also Nomenclature Enzyme nomenclature for more detailed explanation.

enzymes and coenzymes: Biological catalysts and their cofactors. MeSH 2004

epitope: Any part of a molecule that acts as an antigenic determinant. A macromolecule can contain many different epitopes each capable of stimulating production of a different specific antibody. IUPAC Glossary Biomolecular Screening

Sites on an antigen that interact with specific antibodies. MeSH, 1996

Sites involved in noncovalent interactions. NS Greenspan and E Di Cera "Defining epitope: It’s not as easy as it seems" Nature Biotechnology 17:936- 937 Oct. 1999 Related terms antibody, antigen, hapten; Narrower terms: conformational epitopes Wikipedia http://en.wikipedia.org/wiki/Conformational_epitope  linear epitopes Wikipedia  http://en.wikipedia.org/wiki/Linear_epitope   Also known as discontinuous epitopes.  Mimotopes Wikipedia http://en.wikipedia.org/wiki/Mimotope  epitope mapping: Maps, genomic & genetic

hapten: A molecule (usually a small organic molecule) which can be bound to an antigenic determinant/ epitope. Usually they are too small to give a response of their own. They become antigenic if they are coupled to a suitable macromolecule, such as a protein. IUPAC Bioinorganic

Small antigenic determinants capable of eliciting an immune response only when coupled to a carrier. Haptens bind to antibodies but by themselves cannot elicit an antibody response. MeSH, 1965

homologue: Used to describe a compound belonging to a series of compounds differing from each other by a repeating unit, such as a methylene group, a peptide residue, etc. IUPAC Medicinal Chemistry

This is different from homolog/ homologue defined in the Functional genomics

hormone: A substance produced by endocrine glands, released in very low concentration into the bloodstream, and which exerts regulatory effects on specific organs or tissues distant from the site of secretion. [IUPAC Medicinal Chemistry] 

Chemical substances having a specific regulatory effect on the activity of a certain organ or organs. The term was originally applied to substances secreted by various endocrine glands and transported in the bloodstream to the target organs. It is sometimes extended to include those substances that are not produced by the endocrine glands but that have similar effects. MeSH Related term: receptor.

immobilized enzymes: Enzymes which are immobilized on or in a variety of water- soluble or water- insoluble matrices with little or no loss of their catalytic activity. Since they can be reused continuously, immobilized enzymes have found wide application in the industrial, medical and research fields. MeSH, 1977

immunogen: A substance that elicits a cellular immune response and/ or antibody production (cf. antigen). IUPAC Compendium

inhibitors: A substance that diminishes the rate of a chemical reaction. The process is called inhibition. Inhibitors are sometimes called negative catalysts but since the action of an inhibitor is fundamentally different from that of a catalyst this terminology is discouraged. In contrast to a catalyst, an inhibitor may be consumed in the course of a reaction. ... See also effector. [IUPAC Compendium]  Narrower term: promiscuous inhibitors

intrinsic activity:  The maximal stimulatory response induced by a compound in relation to that of a given reference compound (See also partial agonist) This term has evolved with common usage. It was introduced by Ariëns as a proportionality factor between tissue response and receptor occupancy. The numerical value of intrinsic activity (alpha) could range from unity (for full agonists, i.e., agonist inducing the tissue maximal response) to zero (for antagonists), the fractional values within this range denoting partial agonists. Ariëns' original definition equates the molecular nature of alpha to maximal response only when response is a linear function of receptor occupancy. This function has been verified. Thus, intrinsic activity, which is a drug and tissue parameter, cannot be used as a characteristic drug parameter for classification of drugs or drug receptors. For this purpose, a proportionality factor derived by null methods, namely, relative efficacy, should be used. Finally, "intrinsic activity" should not be used instead of "intrinsic efficacy". A "partial agonist" should be termed "agonist with intermediate intrinsic efficacy" in a given tissue.  IUPAC Medicinal Chemistry

ligand: In inorganic chemistry the ligands are the atoms or groups of atoms bound to the central atom (see also coordination). The root of the word is sometimes converted into the verb to ligate, meaning to coordinate as a ligand, and the derived participles, ligating and ligated…In biochemistry the term ligand has been used more widely: if it is possible or convenient to regard part of a polyatomic molecular entity as central, then the atoms or groups or molecules bound to that part may be called ligands. IUPAC Bioinorganic

Pharmacologists traditionally divide ligands into agonists, which stimulate receptors, and antagonists, which bind to receptors and block endogenous mediators. According to the conventional view, the agonist fits into the receptor, like a key fits a car's ignition, switching on the internal machinery. Antagonists fit the ignition, but block endogenous transmitters. But recent studies suggest that many receptors spontaneously activate internal machinery. In these cases, the receptor is more akin to an accelerator. Mark Greener, Driving Changes in Ligand Theory, The Scientist 18(15): 32, Aug. 2, 2004  

A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed) MeSH 1974 

Molecules (e.g., drugs) that bind to active sites on proteins. Particularly used of small molecules that bind to larger molecules. Narrower term: protein ligand; Related terms: antigen, binding site,  enzyme- substrate, hormone- receptor reaction, lock and key  

ligand binding:   The study of ligand binding is an essential step in identifying receptor binding sites. There are several methods for analysing ligand binding experiments. This laboratory offers the opportunity to compare the most widely used. Ligand binding models describe the interaction of one or more ligands with one or more binding sites. Binding sites can be described by their behaviour as being saturable or non-saturable. Saturable binding is also called specific binding and non-saturable binding is also called non-specific binding. Receptors have saturable binding sites and also express an effect. Models for ligand binding are based on the law of mass action. Models can describe the time course of binding (association and dissocation) but more commonly binding is described at equilibrium. The driving force for binding is the unbound ligand concentration but experimentally only total ligand concentrations can be varied. Measurements of bound ligand can be used to predict unbound ligand concentration (unbound=total-bound) but the measurement error in the bound concentration will influence the predicted unbound concentration. Ligand binding, Anita Sumpter, University of Auckland, Dept of Pharmacology and Clinical Phamacology http://holford.fmhs.auckland.ac.nz/teaching/medsci719/workshops/ligandbinding/
Related terms:  Drug discovery informatics drug design  Cheminformatics molecular design;  Targets binding site,

ligand design: The design of ligands using structural information about the target to which they should bind, often by attempting to maximize the energy of the interaction. IUPAC Computational

orphan receptors: Receptor for which no ligands have yet been identified.  Related terms: deorphan, deorphanize

peptide receptors: Cell surface receptors that bind peptide messengers with high affinity and regulate intracellular signals which influence the behavior of cells. MeSH, 1994

peptidomimetic: A compound containing non- peptidic structural elements that is capable of mimicking or antagonizing the biological action(s) of a natural parent peptide. A peptidomimetic does no longer have classical peptide characteristics such as enzymatically scissille peptidic bonds. (See also peptoids). IUPAC Medicinal Chemistry  Related terms: -Omes & -omics  peptidome, peptidomic

peptoid: A peptidomimetic that results from the oligomeric assembly of N-substituted glycines. IUPAC Medicinal Chemistry

pharmacophores: The ensemble of steric and electronic features that is necessary to ensure the optimal supramolecular interactions with a specific biological target structure and to trigger (or to block) its biological response. Does not represent a real molecule or a real association of functional groups, but a purely abstract concept that accounts for the common molecular interaction capacities of a group of compounds towards their target structure. Can be considered as the largest common denominator shared by a set of active molecules. This definition discards a misuse often found in the medicinal chemistry literature which consists of naming as pharmacophores simple chemical functionalities such as guanidines, sulfonamides or dihydroimidazoles (formerly imidazolines), or typical structural skeletons such as flavones, phenothiazines, prostaglandins or steroids. Pharmacophoric descriptors are used to define a pharmacophore, including H- bonding, hydrophobic and electrostatic interaction sites, defined by atoms, ring centers and virtual points. IUPAC Medicinal Chemistry The ensemble of steric and electronic factors which are necessary to insure supramolecular interactions with a specific biological target structure. IUPAC Combinatorial Chemistry

A  template of chemical properties for an active site of a protein - representing these properties’ spatial relationship to one another - that theoretically defines a ligand that would bind to that site.  pharmacophore generation: A procedure to extract the most important common structural  features relevant for a given biological activity from a series of molecules with a similar  mechanism of action. IUPAC Computational

paratope:  also called an antigen-binding site, is a part of an antibody which recognizes and binds to an antigen. It is a small region (of 5 to 10 amino acids[citation needed]) of the antibody's Fv region, part of the fragment antigen-binding (Fab region), and contains parts of the antibody's heavy and light chains.[1] Each arm of the Y shape of an antibody monomer is tipped with a paratope, which is a set of complementarity determining regions. The part of the antigen to which the paratope binds is called an epitope. This can be mimicked by a mimotope.  Wikipedia accessed 2018 Nov 6  http://en.wiktionary.org/wiki/paratope  Related term: binding sites

permeability:  Ability of a compound to diffuse across biological membranes. Related terms: bioavailability, biological availability

prodrug: Drugs that, once administered, must be chemically modified by metabolic processes in order to become pharmaceutically active.

Any compound that undergoes biotransformation before exhibiting its pharmacological effects. Prodrugs can thus be viewed as drugs containing specialized non- toxic protective groups used in a transient manner to alter or to eliminate undesirable properties in the parent molecule. IUPAC Medicinal Chemistry

promiscuous drugs: We contend that an ideal drug may be one whose efficacy is based not on the inhibition of a single target, but rather on the rebalancing of the several proteins or events, that contribute to the etiology, pathogeneses, and progression of diseases, i.e., in effect a promiscuous drug....  Corollaries to this argument are that the growing fervor for researching truly selective drugs may be imprudent when considering the totality of responses; and that the expensive screening techniques used to discover these, may be both medically and financially inefficient. Promiscuous drugs compared to selective drugs (promiscuity can be a virtue) Simon K Mencher and Long G Wang, BMC Clinical Pharmacology 2005, 5:3 doi:10.1186/1472-6904-5-3 http://www.biomedcentral.com/1472-6904/5/3/abstract  Related term: selectivity

promiscuous inhibitors: Nonspecific, seem to be hits in multiple high- throughput screening (HTS)  campaigns, but which turn out to be dead ends when attempts are made to optimise their activity, a key problem in the field of HTS.  Peter Kirkpatrick, Won't get fooled again, Nature Reviews Drug Discovery, 4(8): 630, August 2005  rotean ligands: The literature contains few examples of ligands that seem to be able to both promote and decrease activity at the same G-protein-coupled receptors. Such 'protean ligands' — so- called after the mythical character Proteus, who could adopt any shape he desired — have been proposed to work by acting as agonists with low efficacy. They thereby increase the activity of receptors that are basically silent under resting conditions, but decrease the activity of receptors that have high levels of ligand- independent, spontaneous (or constitutive) activity. In this model, protean behaviour therefore depends on having two populations of receptors with different levels of spontaneous activity. Adam Smith, Adrenoceptor pharmacology: How the ligand changed its spots Nature Reviews Drug Discovery 1, 569 Aug. 2002  https://www.nature.com/articles/nrd885

receptor: A protein or a protein complex in or on a cell that specifically recognizes and binds to a compound acting as a molecular messenger (neurotransmitter, hormone, lymphokine, lectin, drug, etc.). In a broader sense, the term receptor is often used as a synonym for any specific (as opposed to non- specific such as binding to plasma proteins) drug binding site, also including nucleic  acids such as DNA. IUPAC Computational  Narrower terms: amino acid receptors, cell surface receptors, drug receptors, receptor mapping In silico & Molecular modeling; Related terms:  ligand 

recognition site: 1. A nucleotide sequence to which a protein binds specifically. 2. An amino acid sequence in an antibody molecule to which the specific antigen binds specifically. IUPAC Biotech 
Related term: molecular recognition. Drug discovery & development

recombination: See genetic recombination SNPs & Genetic variations

selectivity: describes a drug's ability to affect a particular cell population in preference to others. As part of the current state of art in the search for new therapeutic agents, the property of selectivity is a mode of action thought to have a high degree of desirability....  Selectivity is generally a worthy property in a drug because a drug having high selectivity may have a dramatic effect when there is a single agent that can be targeted against the appropriate molecular-driver involved in the pathogenesis of a disease.  Promiscuous drugs compared to selective drugs (promiscuity can be a virtue) Simon K Mencher and Long G Wang, BMC Clinical Pharmacology 2005, 5:3 doi:10.1186/1472-6904-5-3 http://www.biomedcentral.com/1472-6904/5/3/abstract  

Selectivity is the recommended term in analytical chemistry to express the extent of interferences. To avoid confusion, the use of the term specificity is to be discouraged, as it is incorrect. A method is either specific or not. Few, if any, methods are specific. 2. Definition of Selectivity refers to the extent to which a method can determine particular analytes in mixtures or matrices without interferences from other components. Selectivity in analytica chemistry poster https://old.iupac.org/projects/posters01/vessman01.pdf

The extent to which a compound hits the intended drug target. Related term: promiscuous drugs

solubility: The analytical composition of a saturated solution, expressed in terms of the proportion of a designed solute in a designated solvent is the solubility of that solute. The solubility may be expressed as a concentration, molality, mole fraction, mole ratio, etc. IUPAC Compendium 1997

Ability of a compound to dissolve.  Related terms:  molality, molarity; Cheminformatics rule of five

specificity: The terms selectivity or specificity are in many cases used interchangeably. As specificity is considered as an absolute term, it cannot be graded. IUPAC has earlier stated that “specificity is the ultimate of selectivity”. The desire to avoid the term specificity has been expressed as “Sometimes the term specificity is used. This usage suggests that no component other than the analyte contributes to the result. Hardly any method is that specific (sic!) and, in general, the term should be avoided”.  Selectivity in analytica chemistry poster https://old.iupac.org/projects/posters01/vessman01.pdf

In the five disciplines that eventually contributed to the formation of molecular biology, ideas of specificity had widely different standing and character. In microbiology, the relevance of specificity in the present day sense awaited resolution of the long, piecemeal shift of opinions about what sort of creatures micro- organisms were....[Oswald Avery, Chargaff, Lwoff, Luria Delbruck, Jacques Monod, Alice Audureau]  Mendelian genetics itself had always been highly specific, of course, and from very early the genetic specificity - the map - was understood to form a strictly linear array  [Thomas Hunt Morgan, Boris Ephrussi, George Beadle, Edward Tatum]... In physical chemistry, specificity was not abstract and not linear, but concretely physical and three- dimensional [Pauling] ... Crystallography, in its way, was also permeated with specificity [Edward Tyson Reichert, Amos Peaslee Brown, Felix Haurowitz] ... Specificity in the present- day sense of unique molecular structures was never a surprise to the crystallographers ... The fifth discipline in the synthesis that formed molecular biology was biochemistry. Yet the standard view of the rise of molecular biology has somewhat taken for granted, for example, the radical sharpening of ideas of specificity represented by Fritz Lipmann's elucidation of the way energy is supplied to the steps of cellular reactions.  And it grievously undervalues the work of the two biochemists who proved decisive in changing the way people thought about specificity.  The man who released the present day understanding of molecular specificity in living processes was Frederick Sanger ... the most general and profound [result of his methods] was that proteins are entirely and uniquely specified.  Horace Freeman Judson Eighth Day if Creation, Cold Spring Harbor Laboratory Press, 1996 pp. 583- 585

100% specificity = 100% true negatives, 0% false negatives. See also Molecular Medicine (analytical and clinical sensitivity and specificity).

substrate: A chemical species, the reaction of which with some other chemical reagent is under observation (e. g. a compound that is transformed under the influence of a catalyst). The term should be used with care. Either the context or a specific statement should always make it clear which chemical species in a reaction is considered the substrate. IUPAC Compendium 

How does this definition compare with substrate Microarrays & protein arrays  Related term enzyme.

substrate specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts. MeSH, 1978

Bibliography
IUPAC  International Union of Pure and Applied Chemistry, Glossary of Terms used in Bioinorganic Chemistry, Recommendations, 1997. 450+ definitions. https://www.ncbi.nlm.nih.gov/books/NBK16710/
IUPAC  International Union of Pure and Applied Chemistry, Glossary of Terms used in Biomolecular Screening 2011 http://iupac.org/publications/pac/83/5/1129/
IUPAC International Union of Pure and Applied Chemistry, Compendium of Chemical Terminology: Recommendations, compiled by Alan D. McNaught and Andrew Wilkinson, Blackwell Science, 2005-2017. "Gold Book"  http://goldbook.iupac.org/
IUPAC Inernational Union of Pure and Applied Chemistry, Glossary of terms used in Computational Drug Design Part 1 https://www.degruyter.com/view/j/pac.1997.69.issue-5/pac199769051137/pac199769051137.xml
IUPAC International Union of Pure and Applied Chemistry, Glossary of Terms used in Computational Drug Design, Part II https://iupac.org/recommendation/glossary-of-terms-used-in-computational-drug-design-part-ii
IUPAC International Union of Pure and Applied Chemistry, Glossary of Medicinal Chemistry, 1998. 100+ terms. https://www.qmul.ac.uk/sbcs/iupac/medchem/
IUPAC Pharmaceutics 2009 https://www.iupac.org/publications/pac/81/5/0971/

How to look for other unfamiliar  terms

IUPAC definitions are reprinted with the permission of the International Union of Pure and Applied Chemistry.