Enzymes: substances consisting largely or wholly of protein that are produced by a living organism and act like a catalyst to promote specific biochemical reactions. (Oxford) (Have) the ability to catalyze a chemical reaction. (Ridley, 138)

A "protein" that acts as a "catalyst," speeding the rate at which a biochemical reaction proceeds but not altering the direction or nature of the reaction. (HGPIA) Allows spontaneous "chemical reactions" to occur in ‘real time’ by lowering the “activation energy” for a specific chemical reaction. Each enzyme functions within specific environmental parameters such as "temperature," “pH” level, the amount of “substrate,” and the presence of “competitor molecules.” (Norman, 6/11/09) Enzymes can be “activated” or “inhibited.” (Norman, 6/17/09) Oversee the "synthesis" of "neurotransmitters" and their transport from the "presynaptic neuron" across the "synapse" to the "postsynaptic neuron." (Lewis, 151) Researchers led by Roger Kornberg solved the structure of "RNA polymerase II." This is the enzyme in mammalian cells that catalyzes the "transcription" of DNA into "messenger RNA," the molecule that in turn dictates the order of "amino acids" in proteins. For his work on the mechanisms of mammalian transcription, Kornberg received the Nobel Prize in Chemistry in 2006. (NIGMS)

Active Site: the location on an enzyme where the chemical reaction takes place. (Brooker, G1) The catalytic site of an enzyme, the part of an enzyme where the actual enzymatic function is performed. (NCIt) The region of an enzyme that interacts with its “substrate” to cause the enzymatic reaction. (MeSH)

Adenylate Cyclase: a protein membrane enzyme that helps carry out essential "nervous system" functions. (The Brain-Charles Stevens, 19) Membrane-associated enzymes of the ‘lyase’ class that are expressed in most human tissues. These enzymes catalyze the formation of “cyclic AMP” and ‘pyrophosphate’ from “ATP” and are regulated by a family of “receptors,” protein “kinases,” and “calcium.” Encoded by the ‘ADCY9’ gene and widely distributed. (NCIt)

Allosteric Site: a site where a molecule can “bind” and affect the function of the active site. The binding of a molecule to an allosteric site causes a “conformational change" in the enzyme that "inhibits" its catalytic function. (Brooker, G-2) A site on an enzyme which upon binding of a "modulator," causes the enzyme to undergo a conformational change that may alter its catalytic or binding properties. (MeSH)

Amylase: enzyme that helps break down “starch” into the “disaccharide” “maltose.” (Norman, 33) A group of enzymes that cleave “starch,” “glycogen,” and related (molecules). (MeSH)

ATP Synthase: a protein machine that runs on “hydrogen” and makes ATP from “ADP” and “phosphate.” (Batiza, 165) Enzyme that utilizes the energy stored in a (positively charged hydrogen "ion") “electrochemical gradient” for the “synthesis” of “ATP” via “chemiosmosis.” (Brooker, G-3) Making ATP is serious business for most, if not all, cells. The energy released when (its) outermost phosphate is broken off is used to power many reactions in the cell. (Batiza, 129)

Coenzymes: small molecules that are required for the catalytic function of enzymes. Many vitamins are coenzymes. (MeSH) Any nonprotein substance required by a protein for biological activity, such as (those) which are not consumed in the process and are found unchanged at the end of the reaction. (GHR) Organic molecules that participate in the chemical reaction but are left unchanged after the reaction is completed. (Brooker, 129) Often "vitamins," and can be "minerals." (Norman, 6/17/09) Also referred to as 'cofactors.'

Enzyme Activation: occurs in steps as follows: (1) “substrate” molecule binds to active site; (2) enzyme changes conformation to bind better to a substrate; and (3) binding causes a chemical reaction to occur. Enzymes can be activated or inhibited. (Norman, 6/17/09)

Enzyme Suppression: process that prevents an enzyme from doing its job. (Norton Lectures, 6/17/09)

Allosteric Inhibition: occurs in steps as follows: (1) a molecule other than a substrate binds to an allosteric site on the enzyme; (2) the enzyme changes conformation; (3) the active site changes conformation; (4) the substrate can no longer fit in active site; and (5) a chemical reaction can no longer occur in real time. Note -  pharmaceutical companies work on drugs that work with this process because it is easier to block the allosteric site than the active site. (Norton Lectures, 6/17/09) Also referred to as ‘indirect inhibition.’

 Competitive Inhibition: occurs in steps as follows: (1) a molecule other than a substrate binds to an enzyme active site; (2) a substrate molecule can no longer bind to the enzyme; and (3) a chemical reaction will not occur in real time. (Norton Lectures, 6/17/09)

Induced Fit: the conformation change an enzyme goes through to bind specifically to a substrate molecule. (Norman, 6/17/09) A model of enzyme-substrate interaction in which the substrate induces a conformational change in the active site of an enzyme on binding which enables the substrate to fit into the active site. (Lawrence)

Lipase: the major fat-digesting enzyme from the "pancreas." (Brooker, G-21) Produced by glands on the tongue and by the pancreas and initiates the digestion of dietary fats. (MeSH) Secreted in the digestive tract. Catalyzes the breakdown of “fats” into individual “fatty acids” that can be absorbed into the bloodstream. (NCIt)

Nuclease: any of various enzymes that promote “hydrolysis” of “nucleic acids.” (GHR) Enzyme that breaks down “RNA.” (Brooker, 130) It clips out certain DNA segments. (Norman, 7/2/09)

Endonuclease: a protein that cuts DNA. (GeneReviews) A nuclease that cleaves nucleic acids at internal sites. (Lawrence)

Polymerase: enzyme that builds a "polymer." (Lewis, 175) Enzyme that catalyzes the synthesis of nucleic acids on preexisting nucleic acid templates, assembling RNA from “nucleotides” or DNA from ‘deoxyribonucleotides.’ (HGPIA)

Protease: enzymes acting on peptide bonds. (NCIt) Cuts proteins into smaller "polypeptides." (Brooker, G-30) Any of numerous enzymes that (use hydrolysis on) proteins and are classified according to the most prominent “functional group” at the active site. (GHR)

Restriction Enzymes: restriction enzyme cutting site. (GHR) A sequence of DNA that is recognized by an endonuclease as a site at which the DNA is to be cut. (GeneReviews) A specific nucleotide sequence of DNA at which a particular restriction enzyme cuts the DNA. Some sites occur frequently in DNA (e.g., every several hundred base pairs); others, much less frequently (e.g., every 10,000 base pairs). (HGPIA) Also referred to as ‘restriction enzyme cutting site.’

Restriction Site: restriction enzyme cutting site. (GHR) A sequence of DNA that is recognized by an endonuclease as a site at which the DNA is to be cut. (GeneReviews) A specific nucleotide sequence of DNA at which a particular restriction enzyme cuts the DNA. Some sites occur frequently in DNA (e.g., every several hundred base pairs); others, much less frequently (e.g., every 10,000 base pairs). (HGPIA) Also referred to as ‘restriction enzyme cutting site.’

Reverse Transcriptase: "viral" enzyme that helps RNA copy its RNA into DNA so it can insert into a human chromosome. (Lewis, 327) Enzyme used by "retroviruses" to form a "complementary DNA" sequence (cDNA) from their RNA. The resulting DNA is then inserted into the chromosome of the "host cell." (HGPIA) Contributed to improving the methods used to read the "genetic code." Routinely used to create "cDNA" clones from mRNA, which allows for "DNA sequencing" of expressed genes. (Venter, 67)

Secretase: mutated secretase cuts beta amyloid protein into sticky fragments that accumulate to toxic levels in Alzheimer’s. (Lewis, 216) Three secretase subtypes referred to as alpha, beta, and gamma have been identified based upon the region of amyloid protein precursor they cleave. (MeSH)