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Ch. 23 Enzymes

TermDefinition
Stereoselective ex. enzymes that only catalyze the reactions of only L-amino acids
Apoenzyme Protein part of an enzyme
Cofactor a nonprotein portion of an enzyme that is necessary for catalytic function ex) metallic ions like Zn2+ and Mg2+
Coenzyme nonprotein organic molecule, frequently a B vitamin, that acts as a cofactor
Substrate the compound or compounds whose reaction an enzyme catalyzes
Active Site the specific portion of the enzyme to which a substrate binds during reaction
Inhibition Any process that makes an active enzyme less active or inactive
Competitive Inhibition a substance that binds to the active site of an enzyme thereby preventing binding of a substrate
Noncompetitive inhibitor any substance that binds to a portion of the enzyme other than the active site and thereby inhibits the activity of the enzyme
Enzyme concentration Linear
Substrate concentration increases and then levels off
Irreversible inhibition of enzymes if inhibitor covalently and permanently binds at or near active site of enzyme
allosterism enzyme regulation based on an event occuring at a place other than the active site but that creates a change in the active site
Regulator A substance that binds to an allosteric enzyme
Proenzyme (zymogen) An inactive form of an enzyme that must have part of its polypeptide chain hydrolyzed and removed before it becomes active ex) trypsin, digestive enzyme
Protein modification the process of affecting enzyme activity by covalently modifying it
Isoenzyme enzyme that occurs in multiple forms; each catalyzes the same reaction, but different forms are found in different tissues
Isoenzyme: lactate dehydrogenase (LDH) catalyzes the oxidation of lactate to pyruvate
H4 heart muscle, if found in serum could point to heart attack and is allosterically inhibited by high levels of pyruvate
M4 live and skeletal muscles
Transition-state analog a molecule whose shape mimics the transition state of a substrate *used experimentally to verify the nature of an active site *Used clinically to inhibit enzyme activity *potentially used to design artificial enzyme
abzyme an antibody that has catalytic activity because it was created using a transition state analog as an immunogen
The Central Dogma info contained in DNA molecules is expressed in the structure of proteins *Gene expression is the turning on or activation of a gene
Transcription the process of information encoded in a DNA molecule is copied into an mRNA molecule
Transcription Continued *takes place in nucleus *starts when the DNA double helix begins to unwind near the gene to be transcribed*only one strand of DNA is transcribed*polymerases catalyze transcription
Recombinant DNA 2 or more DNA segments from different species made into one molecule *this technique is used to turn a bacterium into an insulin factory
What is true of isozymes there are different forms of the same enzyme found in different tissues
Which of the following is commonly associated with protein modification? phosphorylation and dephosphorylation
the names of enzymes are often derived from? the reaction they catalyze and the compound on which they act
which of the following are monitored to diagnose the severity of a heart attack? AST, CPK, LDH
which type of inhibition is it possible to restore the maximum rate of enzyme activity by adding additional substrate? competitive inhibition
What name is given to the intermediate in an enzyme-catalyzed reaction? enzyme-substrate complete
What is the general name used when the product of a reaction sequence inhibits an earlier step in that sequence? feedback control
What is the reason that trypsin is synthesized as trypsinogen? trypsin would attack the body's natural proteins
What name is given any (organic or innorganic)nonprotein protion of an enzyme? Cofactor
what will cause the rate of enzyme activity to increase linearly? increasing the enzyme concentration
what is used to diagnose infectious hepatitis? ALT
What term is used to describe a species which affects the functioning of an allosteric enzyme? Regulator
what is the majority of enzymes? globular
What type of molecules sometimes function as enzymes? RNA
What name is given to the molecule on which the enzyme works? Substrate
Why is succinylcholine used as a muscle relaxant? it is slowly hydrolyzed by acetylcholinestrase
what disease is diagnosed by monitoring acid phosphatase activity? prostate cancer
What type of inhibition does the inhibitor bind to the protein at a site other than the active site? noncompetitive inhibition
What is true of all allosteric enzymes? binding at one site affects the protein function at a second site
What will cause the rate of enzyme activity to first increase and then level off? increasing the substrate concentration
What type of inhibition does the inhibitor bind to the active site? competitive inhibition
What name is given to the organic cofactor of an enzyme? coenzyme
What disease is diagnosed by monitoring amylase activity? pancreatic cancer
What is associated with noncompetitive inhibition? allosterism
Created by: aoyler