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Ch. 23 Enzymes
| Term | Definition |
|---|---|
| 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
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