Term
| some strategies enzymes use to facilitate the formation of transition states |
|
Definition
1: covalent catalysis
2: general acid-base catalysis
3: metal ion catalysis
4: catalysis by approximation and orientation |
|
|
Term
|
Definition
| active site contains reactive group, usually a powerful nucleophile that becomes temporarily covalently modified in the course of catalysis |
|
|
Term
| general acid-base catalysis |
|
Definition
| molecule other than water plays role of proton donor or acceptor |
|
|
Term
|
Definition
metal acts as an electrophilic catalyst either by stabilizing a negative charge on a rxn intermediate, generating a nucleophile by increasing the acidity of nearby molecules, or increasing the binding energy of the enzyme-substrate interaction by binding to substrates
basically, metal ion draws electrons away from substrate |
|
|
Term
| catalysis by approximation and orientation |
|
Definition
| enhancing rxn rate by bringing 2 substrates into proximity and in the proper orientation on a single binding surface on the enzyme |
|
|
Term
| enzyme activity can be modulated by... |
|
Definition
-temp
-pH
-inhibitory molecules |
|
|
Term
| why increased heat increases enzyme activity |
|
Definition
| because it increases the Brownian motion, and therefore the chance of collision, making activity more likely |
|
|
Term
| enzyme activity increases with temp until... |
|
Definition
| the enzyme becomes denatured |
|
|
Term
| the pH dependence of enzymes is due to... |
|
Definition
|
|
Term
| how enzyme inhibitors can be useful |
|
Definition
| specific inhibitors can be used to identify residues critical for catalysis |
|
|
Term
| an especially potent type of inhibitor |
|
Definition
|
|
Term
|
Definition
| characterized by rapid dissociation of the enzyme-inhibitor complex |
|
|
Term
| 3 common types of reversible inhibition |
|
Definition
-competitive inhibition
-uncompetitive inhibition
-noncompetitive inhibition |
|
|
Term
|
Definition
| inhibitor resembles the substrate and binds to the active site |
|
|
Term
| how competitive inhibition can be alleviated |
|
Definition
| by increasing the concentration of substrate |
|
|
Term
|
Definition
| inhibitor binds to enzyme-substrate complex; binding of enzyme to substrate creates active site for uncompetitive inhibitor |
|
|
Term
| can increased concentration of substrate overcome uncompetive inhibition? |
|
Definition
|
|
Term
| noncompetitive inhibition |
|
Definition
| noncompetitive inhibitor binds to alternate site to make enzyme less functional |
|
|
Term
| can noncompetitive inhibition be overcome by increasing the concentration of substrate? |
|
Definition
|
|
Term
| depiction of competitive inhibition |
|
Definition
|
|
Term
| depiction of uncompetitive inhibition |
|
Definition
|
|
Term
| depiction of noncompetitive inhibition |
|
Definition
|
|
Term
| the hallmark of competitive inhibition |
|
Definition
| it can be overcome by sufficient concentrations of substrate |
|
|
Term
| kinetics of a competitive inhibitor |
|
Definition
| raises the KM (this new apparent value is called (KMapp)
does not affect the Vmax |
|
|
Term
| what uncompetitive inhibition of an enzyme does to that enzyme's rxn |
|
Definition
| makes the ES complex not proceed to form any product |
|
|
Term
| kinetics of an uncompetitive inhibitor |
|
Definition
| lower Vmax, now called VMapp
lower KM, now called KMapp |
|
|
Term
| kinetics of noncompetitive inhibition |
|
Definition
| lower Vmax, now called VMapp
KM unchanged
it's as if there's less enzyme |
|
|
Term
| something irreversible inhibitors can be used for |
|
Definition
|
|
Term
|
Definition
| dissociates very slowly from target enzyme due to tight bonding, either covalent or noncovalent |
|
|
Term
| irreversible inhibitors that covalently bind to enzymes are used for... |
|
Definition
elucidating mechanisms of enzymes
if inhibitor decreases function, this suggests that modified group is needed for proper function |
|
|
Term
| the first step in determining the chemical mechanism of an enzyme |
|
Definition
| to determine which functional groups are required for enzyme activity |
|
|
Term
| 4 categories of irreversible inhibitors |
|
Definition
1: group-specific reagents
2: affinity labels (substrate analogs)
3: suicide inhibitors
4: transition-state analogs |
|
|
Term
|
Definition
| type of irreversible inhibitor that modifies specific R groups of amino acids |
|
|
Term
| affinity labels (substrate analogs) |
|
Definition
type of irreversible inhibitor covalently modifies active site residues and is structurally similar to an enzyme's substrate
thus more specific for active site than group-specific reagents |
|
|
Term
| suicide inhibitors aka mechanism-based inhibitors |
|
Definition
type of irreversible inhibitor that is a chemically modified substrate
binds to enzyme as substrate to produce reactive intermediate that inactivates enzyme by covalent modification |
|
|
Term
| type of irreversible inhibitor that provides researchers the most specific means of modifying an enzyme's active site |
|
Definition
| suicide inhibitors aka mechanism-based inhibitors |
|
|
Term
|
Definition
| type of irreversible inhibitor that closely resembles the transition state and potently inhibits the enzyme |
|
|
Term
| important piece of info supporting the role of the formation of transition states in enzyme catalysis |
|
Definition
| the inhibitory power of transition-state analogs |
|
|
