Biochem [Enzymes 7]

competitive inhibition

inhibitor binds to the active site

Km increases

Vmax unchanged

noncompetitve inhibition

binds to the allosteric site

Km unchanged

Vmax decreases

uncompetitive inhibition

inhibitors binds to the enzyme substrate complex

Km decreases

Vmax decreases

Km

enzymes affinity for substrate

lower Km, means higher affinity

which is half Vmax

Vmax

speed of the enzyme

maximum reaction rate

catalytic efficiency

[kcat/km]

turnover rate

how well an enzyme converts its substrate molecules into products

higher value, means greater catalytic efficiency

zymogen

inactive precursor of an enzyme

coenzyme

all coenzymes are cofactors but not all cofactors are coenzymes

are organic molecules that binds to the active site of certain enzymes to increase catalytic efficiency

eg NAD+, FAD, coenzyme A

cofactors

bind to allosteric sites

eg Mg2+, Zn2+

lyase

breaks covalent bonds without water, oxidation, reduction

eg decarboxylase

A —> B+C

ligase

joins molecules

eg DNA ligase

A+B—> AB

isomerase

rearranges bonds in a molecule

reactant forms one of its isomers

eg phosphoglucose isomerase, mutase

A—> B

hydrolase

uses water to cleave molecules

breaks covalent bonds with water

eg hydrolase, phosphatase, protease

A + H2O —> B + C

transferase

transfers a functional group from one molecule to another

eg kinase, phosphorylase, peptidyl transferase

AX + B —> A + BX

oxidoreductase

transfers electrons from one molecule to another, alters oxidation state of reactants

eg lactate dehydrogenase

A + B: —> A: + B