Biochemistry Flashcards
Trypsin
cleaves at carboxyl end of arginine and lysine.
Chymotrypsin
cleaves at carboxyl end of phenylalanine, tryptophan, and tyrosine.
Zymogen
inactivated form of enzyme.
Oxidoreductase
catalyze oxidation-reduction reactions.
Ex: dehydrogenase, reducatase, oxidase
Transferases
catalyze the movement of a functional group from one molecule to another. Ex: kinases, aminotransferases
Hydrolases
catalyze the breaking of a compound into two molecules using the addition of water.
Lyases
catalyze the cleavage of a single molecule into two products.
Isomerases
catalyze the rearrangement of bonds within a molecule.
Ligases
catalyze addition or synthesis reactions.
Cofactors
small inorganic molecules or metal ions
Coenzymes
small organic groups most of which are vitamin or vitamin derivatives.
If Hill’s coefficient is greater than 1
positive cooperative binding is occurring, after one ligand is bound the affinity of the enzyme for further ligand increases.
If Hill’s coefficient is less than 1
negative cooperative binding is occurring, after one ligand is bound the affinity of the enzyme for further ligand decreases.
If Hill’s coefficient is equal to 1
the enzyme does not experience cooperative binding.
What are the four types of reversible inhibition?
competitive, non-competitive, mixed, and uncompetitive.
Competitive Inhibition
involves occupancy of the active site, the Km increases, and the Vmax remains unchanged.
Non-competitive inhibition
bind to an allosteric site instead of the active site, which induces a change in enzyme conformation. Km is unchanged, Vmax decreases.
Mixed Inhibition
results when an enzyme can bind to either the enzyme or the enzyme-substrate complex but has different affinity for each. Km increases or decreases, Vmax decreases.
Uncompetitive Inhibition
bind only to enzyme-substrate complex and essentially lock the substrate in the enzyme preventing its release. Km decreases, Vmax decreases.
Feedback inhibition
refers to the product of an enzymatic pathway turning off enzymes further back in that same pathway.
Irreversible inhibition
prolonged or permanent inactivation of an enzyme.
What are examples of transient modifications to enzymes?
allosteric activation or inhibition
What are examples of covalent modifications to enzymes?
phosphorylation and glycosylation
What does a sigmoidal curve indicate in terms of cooperativity?
Positive Cooperativity and a Hill Coefficient Greater than 1.
