Steele Proteins 4 Flashcards
T or F. Many amino acid side chains that function in catalysis have atypicial pKa values as a result of the immediate environment in the protein.
True.
T or F. Catalytic resides of enzymes are usually nucleophiles.
True.
T or F. Catalytic subunits can be on different domains and different segments of the primary sequence.
True.
What are the main players of LDH (pyruvate to lactate)?
His 195 is the proton donor
Asp 168 stabilizes/orients His 195
Arg 171 is the binding residue
Arg 109 pulls/polarizes substrate to facilitate H donation by NADH
What are catalytic triads and where are they found?
3 side chains that interact to transfer charge through space. Found on many hydrolytic enzymes. (serine protease cleaving peptide bonds).
T or F. Most enzymes can act on analogs.
True.
The requirement of specific multipoint attachment of a substrate to enzyme is a term called _______.
Stereospecificity.
What are the differences between the substrate pockets of chymotrypsin, trypsin and elastase?
Chymo has broad, open pocket. Trypsin has negative charge in pocket. Elastase is hydrophobic and crowded.
Compared to an uninhibited enzymatic reaction, competitive inhibition’s Vmax is __________.
Unchanged.
T or F. In noncompetitive inhibition, Vmax is the same as in an uninhibited reaction.
False. Vmax is lower, regardless of substrate concentration.
In competitive inhibition, Vmax is _______ and Km is _______. In noncompetitive inhibition, Vmax is _______ and Km is ______.
unchanged, changed.
changed, unchanged.
Irreversible enzyme inhibition is usually a product of _________ modification of the enzyme.
Covalent modification.
T or F. Binding to an allosteric site can increase activity, decrease activity or even change the specificity of an enzyme.
True.
What are some of the trace elements that are common metal cofactors?
Zinc, magnesium, calcium
What are the common 3 components of collagen? (amino acids)
glycine (small), hyp (hydroxy proline). hyl (hydroxylysine).
