Enzymes Flashcards
(9 cards)
What is bond strain?
Occurs when affinity of E to TS is greater than to S, structural rearrangements occur, straining S bonds into position closer to conformation of TS .
Lowers energy difference between TS and S.
How does catalysis by proximity work?
ES interactions align chemical gps
Reduced entropy of reactants –> reduction in LOSS of entropy when two reactants form a product.
What is the function of lyases and ligases?
catalyse reactions in which a gp eliminated from a substrate to form a double bond.
Joining together of two molecules at expense of ATP pr another free energy source.
Give an example of an irreversible enzyme.
di-isopropyl phosphofluoridate binds chymotrypsin and chemically modifies serine in active site.
Give examples of competitive and uncompetitive enzymes.
succinate dehydrogenase is inhibited by malonate
enolase is inhibited by fluoride ions.
What is the effect of the KNF model on monomeric enzymes?
activators change structure or dynamics.
What kind of kinetic model is exhibited by ATCasee?
Concerted.
But sequential is the only one that can explain the negative cooperativity.
What is an allosteric site?
An enzyme site, different from active site, non competitively binds molecule other than S and may influence enzyme activity,
Why would you use a line weaver Burke plot?
Straight line so more accurate estimate of Km and Vmax than MM
