CHE 4341 Lecture Notes - Lecture 12: Divergent Evolution, Zymogen, Nucleophile
Document Summary
Some enzymes require an additional chemical component (cofactor) to function. Cofactor: non-protein component metal ions small organic molecules (coenzymes) can be. Coenzymes often come from vitamins amounts in the diet. Apoenzyme (=apoprotein) : protein component of the enzyme. When the cofactor is tightly bound, it"s called a prosthetic group. Note: 1+ can apply for an enzyme: proximity effects. Positioning molecule(s) close together for a rxn. Molecules close to each other == rate increases x1000. Orienting them even closer == rate increases x10^5. Freezing out the rotational & translation motions of the substrates & reacting groups increases rate up to 10^7. The significant entropic cost associated w/ loss of translational & rotational freedom is paid for by the very favorable h of enzyme & substrate binding: gabc stabilize an unstable ts, therefore decreasing ea. Donating/accepting a h+ by providing a weak acid/base group to: covalent catalysis (nucleophilic catalysis) Enzyme"s active site provides a nucleophile that forms a covalent.
