BCH 361 Lecture Notes - Lecture 1: Isopropyl Alcohol, Stereospecificity, Acetaldehyde
Document Summary
In general, a substrate-binding site consists of an indentation or cleft on the surface of an enzyme molecule that is complementary in shape to the substrate (geometric complementarity). Moreover, the amino acid residues that form the binding site are arranged to specifically attract the substrate (electronic complementarity, fig. Molecules that differ in shape or functional group distribution from the substrate cannot productively bind to the enzyme. The complementarity between enzymes and their substrates is the basis of the. Lock-and-key model of enzyme function fi rst proposed by emil fischer in 1894. Enzymes are stereospecific - enzymes are highly specific both in binding chiral substrates and in catalyzing their reactions. This stereospecificity arises because enzymes, by virtue of their inherent chirality (proteins consist of only l-amino acids), form asymmetric active sites. A few enzymes are absolutely specific for only one compound. Most enzymes, however, catalyze the reactions of a small range of related compounds although with diff erent efficiencies.
