title: Accuracy-rate tradeoffs: how do enzymes meet demands of selectivity and catalytic efficiency?
abstract: I discuss some physico-chemical and evolutionary aspects of enzyme accuracy (selectivity, specificity) and speed (turnover rate, processivity). Accuracy can be a beneficial side-product of active-sites being refined to proficiently convert a given substrate into one product. However, exclusion of undesirable, non-cognate substrates is also an explicitly evolved trait that may come with a cost. I define two schematic mechanisms. Ground-state discrimination applies to enzymes where selectivity is achieved primarily at the level of substrate binding. Exemplified by DNA methyltransferases and the ribosome, ground-state discrimination imposes strong accuracy-rate tradeoffs. Alternatively, transition-state discrimination, applies to relatively small substrates where substrate binding and chemistry are efficiently coupled, and evokes weaker tradeoffs. Overall, the mechanistic, structural and evolutionary basis of enzymatic accuracy-rate tradeoffs merits deeper understanding.
authors: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel. Electronic address: dan.tawfik@weizmann.ac.il.
authors: Dan S
authors: DS
authors: Tawfik
mesh_terms: D055162:Biocatalysis; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000737:chemistry / Q000378:metabolism; D004798:Enzymes / Q000378:metabolism*; D019143:Evolution, Molecular; D012270:Ribosomes / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D004798:Enzymes; D004248:DNA (Cytosine-5-)-Methyltransferases