Observation of covalent intermediates in an enzyme mechanism at atomic resolution.
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Heine A, DeSantis G, Luz JG, Mitchell M, Wong CH, Wilson IA
Observation of covalent intermediates in an enzyme mechanism at atomic resolution.
Science. 2001 Oct 12;294(5541):369-74.
- PubMed ID
- 11598300 [ View in PubMed]
- Abstract
In classical enzymology, intermediates and transition states in a catalytic mechanism are usually inferred from a series of biochemical experiments. Here, we derive an enzyme mechanism from true atomic-resolution x-ray structures of reaction intermediates. Two ultra-high resolution structures of wild-type and mutant d-2-deoxyribose-5-phosphate (DRP) aldolase complexes with DRP at 1.05 and 1.10 angstroms unambiguously identify the postulated covalent carbinolamine and Schiff base intermediates in the aldolase mechanism. In combination with site-directed mutagenesis and (1)H nuclear magnetic resonance, we can now propose how the heretofore elusive C-2 proton abstraction step and the overall stereochemical course are accomplished. A proton relay system appears to activate a conserved active-site water that functions as the critical mediator for proton transfer.