Suicide inhibition of alpha-oxamine synthases

ion from the trifluoroalanine-PLP imine is the first step in the process. An additional uncertainty was the nature of the enzyme nucleophilic group involved. In alanine racemases and cystathionine b-lyase the nucleophile is the active site lysine which both anchors the PLP and acts as the base for a-H abstraction. However in the analogous adducts formed between 2,2-difluoromethylornithine and ornithine and diaminopimelate decarboxylases, cysteine thiol groups act as the nucleophiles in the Michael addition. To resolve these uncertainties we attempted to prepare the enzyme trifluoroalanine adduct in a crystalline form. However we were unable to crystallise the preformed adduct and so single crystals of holo-AONS were soaked in a solution containing Ltrifluoroalanine (10 mM) and PLP (10 mM) in crystallisation 1210 | Org. Biomol. Chem., 2006, 4, 1209–1212 This journal is © The Royal Society of Chemistry 2006 Pu bl is he d on 0 1 M ar ch 2 00 6. D ow nl oa de d by U ni ve rs ity o f E di nb ur gh o n 31 /0 5/ 20 13 0 9: 41 :3 7. View Article Online