FIG 4.
Formation and spontaneous decay of the aminoacrylate intermediate at the CysK2 active site monitored by stopped-flow spectrophotometry. (A) Aminoacrylate formation and decay were measured with 100 μM enzyme and 100 μM OPS in a stopped-flow spectrophotometer at 475 nm. The fast formation of the enzyme-aminoacrylate intermediate (inset on left) is followed by a spontaneous decomposition (inset on right) with a half-life of 8.49 s. (B) In the presence of 2 mM Na2S, the consumption of the reaction intermediate is approximately 14 times faster than the spontaneous decomposition.