The action of alpha-ketoglutarate dehydrogenase on 4-chloronitrosobenzene: evidence for species-dependent differences in active site properties.

The reaction of bovine (Bos taurus) and porcine (Sus scrufa) cardiac alpha-ketoglutarate dehydrogenase complex (alpha-KGD) with 4-chloronitrosobenzene (I) was shown to produce a hydroxamic acid (IV) and a product due to a Bamberger rearrangement as previously shown for Escherichia coli alpha-KGD. The conversion of I into an active site-bound electrophile was general among the three alpha-KGD enzymes tested, but quantitative differences in products and kinetics were shown. The reaction of I was specific for the resolved alpha-ketoglutarate decarboxylase subunit.