Regulation of biodegradative threonine deaminase.

摘要: Publisher Summary The biodegradative threonine deaminases have been purified to homogeneity and crystallized from the extracts of Escherichia coli ( E. ) Clostridium tetranomorphum , respectively. It has demonstrated that are composed four identical subunits, each monomer containing one mole pyridoxal phosphate. deamination reaction mechanism studied using E . enzyme is compatible with derived pyridoxal-catalyzed α,β-elimination in non-enzymic model system, although direct evidence for participation phosphate lacking. Spectral circular dichroic changes enzyme-bound after addition substrate, L-threonine, were postulated represent formation a complex between dehydrated intermediate. Optical studies indicate optical occur prior β -elimination reaction. Kinetic analyses indicated exists as an inactive form under conditions these experiments. These phenomena could be interpreted indicating conversion this into active occurs L-threonine. observed during step appears rate-limiting overall employed.