Butyryl coenzyme A dehydrogenase: studies on the specificity of the formation of acyl coenzyme A complexes with long-wavelength absorption.

Further studies of butyryl CoA dehydrogenase show that the enzyme forms tight complexes with long-wavelength absorption bands upon addition of a,^-unsaturated alicyclic carboxyl ic acyl CoA compounds. A s in the straight chain series, the size of the acyl moiety is critical. The thiol portion by contrast determines neither whether a long-wavelength band is formed nor the wavelength of maximum absorption if such a band is present. It does however markedly affect the dissociation constant. Unusual features of the acid stability of the acyl C o A found on the native green form of the enzyme are also reported.