Lysine 2,3-aminomutase. Purification and properties of a pyridoxal phosphate and S-adenosylmethionine-activated enzyme.

摘要: Abstract The enzyme lysine 2,3-aminomutase from Clostridium SB4 which catalyzes the conversion of l-lysine to l-β-lysine has been studied. A satisfactory radiochemical assay developed. Although is inactivated rapidly by exposure oxygen, it can be fully activated anaerobic incubation with a sulfhydryl compound for 1 hour at 37°. Optimal activation occurs when 0.9 mm ferrous ion present; evidence presented that enzyme-bound required activity. moderately stable and purified 53-fold in 10% yield specific activity 6.4 units per mg. best preparations appear least 95% homogeneous on basis disc gel electrophoresis filtration. molecular weight 285,000 estimated two different procedures. sedimentation coefficient 10.0 S. addition S-adenosylmethionine stimulated activity; near maximal was achieved 3.7 moles mole were added assay. apparent Km 2.8 x 10-8 m. S-Adenosylhomocysteine inhibits competitively S-adenosylmethionine. stereospecific l-lysine; 6.6 mm. S-Aminoethylcysteine competitive inhibitor (Ki = 56 µm). aminomutase reaction reversible; equilibrium constant (K (l-β-lysine)/(l-lysine)) 37° 6.7. absorption spectrum peak 420 mµ similar some pyridoxal phosphate enzymes. absorbance are decreased treatment cysteine, hydroxylamine, or isonicotinic acid hydrazide. Analytical data show contains 1.7 protein-bound vitamin B6 mole. Experiments D2O T2O little no exchange between solvent hydrogen β-lysine during reaction.