Trypsin-treated Neurospora tryptophan synthetase

摘要: Tryptic digests of highly purified native Neurospora crassa TSase‡ have been examined for retention enzymic properties, number bonds hydrolyzed, and fractionation properties surviving activities. The kinetics tryptic inactiva-tion three reactions catalyzed by TSase were examined. Both reaction 1, the conversion indole-3-glycerolphosphate plus L -serine to -tryptophan D -glyceraldehyde-3-phosphate, also 2, indole -tryptophan, decline exponentially over approximately a 100-fold range. Although 3 has regarded as reversible splitting indole-3-glycerol phosphate rates inactivation forward (F) reverse (R) differ markedly from each other. Furthermore, both 3F 3R are more stable treatment than 1 2. Further analysis confirms that activities assayed associated with tryptophan synthetase, but indicates formulation this is inadequate. A comparison 2 loss -serine-pyridoxal stimulation suggests hydrolysis single, critical peptide bond alters ability enzyme bind two compounds. Titrimetric determinations show alterations be less 5% total lysine arginine bonds. Sephadex electrophoresis on acrylamide gel indicate molecule nearly size enzyme, different electrophoretic mobility.