Partial Characterization of Intracellular Protease Activity Which Participates in the Inactivation of Carbamyl Phosphate Synthase in Phycomyces Blakesleeanus

Abstract

We have partially characterized an intracellular fraction from Phycomyces blakesleeanus which shows proteolytic activity. The apparent thermal inactivation constant (Kd) was 0.12min-¹ at 50°C. This proteolytic fraction was split into two active fractions by ultrafiltration using a membrane with an exclusion size of 30,000. Both fractions were inhibited by phenyl methyl sulphonyl fluoride. The K, value for the fraction with molecular weight >30,000 was 0.075 mM. The fraction with molecular weight < 30,000 inactivated the Phycomyces CPS.

Key Words: :

• Intracellular protease activity
• carbamyl phosphate synthase
• CPS
• Phycomyces