Purification and partial characterization of an extracellular serine-proteinase of Streptomyces cyaneus isolated from Brazilian cerrado soil

Streptomyces cyaneus, a micro-organism isolated from Brazilian cerrado soil , produces an extracellular proteinase (SCP), which was purified 22-fold to homogeneity from culture supernatant fluid, using a single aprotinin-agaro se affinity chromatography step. It is produced at a level corresponding to approximately 15% of total protein, but its physiological function has yet to be determined. The molecular mass of this S. cyaneus proteinase was est imated to be 120 kDa by gel filtration high performance liquid chromatograp hy, and it migrates by SDS-PAGE as a single band of 30 kDa. It was optimall y active at 25 degrees C and pH 9.0, and was fully inhibited by the serine- proteinase inhibitors PMSF and TPCK. A K-m value of 1.86 x 10(-5) mmol l(-1 ), and V-max of 2.0 x 10(-2) mmol l(-1) (Abs(247 nm) mu g(-1) min(-1)), wer e calculated for alpha-N-p-tosyl-l-arginine-methyl ester (TAME) as substrat e.