Poonam Mander

Purification, biochemical properties and antithrombotic effect of a novel Streptomyces enzyme on carrageenan-induced mice tail thrombosis model

INTRODUCTION The prevalence of cardiovascular diseases, one of the major causes of worldwide mortality, is being increasingly reported. Safer, more effective, and less expensive thrombolytic drugs can possibly overcome the underlying problems associate with current thrombolytic drugs. METHODS A thrombolytic enzyme was purified and characterized from a Streptomyces strain. Carrageenan induced tail-thrombosis mice model was used to evaluate in vivo antithrombotic effect of the enzyme. RESULTS First 15N-terminal amino acids of the purified enzyme were IAGGQAIYAGGGRRS, which are significantly different from the reported fibrinolytic enzymes. The enzyme exhibited 14.3±2.3-fold stronger thrombolytic activity than that of plasmin. In carrageenan induced tail-thrombosis model, the enzyme caused reduction in frequency of thrombus. Tail-thrombus of the enzyme treated group was significantly shorter than the physiological saline treated group and the thrombus decrement was correlated with the enzyme dose. CONCLUSIONS The enzyme purified from the Streptomyces strain can be a potential candidate for the treatment of thrombosis.

An organic solvent-tolerant alkaline lipase from Streptomyces sp. CS268 and its application in biodiesel production

In an effort to identify a microbial lipase that can catalyze transesterification reactions used in biodiesel production, an organic solvent-tolerant lipase was purified from Streptomyces sp. CS268. The molecular weight of the purified lipase was estimated to be 37.5 kDa by SDS-PAGE. The lipase showed highest activity at a temperature of 30°C and pH 8.0 while it was stable in the pH range 4.0 ∼ 9.0 and at temperatures ≤ 50°C. It showed the highest hydrolytic activity towards medium-length acyl chain p-nitrophenyl decanoate with Km and Vmax values of 0.59 mM and 319.5 mmol/mg/min, respectively. Also, the lipase showed non-position specificity for triolein hydrolysis. The purified lipase catalyzed transesterification reaction of soybean oil with methanol, suggesting that it can be a potential enzymatic catalyst for biodiesel production.

A novel Ca2+-dependent phospholipase D from Streptomyces tendae, possessing only hydrolytic activity

An extracellular phospholipase D (PLDSt) was purified from Streptomyces tendae by two successive chromatographic steps on Sepharose CL-6B and DEAE-Sepharose CL-6B. Molecular weight of the PLDSt was estimated to be approximately 43 kDa by sodium dodecyl sulfatepolyacrylamide gel electrophoresis. Maximal activity was at pH 8 and 60°C, and the enzyme was stable at or below 60°C and between pH 8 and 10, when assayed after 1.5 and 24 h, respectively. The enzyme activity had an absolute requirement of Ca2+, and the maximum activity was at 2 mM CaCl2. The Km and Vmax values for phosphatidyl choline were 0.95 mM and 810 µmol min−1 mg−1, respectively. More importantly, PLDSt could not catalyze transphosphatidylation of glycerol, L-serine, myo-inositol and ethanolamine, which have been extensively used to evaluate the activity. The result strongly suggests that PLDSt does not have the transphosphatidylation activity, thereby making it the first Streptomyces PLD possessing only hydrolytic activity. PLDSt may therefore be a novel type of PLD enzyme.