Studies on the asparaginolytic activity of the brown-pigmented streptomycetes

Twenty-eight brown-pigmented streptomycetes were isolated from different fertile Egyptian soils. Screening was carried out according to their asparaginolytic activity under static culture condition on glycerol- L-asparagine [GA] medium. Results revealed that FS-39 isolate gave the highest asparaginolytic activity. Therefore, it was selected and subjected to complete identification. The cultural, morphological and physiological characteristics of this isolate indicated that it belongs to Streptomyces phaeochromogenes. The effects of nutritional and environmental conditions on the asparaginase activity of Streptomyces phaeochromogenes FS-39 were studied. Data revealed that the maximal, yield of L-asparaginase from this strain can be obtained by growing it on glycerol-L-asparagine yeast extract [GAY] medium containing [w/v] 2.0% Glycerol, 0.2% L-asparagine, 0.1% yeast extract, 0.1% K[2]HPO[4].3H20, 0.0001% FeSO[4].7H[2]0, 0.0001% MnCl[2]. 4H[2]0, 0.0001% ZnSO[4].7H[2]O which was initially adjusted to pH 7.0, inoculated by 2% [v/v] of homogenized spore suspension [containing approximately 3.2x10[7] spores/ml] of 3 days old culture on starch nitrate medimi and incubated at 30°C for 7 days under static culture condition

Puriffication and characterization of L-asparaginase produced by Streptomyces phaeochromogenes FS-39

An L-asparaginase [EC.3.5.1.1] produced by Streptomyces phaeochromogenes FS-39 was purified and characterized. After initial ammonium sulfate fractionation [50-70% saturation], the enzyme was purified by consecutive column chromatography on ion exchange [DEAE-Cellulose] and Sephadex G-200 filtration. The 67.2 fold purified enzyme thus obtained has the specific activity of 179.14 units mg protein super [-1] with an over all recovery of 17.7%. The enzyme was characterized by demonstration of optimum activity at 35°C and pH 8.5. It was stable for 180 min. at 30-35°C and 7 days at 4°C [refrigerator] and pH range from 8.0 to 9.0. The enzyme activity was slightly stimulated by Mg supper [2+], Fe super [2+] and Ca super [2+] cations, but Na-azid and EDTA did not exert any effect on the enzyme activity. Hg super [2+], Ag super [+] and Cu super [2 +] cations as well as L-cysteine, iodine, KCN and iodoacetic acid strongly inhibited the enzyme, but Zn super [2+], KMnO4 and super [2+] potentially slightly inhibited the enzyme activity. L-aspartic acid was competitive inhibitor