Abstract
Since the discovery of its anti-tumor properties, L-glutaminases have been in prime focus and microbial sources of the enzyme are sought. In the present study L-glutaminase from Streptomyces avermitilis was optimized and the results revealed that the optimum pH, temperature, inoculum size, incubation period and NaCl concentration for enzyme production were pH 8, 28°C, 5 ml/100 ml media v/v, 5 days and 3% NaCl respectively. Glucose and sodium nitrate proved to be the best carbon and nitrogen sources respectively. The enzyme was purified 8.02 fold and the apparent molecular weight of the enzyme was found to be 50 kDa. The optima pH and temperature for the enzyme were (7.0 and 8.0) and 30°C respectively. The enzyme was more stable at 4% NaCl and its activity increased when NaCl and MgSO4 were added as metal salts. The enzyme also showed high stability in the presence of different oxidizing agents. Key words: L-Glutaminase, Streptomyces avermitilis, anti-tumor, purification.
Highlights
Enzymes are biocatalysts produced by living cells to bring about specific biochemical reactions generally forming parts of the metabolic processes of the cells
L-Glutaminase activity was identified by formation of a pink zone around S. avermitilis colonies due to accumulation of ammonia which is resulted in change in pH indicator color from yellow to pink due to the increase in pH value which is caused by Lglutamine utilization (Hymavathi et al, 2009)
The results reveal that in S. avermitilis the L-glutaminase productivity increased as the inoculum size increased until it reached its maximum productivity (12.61 U/ml) at 5 ml
Summary
Enzymes are biocatalysts produced by living cells to bring about specific biochemical reactions generally forming parts of the metabolic processes of the cells. L-Glutaminase has a central role in mammalian tissues (Errera and Greenstein, 1949) These are generally categorized as the kidney type and liver type glutaminases and both types have been purified and characterized (Svenneby et al, 1973; Curthoys et al, 1976; Heini et al, 1987). A parallel interest on microbial L-glutaminases stemmed from its applications in food of biotechnology, microbial L-glutaminases found newer applications in clinical analysis and even in manufacture of metabolites. This led to the extensive studies on L-gluta-. Since the sources for L-glutaminases are limited, the search for potential microbial strains that hyper produce the enzyme with novel properties for their industrial production is being pursued all over the world (Prabhu and Chandrasekaran, 1995). The production of extracellular L-glutaminase by Streptomyces avermitilis was reported under submerged culture and attempts were made to study the optimization of L-glutaminase production, its purification and characterization from Streptomyces avermitilis
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