الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 270 |  |  |
| | | from | 270 | | |
Abstract
L-asparaginase from the cotyledons of Cicer arietinum expressed maximum activity at the 5th day of germination. Jasmonic acid induced L-asparaginase at the lower concentrations and the optimum concentration for enzyme induction was 100 μM. GA3 at 100 μM induced the enzyme activity whereas ABA suppressed the activity. L-asparaginase was purified using ammonium sulphate, DEAE-cellulose column, Sephadex G200 and Sephacryl S300 with final specific activity of 75 units mg-1 protein. L-asparagine was the substrate whereas D-asparagine and L-aspartic were inhibitors for the enzyme. The enzyme was inhibited by the various tested inhibitors: cyanide, fluoride, azide, tungstate and malonate. The polyols namely: ethylene glycol, glycerol, erythritol, xylitol and sorbitol protected the enzyme from inactivation at 60 ºC. Maltose and sucrose offered partial protection for L-asparaginase activity. Glucose offered little protection. Trehalose was the best protector. PEG, Ca2+, sarcosine and glycol chitosan increased the enzyme stability at 60 ºC. Both the free and immobilized L-asparaginase was stable against digestion by chemotrypsin and trypsin. The results show that, both -SH and histidyl groups are essential for L-asparaginase catalysis.