Abstract
Asparaginase (EC 3.5.1.1) activity was determined in non germinatingseeds and germinating seeds of five Egyptian cowpea (Vignaunguiculata) cultivars (Kareem 7, Dokki 331, Kafer El-Sheikh 1,Kaha 1 and Fodder). The specific activities of germinating seedsasparaginase in different cultivars were higher than the specificactivities of non germinated seeds of these cultivars. Asparaginasewas purified from Fodder cultivar germinating seeds ( the highestspecific activity) and resolved into three peaks with asparaginaseactivities by DEAE sepharose, designated by asp I, asp II and asp III.The molecular weight of asp II was 70 kDa for native enzyme usinggel filtration. By using SDS-PAGE electrophoresis, asp II hadmolecular weight about 35 kDa suggesting that a dimeric structure forasp II. AspII had a Km value 1.25 mM for asparagine and a pHoptimum at 8.0. Asp II had a temperature optimum and heat stabilityat 40 oC. The fodder cultivar asp II activity was specific for Lasparagineand did not hydrolyze D-asparagine. It is not specific forL-glutamine. Ni2+ and Co2+ had activator effects on asp II but othermetals ions had inhibitory effect.Key words: Cowpea , Isoenzymes, Asparagine, Glutamine, Antineoplastic effect.
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