Abstract

Introduction: L-methioninase (METs) catalysez the disintegration of methionine, an essential amino acid into ammonia, α-Ketoglutarate and methanethiol. L-methionine has a central role in the metabolism of all macromolecules, control of gene expression, cytoprotection and membrane integrity. This enzyme has been extensively studied from a wide range of organisms, including plants, terrestrial and marine microbes. Aim of the work: The aim of the present study was to produce, purify, immobilized and comparing the characteristics of the free and immobilized L-methioninase from Fenugreek. Material and methods: L-methioninase was purified using ammonium sulphate precipitation, DEAE-cellulose and Sephadex G200. The final specific activity was 34.5 units mg-1 protein and 61.3-fold. The enzyme was immobilized on both Ca-alginate and chitosan. Also, the effect of treatment with three phytohormones including jasmonic acid, gibberellic acid and kinetin was studied. Results: The results in the present investigation exhibited that chitosan was better than Ca-alginate in the immobilization efficiency. Increasing the time of immobilization elevated the immobilization efficiency with Ca-alginate and chitosan. The enzyme was reused seven cycles and after 7 cycles it retained appreciable activity particularly with chitosan. The enzyme was desorbed highly from Ca-alginate than chitosan. The optimum pH values were 8 and 9, respectively for the free and the immobilized enzyme. The optimum temperatures were 35 and 40ºC, for the free and immobilized L-methioninase respectively. Treatment with the three phytohormones activated the enzyme with different rates. In conclusion: We can conclude that L-methioninase was purified from fenugreek plants with appreciable specific activity. The enzyme was immobilized on Ca-alginate and chitosan. The later was being the best support. The immobilized enzyme was reused seven cycles with maintaining considerable activities.