Semi-purified immobilized esterase, isolated from the seed of Pisum sativum, was found to be an efficient biocatalyst for the facile esterification of pharmaceutically important carboxylic acids. The partially purified esterase precipitated using ammonium sulfate was immobilized using sodium alginate method. After incubation, the immobilized beads so formed were found to be spherical with an average size 3 mm. Immobilized esterase (Km: 580 ug, Vmax: 350 ug/min) to be tested for the esterification of aromatic carboxylic acids was incubated separately with methanol containing benzoic acid, 4-amino-2-chlorobenzoic acid, salicylic acid, and ethanol containing 4-aminobenzoic acid, respectively, at room temperature with constant stirring. Activity of free and immobilized esterase was measured with synthetic substrate, 4-nitrophenyl acetate. The reaction progress was monitored by thin layer chromatography (Hexane: Ethyl acetate) with successive time intervals. The corresponding esters methylbenzoate, 4-amino-2- chloromethylbenzoate, methylsalicylate, and 4-aminoethylbenzoate were analyzed with spectroscopic techniques and determination of physical constants. This confirmed the ability of esterase to transform organic acids smoothly into desired esters. The present studies demonstrated the suitability of preparation and promising procedure for the green synthesis of aromatic esters. Highly purified esterase of P. sativum will afford wide futuristic scope for large scale production of pharmaceutically and/or industrially important products.
Key words: Bioesterification, Partial purification, Immobilized Esterase, Pisum sativum
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