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Effect of aniline coupling on kinetic and thermodynamic properties of Fusarium solani glucoamylase.

Bhatti HN, Rashid MH, Nawaz R, Khalid AM, Asgher M, Jabbar A

Department of Chemistry, University of Agriculture, Faisalabad, 38040, Pakistan, hnbhatti2005@yahoo.com.

Purified glucoamylase (GA) from Fusarium solani was chemically modified by cross-linking with aniline hydrochloride in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) for 1 [aniline-coupled glucoamylase-1 (ACG-1)], 7 (ACG-7), and 13 min (ACG-13). The aniline coupling of GA had a profound enhancing effect on temperature, pH optima, and pK (a)'s of active site residues. The specificity constants (K (cat)/K (m)) of native, ACG-1, ACG-7, and ACG-13 were 136, 244, 262, and 208 at 55 degrees C for starch, respectively. The enthalpy of activation (DeltaH*) and free energy of activation (DeltaG*) for soluble starch hydrolysis were lower for the chemically modified forms compared to native GA. Proteolysis of ACGs by alpha-chymotrypsin and subtilisin resulted in activation.

Published 11 January 2007 in Appl Microbiol Biotechnol, 73(6): 1290-8.
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