Chemical modification and fluorescence spectrum of inulinase from Aspergillus ficuum
1. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China; 2. School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China; 3. School of Life Science and Chemical Engineering, Huaiyin Institute of Technology, Huai＇an, Jiangsu 223001, China）
Abstract：In this study, the effects of amino acid side chain groups in exoinulinase and endoinulinase from Aspergillus ficuum on inulinase activity were studied by chemical modification, using N - bromossuc- cinimide （ NBS）, diethyl pyrocarbonate （ DEPC）, butanedione （ DIC）, chloramine - T（ Ch - T）, ethyl- carbodiimide （EDC）, phenylmethanesulfonyl fluoride （PMSF） , and dithiothreitol （DTT） as modification reagents. The results indicated that Tryptophan and carboxyl-containing amino acids residues were involved in active sites of exoinulinse and endoinulinase. The number of Tryptophan residue was estimated to be one for endoinulinase and two for exoinulinase by the method of Zou＇s plot. Histidine residue may be essential for active site of inulinases. It was further suggested by fluorescence spectrum analysis that compared to Tryptophan residue in exoinulinase, Tryptophan residue in endoinulinase was located in a more polar environment and was more sensitive to the change of environment, which showed greater exposure, indicating that exoinulinase and endoinulinase had different conformations.
2009, Vol. 30 
