Binding to Chitosan of Multiple Forms of Glucoamylases from Aspergillus saitoi and Rhizopus sp.

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概要

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• Multiple forms of glucoamylases [EC 3.2.1.3] from Aspergillus saitoi and Rhizopus sp. were studied for their chitosan binding. Two forms of Aspergillus enzyme, Gluc M_1 and Gluc M_2,were bindable to chitosan, whereas three formes of Rhizopus enzyme, Gluc_1,Gluc_2,and Gluc_3,exhibited no significant binding; of these enzyme forms, Gluc M_1 and Gluc_1 are bindable to raw starch and Gluc M_1 and Gluc M_2 (less strongly) bindable to chitin. Both Gluc M_1(molecular weight (M.W.)90000) and Gluc M_2 (M.W. 70000), lacking the C-terminal portion (20000 dalton) of Gluc M_1,bound to chitosan within the narrow pH range from 6.0 to 7.0,with pH optima of 6.5-6.7,and ionic strength-dependently. The binding constants K of Gluc M_1 and Gluc M_2 to chitosan at pH 6.5 and 4℃ were 1.5×10^6 and 1.6×10^6M^<-1>, respectively. Upon denaturation and modification of Gluc M_1 with 6M guanidine hydrochloride and water-soluble carbodiimide, respectively, Gluc M_1 almost completely lost the ability to bind to chitosan. A very low concentration of soluble starch (2.95×10^<-4>%) inhibited binding of Gluc M_1 to chitosan by 50%. Chitosan-bound Gluc M_1 showed little enzymatic activity on maltose. These results indicate that a chitosan-binding domain is not aloways identical with a chitin-binding domain or a raw starch-binding domain and that in Gluc M_1 the binding domains for raw starch, chitin and chitosan are located in this order in the direction from the C-terminal to the N-terminal; the latter two are also contained in Gluc M_2. The chitosan-binding domains of the enzymes seem to include or to reside near the active sites.

• 社団法人日本薬学会の論文
• 1992-10-25

著者

• 高橋 朋子

  School Of Pharmaceutical Sciences Toho University

• 高橋 朋子

  Institute of Medical Chemistry, Hoshi University

• 鹿山 夏美

  Institute of Medical Chemistry, Hoshi University

• 鹿山 夏美

  Institute Of Medical Chemistry Hoshi University

関連論文

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• Fischer Indolization of Variously ortho-Substituted Phenylhydrazones (Fischer Indolization and Its Related Compounds. XXV)
• Binding to Chitosan of Multiple Forms of Glucoamylases from Aspergillus saitoi and Rhizopus sp.
• Different Binding Behavior to Chitin of Multiple Forms of Glucoamylases from Aspergillus saitoi and Rhizopus sp.
• Different Behavior towards Raw Starch of Two Glucoamylases from Aspergillus saitoi
• Differentiation of Two Types of Tryptophan Residues Related to Enzymatic Activity in a Glucoamylase from a Rhizopus sp. by N-Bromosuccinimide Oxidation in the Presence of Tris(hydroxymethyl)aminomethane and Maltitol
• Oxidation of Glucoamylase from a Rhizopus sp. with N-Bromosuccinimide
• Properties of Rhizopus sp. Glucoamylase Polymerized by Crosslinking with Glutaraldehyde
• Kinetic and Circular Dichroism Spectroscopic Comparison among Three Forms of Glucoamylase from a Rhizopus sp.
• Subsite Affinity of a Glucoamylase from Aspergillus saitoi
• Proteolytic Modification of a Glucoamylase from a Rhizopus sp.

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