The effect of organic compounds on the chitinase activity the dissociation constant calculation of the Chitinase-metallic ion complex

The effect of some organic compounds on the activity of chitinase from Serratia marcescens has been investigated. Among these compounds, 1,10-phenanthroline was found to be an inhibitor and ethanol - an activator of the chitinase activity; -’ dipyridyl and Zn2+ do not take any effect on the chitinase activity. In this investigation, the dissociation constant of an chitinase-metalic ion complex (K1) and the inhibition constant (K2) have been estimated with K1 = 0.1 mcM and K2 = 2.667 mM.
Nội dung trích xuất từ tài liệu:
The effect of organic compounds on the chitinase activity the dissociation constant calculation of the "Chitinase-metallic ion" complexJournal of Chemistry, Vol. 41, No. 2, P. 110 - 114, 2003 The effect of organic compounds on the chitinase activity The dissociation constant calculation of the Chitinase-metallic ion complex Received 12-3-2002 Naoyoki Taniguchi , Yoshitaka Ikeda1, Tran Dinh Toai2 1 1 Department of Biochemistry, Osaka University Medical School, Japan 2 Institute of Chemistry, National Center for Natural Science and Technology of Vietnam Summary The effect of some organic compounds on the activity of chitinase from Serratia marcescens has been investigated. Among these compounds, 1,10-phenanthroline was found to be an inhibitor and ethanol - an activator of the chitinase activity; - ’ dipyridyl and Zn2+ do not take any effect on the chitinase activity. In this investigation, the dissociation constant of an chitinase-metalic ion complex (K1) and the inhibition constant (K2) have been estimated with K1 = 0.1 mcM and K2 = 2.667 mM. I - Introduction mechanism is important for the design of understanding properties of this enzyme [3, 4]. Chitinases (EC 3.2.1.4) belong to numbers A typical colorimetric substrate forof glycosyl hydrolases. These numbers related assaying exochitinase activity is p-nitrophenyl -enzymes (482 sequences) corresponding to 52 N-acetyl-beta-D-glucosaminide (pNP-beta-EC entries of the I.U.B classification system GlucNAc) and for assaying endochitinasehave been classified into 45 families. Chitinases activity is p-nitrophenyl- -D-N,N,N-triacetyl-catalyze the hydrolysis of chitin, an insoluble chitotrise, respectively [5].linear (1,4)-linked polymer of N-acetyl- The chitinase activity is effected by manyglucosamine (GlcNAc), and are critical for the organic compounds (argifin, allosamidin,normal development of insects. argadin [6, 7]), heavy metal ions (Ag+, Hg2+, On the basis of amino acid sequence, five Fe2+, Fe3+), and chemical modified agents (NaI,known classes of Chitinases are grouped into NBS).two glycosyl hydrolase families [1, 2]. The exochitinase is a metalloenzyme, and Family 18 consists of class III and class V its activity is inhibited by 1,10-phenanthroline.Chitinases found in a wide range of organisms The zinc plays an important role in functioningincluding bacteria, plants, animals, fungi and of exochitinase [8].viruses. Family 19 consists of class I, II and IV In order to understand the mechanism ofChitinases and is found only in plants. chitinase action, we had tried to find a The enzyme structures and hydrolysis dissociation constant of a chitinase-metallicmechanisms for two families appear to be quite ion complex and an influence of some organicdifferent. The knowledge of the reaction compounds on the chitinase activity. 110II - Determination of dissociation equation (1 - 4), if these constants K1, K2 are constant of a enzyme-metallic known. There are several solutions to determine ion complex the dissociation constant of enzyme-metallic ion complex1. Enzymatic kinetic method for Determin- A total initial concentration of enzyme can ation of dissociation constant of an be summarized: enzyme-metallic ion complex [E]0 = [E] + [E*] (5) It is suggested that, the enzyme will lose its Equation (2 - 5) can be summarized by theactivity if metallic ion goes out of the enzyme following:active center. It is represented by the followingscheme: K1 [E ] = [E ] ([E ] [E ])K/(1 + [I ] / K * 1 ) ...