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The enzymatic hydrolysis of chitinous materials has been studied for almost a century. Since many early studies established that at least two major enzymes called chitinase that mainly yields N,N’‐diacetylchitobiose (GlcNAc)2, and 􀁉‐N‐acetylglucosaminidase that yields GlcNAc as the final product are required for the chitin catabolism for the most of microorganisms including marine bacteria such as Vibrio furnissii or V. cholera.
However, the chitin catabolic cascade is quite complex. Early study showed that chitin catabolism by the marine bacteria involves at least three signal transduction systems and many genes, several of which were molecularly cloned, and the corresponding proteins were characterized. This study demonstrates the purification and characterization of three unique enzymes: 1) a novel ATP‐dependent glucosamine kinase of V. cholerae encoded by a gene designated gspK. The protein, GspK (31.6 kDa), was purified to apparent homogeneity from recombinant Escherichia coli. The kinase can be used to specifically determine micro quantities of GlcN in acid hydrolysates of glycoconjugates; 2) a novel phosphorylase of V. furnissii. The gene, chbP, was cloned into E. coli; the enzyme, ChbP (89‐kDa protein), was purified to apparent homogeneity, and characterized kinetically; and 3) the identification of bglA, a gene contiguous to gspK in a presumptive large chitin catabolic operon. BglA was molecularly cloned into E. coli, and the protein BglA was overexpressed and purified to apparent homogeneity (65 kDa). The Henrissat algorithm places BglA sequence in Family 9 of the glycosidases, suggesting it is an endoglucanase. However, the results demonstrated that BglA is an exoenzyme yielding Glc at each cleavage step. To resolve this apparent discrepancy, detailed kinetic studies were conducted with cellotetraose. Only exoglucanase activity was detected. The function of this enzyme in V. cholerae remains to be determined, especially because our strain of this organism does not utilize cellobiose. In addition, diversity of chitinolytic enzymes in microorganisms is discussed.

저자

• Jae Kweon PARK [ Department of Biotechnology, The catholic University of Korea, Bucheon, Gyeonggi-do 420-743, Korea. Dept. of Biology, The Johns Hopkins University, Baltimore Maryland USA. ]

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간행물

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• 간행물명

  한국생물공학회 학술대회

• 간기

  반년간

• 수록기간

  1985~2013

• 십진분류

  KDC 476 DDC 576