title: Two catalytic domains of Chlorella virus CVK2 chitinase.
abstract: VChti-1 chitinase encoded by the Chlorella virus CVK2 contained two catalytic domains belonging to family 18 glycosyl hydrolases. The first catalytic domain on a C-terminal-truncated derivative of vChti-1 generated exclusively chitobiose from chitotetraose, chitohexaose, and colloidal high-molecular mass chitin in the enzyme reaction, a typical characteristic of an exochitinase. In contrast, N-acetylglucosamine was produced from chitobiose as well as from chitooligosaccharides by the second catalytic domain on an N-terminal-truncated derivative of vChti-1. Therefore, the second domain possessed N-acetylglucosaminidase activity as well as endochitinase activity. The presence of two catalytic domains with different enzymatic properties in the viral enzyme seems to be necessary for hydrolyzing natural substrates in a cooperative fashion.
authors.affiliation: Department of Molecular Biotechnology, Graduate School of ADSM, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Hiramatsu
authors.forename: M
authors.initials: M
authors.lastname: Fujie
authors.forename: S
authors.initials: S
authors.lastname: Usami
authors.forename: K
authors.initials: K
authors.lastname: Sakai
authors.forename: T
authors.initials: T
authors.lastname: Yamada