2cjl: Difference between revisions

We describe the cloning, overexpression, purification, characterization, and crystal structure of chitinase G, a single-domain family 19 chitinase, from the Gram-positive bacterium Streptomyces coelicolor A3(2). Although, chitinase G was not capable of releasing 4-methylumbelliferyl from, artificial chitooligosaccharide substrates, it was capable of degrading, longer chitooligosaccharides at rates similar to those observed for other, chitinases. The enzyme was also capable of degrading a colored colloidal, chitin substrate (carboxymethyl-chitin-remazol-brilliant violet) and a, small, presumably amorphous, subfraction of alpha-chitin and beta-chitin, but was not capable of degrading crystalline chitin completely. The, crystal structures of chitinase G and a related Streptomyces chitinase, chitinase C [Kezuka Y, Ohishi M, Itoh Y, Watanabe J, Mitsutomi M, Watanabe, T & Nonaka T (2006) J Mol Biol358, 472-484], showed that these bacterial, family 19 chitinases lack several loops that extend the substrate-binding, grooves in family 19 chitinases from plants. In accordance with these, structural features, detailed analysis of the degradation of, chitooligosaccharides by chitinase G showed that the enzyme has only four, subsites (- 2 to + 2), as opposed to six (- 3 to + 3) for plant enzymes., The most prominent structural difference leading to reduced size of the, substrate-binding groove is the deletion of a 13-residue loop between the, two putatively catalytic glutamates. The importance of these two residues, for catalysis was confirmed by a site-directed mutagenesis study.

2CJL is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_coelicolor Streptomyces coelicolor] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Chitinase Chitinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.14 3.2.1.14] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2CJL OCA].  

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