1chk

STREPTOMYCES N174 CHITOSANASE PH5.5 298K

spinqualitylabelsall models 1chk, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1chk is a 2 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [CHIS_STRSN] Aids in the defense against invading fungal pathogens by degrading their cell wall chitosan. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed We report the 2.4 A X-ray crystal structure of a protein with chitosan endo-hydrolase activity isolated from Streptomyces N174. The structure was solved using phases acquired by SIRAS from a two-site methyl mercury derivative combined with solvent flattening and non-crystallographic two-fold symmetry averaging, and refined to an R-factor of 18.5%. The mostly alpha-helical fold reveals a structural core shared with several classes of lysozyme and barley endochitinase, in spite of a lack of shared sequence. Based on this structural similarity we postulate a putative active site, mechanism of action and mode of substrate recognition. It appears that Glu 22 acts as an acid and Asp 40 serves as a general base to activate a water molecule for an SN2 attack on the glycosidic bond. A series of amino-acid side chains and backbone carbonyl groups may bind the polycationic chitosan substrate in a deep electronegative binding cleft. X-ray structure of an anti-fungal chitosanase from streptomyces N174.,Marcotte EM, Monzingo AF, Ernst SR, Brzezinski R, Robertus JD Nat Struct Biol. 1996 Feb;3(2):155-62. PMID:8564542 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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