TY - JOUR TI - Crystal structures of substrate-bound chitinase from the psychrophilic bacterium Moritella marina and its structure in solution AU - Malecki, P.H. AU - Vorgias, C.E. AU - Petoukhov, M.V. AU - Svergun, D.I. AU - Rypniewski, W. JO - Acta Crystallographica Section D: Biological Crystallography PY - 2014 VL - 70 TODO - 3 SP - 676-684 PB - SN - 0907-4449, 1399-0047 TODO - 10.1107/S1399004713032264 TODO - chitin; chitinase; chitotetrose; ligand; oligosaccharide, article; chemistry; chitin-binding domain; enzyme specificity; enzymology; flexibility; genetics; hinge regions; Ig-like domain; ligand binding; metabolism; Moritella; multi-domain; point mutation; protein conformation; protein multimerization; psychrophilic; SAXS; small angle scattering; solution and solubility; TIM β/α-barrel; X ray crystallography; X ray diffraction, chitin; chitin-binding domain; chitinase; flexibility; hinge regions; Ig-like domain; ligand binding; multi-domain; psychrophilic; SAXS; TIM β/α-barrel, Chitinase; Crystallography, X-Ray; Ligands; Moritella; Oligosaccharides; Point Mutation; Protein Conformation; Protein Multimerization; Scattering, Small Angle; Solutions; Substrate Specificity; X-Ray Diffraction TODO - The four-domain structure of chitinase 60 from Moritella marina (MmChi60) is outstanding in its complexity. Many glycoside hydrolases, such as chitinases and cellulases, have multi-domain structures, but only a few have been solved. The flexibility of the hinge regions between the domains apparently makes these proteins difficult to crystallize. The analysis of an active-site mutant of MmChi60 in an unliganded form and in complex with the substrates NAG4 and NAG5 revealed significant differences in the substrate-binding site compared with the previously determined complexes of most studied chitinases. A SAXS experiment demonstrated that in addition to the elongated state found in the crystal, the protein can adapt other conformations in solution ranging from fully extended to compact. © 2014 International Union of Crystallography. ER -