Chitinase structure

The published filarial chitinases show a distinct modular domain structure (Fig. 10.3). The first 17-22 amino acids serve as a cleavable signal sequence, indicating that the enzymes are secreted or are components of the outer membrane. The catalytic domain, essential for the degradation of... 

Fuhrman, J.A., Lee, J. and Dalamagas, D. (1995) Structure and function of a family of chitinase isozymes from Brugian microfilariae. Experimental Parasitology 80, 672-680. 

The crystal structure of a pentamer of GlcNAc residues, representing the chitin polymer (poly-/l-(l-4)-GlcNAc), boimd to the chitinase enzyme ChiB from Serratia marcescens, revealed a narrow, timnel-like active site in the center of the TIM barrel fold [167]. Several conserved residues near the center of the site, which are important in catalysis, interact with the substrate via hydrogen bonds, while interactions farther from the center depend on van der Waals interactions. The sugar in the - 1 subsite adopts a boat conformation, presumably due to interactions with these critical active-site residues. 

Overall, these chitinase inhibitors provide an interesting example of peptide-carbohydrate mimicry. As described above for several other systems, mimicry consists of a mixture of structurally mimetic interactions and other favorable interactions with the receptor. Of the structurally mimetic interactions, the mimicry by argifin of the N-acetyl group, and part of the pyranosyl... 

Fig. 2 X-ray co-crystal structure of diketopiperazine-chitinase complex (PDB ID IWIP). Dike-topiperazine inhibitor is shown as yellow sticks, and the receptor binding site is shown as transparent surface. The hydrogen bonding with the key Trp97, Tyr214, and water (cyan ball) is shown as yellow dots...

Houston DR, Synstad B, Eijsink VGH, Stark MJR, Eggleston IM, van Aalten DMF (2004) Structure-based exploration of cyclic dipeptide chitinase inhibitors. J Med Chem 47(23) 5713-5720... 

Diketopiperazines are rather abundant in marine bacteria. In spite of their simple structures, some are reported to have herbicidal [100] (8, 9), chitinase... 

Metraux, J.P., Burkhart, W., Moyer, M., Dincher, S., Middlesteadt, W., Williams, S., Payne, G. Ryals, J. (1989). Isolation of a complementary DNA encoding a chitinase with structural homology to a bifunctional lysozyme/chitinase. Proceedings of the National Academy of Sciences (USA) 86, 896-900. 

Shinshi, H., Neuhaus, J.M., Ryals, J. Meins, F. (1990). Structure of a tobacco endochitinase gene evidence that different chitinase genes can arise by transposition of sequences encoding a cysteine-rich domain. Plant Molecular Biology 14, 357-68. 

Plants also produce structurally related enzymes (chitinases) that catalyse the hydrolysis of chitin (Table 12.2) and hence damage chitin-based insect integuments. Class I chitinases are basic enzymes with an jV-terminal hevein-related CBD and vacuole-targeting C-terminal signals whereas Class II enzymes are acidic proteins lacking these CBD and vacuole-targeting domains. Class IV chitinases are variously basic and acidic extracellular proteins with... 

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