4hp0

Publication Abstract from PubMed

4-O-beta-Di-N-acetylchitobiosyl moranoline (2) and 4-O-beta-tri-N-acetylchitotriosyl moranoline (3) were produced by lysozyme-mediated transglycosylation from the substrates tetra-N-acetylchitotetraose, (GlcNAc)4, and moranoline, and the binding modes of 2 and 3 to hen egg white lysozyme (HEWL) was examined by inhibition kinetics, isothermal titration calorimetry (ITC), and x-ray crystallography. Compounds 2 and 3 specifically bound to HEWL, acting as competitive inhibitors with Ki values of 2.01 x 10(-5) and 1.84 x 10(-6) m, respectively. From ITC analysis, the binding of 3 was found to be driven by favorable enthalpy change (DeltaHr degrees ), which is similar to those obtained for 2 and (GlcNAc)4. However, the entropy loss (-TDeltaSr degrees ) for the binding of 3 was smaller than those of 2 and (GlcNAc)4. Thus the binding of 3 was found to be more favorable than those of the others. Judging from the Kd value of 3 (760 nm), the compound appears to have the highest affinity among the lysozyme inhibitors identified to date. X-ray crystal structure of HEWL in a complex with 3 showed that compound 3 binds to subsites -4 to -1 and the moranoline moiety adopts an undistorted (4)C1 chair conformation almost overlapping with the -1 sugar covalently bound to Asp-52 of HEWL (Vocadlo, Davies, G. J., Laine, R., and Withers, S. G. (2001) Nature 412, 835-838). From these results, we concluded that compound 3 serves as a transition-state analogue for lysozyme providing additional evidence supporting the covalent glycosyl-enzyme intermediate in the catalytic reaction.

A novel transition-state analogue for lysozyme, 4-O-beta-tri-N-acetylchitotriosyl moranoline, provided evidence supporting the covalent glycosyl-enzyme intermediate.,Ogata M, Umemoto N, Ohnuma T, Numata T, Suzuki A, Usui T, Fukamizo T J Biol Chem. 2013 Mar 1;288(9):6072-82. doi: 10.1074/jbc.M112.439281. Epub 2013, Jan 9. PMID:23303182^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.