1re2
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(New page: 200px<br /><applet load="1re2" size="450" color="white" frame="true" align="right" spinBox="true" caption="1re2, resolution 2.3Å" /> '''HUMAN LYSOZYME LABELL...)
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Revision as of 23:23, 20 November 2007
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HUMAN LYSOZYME LABELLED WITH TWO 2',3'-EPOXYPROPYL BETA-GLYCOSIDE OF N-ACETYLLACTOSAMINE
Overview
Among the three kinds of the 2',3'-epoxypropyl beta-glycoside of, disaccharides (GlcNAc-beta1,4-GlcNAc, Gal-beta1,4-GlcNAc, and, Man-beta1,4-GlcNAc), the derivative of N-acetyllactosamine, (Gal-beta1,4-GlcNAc-Epo) caused the dual labeling of human lysozyme (HL), most efficiently. The labeled HL was crystallized and analyzed by X-ray, diffraction methodology. The X-ray analysis located the two, Gal-beta1,4-GlcNAc-Epo moieties inside the catalytic cleft of HL. The, attachment sites were the side-chain carboxylate groups of the catalytic, residues Glu35 and Asp53 in HL. The first Gal-beta1, 4-GlcNAc-Epo moiety, occupied virtually the same position as observed in the HL labeled with, single Gal-beta1,4-GlcNAc-Epo molecule. The second Gal-beta1,4-GlcNAc-Epo, moiety was recognized via the carbohydrate-carbohydrate interaction with, the first Gal-beta1, 4-GlcNAc-Epo moiety in addition to the, protein-carbohydrate interaction with the "right-side" catalytic cleft of, HL through a number of hydrogen bonds including water-mediated ones as, well as many van der Waals contacts. The two N-acetylglucosamine residues, stacked with each other, while the two rings of galactose residues, approximately shared the same plane. The dual labeling with two, Gal-beta1,4-GlcNAc-Epo molecules was supposed to have occurred, sequentially, which was accompanied with the alteration to the pKa of, Glu35 derived from the esterification of Asp53 in the first labeling. Both, asymmetric carbons in the connection parts between HL and, N-acetyllactosamine moieties showed the same stereoconfiguration derived, from the reaction with (2'R) stereoisomer concerning the epoxide group in, the labeling reagent. The results demonstrated that the HL labeled with, single Gal-beta1,4-GlcNAc-Epo was functional as a novel, N-acetyllactosamine-binding protein, and the second labeling was performed, by way of the first-ligand assisted recognition of the second ligand.
About this Structure
1RE2 is a Single protein structure of sequence from Homo sapiens with GOL as ligand. Active as Lysozyme, with EC number 3.2.1.17 Full crystallographic information is available from OCA.
Reference
Dual affinity labeling of the active site of human lysozyme with an N-acetyllactosamine derivative: first ligand assisted recognition of the second ligand., Muraki M, Harata K, Sugita N, Sato K, Biochemistry. 1999 Jan 12;38(2):540-8. PMID:9888793
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