Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a study of factors that influence the remaining secondary structure of reduced chicken eggwhite lysozyme, N-acetyl-D-glucosamine (NAG) and N,N'-diacetylchitobiose (di-NAG) were found to alter the circular dichroic (CD) spectrum of the reduced protein and its carboxymethyl derivative (Cml). Thus, negative ellipticities in the far u.v. were greater in the presence of the analogs, with NAG being the more effective. For Cml, curve fitting analysis of the CD data indicated an increased helical content in the presence of NAG by an average of 3% of the chain length, while beta-structure decreased by an equivalent amount. Other compounds structurally related to NAG produced no similar effects on the CD spectrum of Cml, nor were comparable effects of NAG in evidence on the Cm reduced derivatives of ribonuclease, chymotrypsin, wheat germ agglutinin, or alpha-lactalbumin. The effect therefore appears specific between NAG and Cml. Conversion of the tryptophan residue at Position 62 of Cml to the oxindolealanyl derivative prevented these effects of NAG, and this residue may therefore participate in the interaction. During a 4-day incubation at room temperature, the analog preserved the CD spectrum of Cml as well as its concentration. This effect was nearly specific when compared with other Cm reduced proteins and with other carbohydrates. Only one, N-acetyl mannosamine, was effective in preserving the concentration of Cml, but not the CD spectrum. Since D-glucosamine was entirely without effect on either the CD spectrum of Cml or on its change during incubation, the acetyl group appears essential for the NAG-Cml interaction. The specificity between NAG and Cml is tentatively accounted for in terms of interactions with the primary structure, rather than with the remaining secondary structure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Evidence for interaction of substrate analogs with chicken eggwhite lysozyme after exhaustive reduction of disulfide bonds. 651 17

A novel endo-beta-N-acetylglucosaminidase in the culture fluid of Mucor hiemalis isolated from soil was found to have transglycosylation activity. This endo-beta-N-acetylglucosaminidase, Endo-M, could liberate the complex type of asparagine-linked oligosaccharides by hydrolysis of diacetylchitobiose linkage from glycoproteins. The treatment of Endo-M with N-acetyl-glucosamine and asialotransferrin glycopeptide having the complex type of oligosaccharides resulted in the transfer of the released oligosaccharide from the glycopeptide to N-acetyl-glucosamine. The structure of the product after transfer was deduced to be (GlcNAc)2-Man-(Gal-GlcNAc-Man)2 by a combination method of pyridylamination and high performance liquid chromatography, and mass-spectrometry. The enzyme could transfer the complex type of oligosaccharide from asialotransferrin glycopeptide to bovine ribonuclease with the high-mannose type of oligosaccharide. This will lead to the construction of neoglycoproteins containing different types of oligosaccharides.
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PMID:Transglycosylation activity of Mucor hiemalis endo-beta-N-acetyl-glucosaminidase which transfers complex oligosaccharides to the N-acetylglucosamine moieties of peptides. 807 62