title: Examination of the influence of C5-hydroxymethyl group and configurations of hydroxyl groups at C2, C3, and C4 stereocentres on the N-glycosidic torsion: synthesis and X-ray crystallographic investigation of N-(D-ribopyranosyl)alkanamides as N-glycoprotein linkage region analogs.
abstract: N-Linked glycosylation is not only present in eukaryotes but also occurs in archaea and bacteria and is mainly characterized by the β-glucosylamine linkage to the asparagine (GlcNAcβAsn). Earlier crystallographic studies aimed at understanding the structural significance of the linkage region constituents revealed that N-glycosidic torsion, ϕN is influenced considerably by variation in the glycan part as compared to the aglycon moiety. The ϕN value observed for XylβNHAc deviated maximum as compared to that of the model compound, GlcNAcβNHAc. The present work was undertaken to assess the influence of ribose on the N-glycosidic torsions and molecular assembly. Several ribopyranosyl alkanamides have been synthesized and crystal structures of three of them have been solved. A comprehensive crystal structure analysis of ribosyl alkanamides along with xylosyl and arabinosyl alkanamides showed the wide range of deviations in their ϕN values as compared to the negligible deviation shown by hexopyranosyl alkanamides. This study revealed the importance of C5-hydroxymethyl group and hydroxyl group configurations at C2, C3, and C4 stereocentres in controlling the N-glycosidic torsions.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India. Electronic address: amrisriv9@gmail.com.
authors.forename: Amrita
authors.initials: A
authors.lastname: Srivastava
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Manoharan
authors.initials: M
authors.lastname: Mathiselvam
authors.affiliation: Sophisticated Analytical Instrumentation Facility, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Babu
authors.initials: B
authors.lastname: Varghese
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Duraikkannu
authors.initials: D
authors.lastname: Loganathan
mesh_terms: D000577:Amides / Q000138:chemical synthesis* / Q000737:chemistry*; D000606:Amino Sugars / Q000138:chemical synthesis* / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006023:Glycoproteins / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D012266:Ribose / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000577:Amides; D000606:Amino Sugars; D006023:Glycoproteins; D006027:Glycosides; D012266:Ribose
keywords: Analogs; Hydroxymethyl group; Linkage region; N-Glycosidic torsion; X-ray crystallography