285. Studies in the amino-sugars. Part I. A case of acyl migration

White, T. G.

doi:10.1039/jr9380001498

Cited by 19 publications

(3 citation statements)

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“…It was shown by White (42) and later by Fodor and Otvos (16) (32) for the substrates Ala-Ala-Lys-O-Me, Leu-Lys-0-Me, and PheLys-O-Me for ester hydrolysis and Z-Lys-Ala-Ala, Z-LysPhe-Ala, and Z-Lys-Leu-Ala for amide hydrolysis (where Z and Me are N-carbobenzoxy and methyl ester, respectively). Finally, the existence of an N-arylhydroxamic acid N,Oacetyltransferase (EC 2.3.1.56), which transfers the N-acetyl group of some aromatic acetylhydroxamates to the 0 position of some aromatic hydroxylamines, has recently been proven to exist as a unique and independent enzyme in a variety of mammalian tissues (38).…”

Section: Discussionmentioning

confidence: 99%

Evidence for N----O acetyl migration as the mechanism for O acetylation of peptidoglycan in Proteus mirabilis

Dupont

Clarke

1991

J Bacteriol

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0-acetylated peptidoglycan was purified from Proteus mirabilis grown in the presence of specifically radiolabelled glucosamine derivatives, and the migration of the radiolabel was monitored. Mild-base hydrolysis of the isolated peptidoglycan (to release ester-linked acetate) from cells grown in the presence of 40 , Following the lysis of invading microorganisms, mammalian tissues clear cellular debris, including peptidoglycan (PG), very rapidly through the action of the hydrolytic enzymes of either phagocytic cells or serum. However, in some instances, large-molecular-weight fragments of PG have been observed to persist and circulate in the host organism. These large PG fragments have been shown to induce diverse pathobiological and pathophysiological effects, many of which have been recently reviewed (36). Some of these include the induction of slow-wave sleep, complement activation, pyrogenicity, modulation of blastogenesis, and arthritogenicity. In vivo studies with the pathogens Staphylococcus aureus and Neisseria gonorrhoeae indicated that the phenomenon of PG persistence is directly attributable to the presence of numerous O-acetyl substituents on the glycan backbone (5,15,24,34,40). 0-acetylated PG has been observed in a number of bacteria, including many pathogenic species, both gram positive (e.g., S. aureus [17,41]) and gram negative (e.g., N. gonorrhoeae [40] and Proteus mirabilis [14]). 0 acetylation of PG occurs at the C-6 hydroxyl group of N-acetylmuramyl residues, producing the corresponding 2,6-diacetylmuramyl derivative. This modification to PG inhibits the hydrolytic activity of lysozymes (reference 13 and references therein), presumably through steric hindrance since the C-6 hydroxyl moieties of the substrate directly participate in its binding to the active-site cleft of the enzyme (3, 23). The PG of some species of eubacteria has been reported to be 0 acetylated up to 70%, thereby conferring both intrinsic and complete resistance to lysozyme hydrolysis (30). (1, 7), and the biological significance of this modification was discerned soon after (6). Whereas its role in resistance to muramidases and the consequences of such have been well documented, very little is known concerning the biosynthetic process involved with the 0 acetylation of PG. There is evidence to suggest that 0 acetylation occurs after nascent PG strands have been both attached and cross-linked to the preexisting sacculus (10,18,(26)(27)(28)39). By pulse-chasing radiolabelled N-acetyl-D-glucosamine (GlcNAc) into the PG of P. mirabilis, Gmeiner and Kroll (18) revealed that only non-O-acetylated PG subunits are incorporated into the growing polymer. It has also been observed that the 0 acetylation of PG continues in a cell-free biosynthetic system of P. mirabilis PG (30). , using a similar experimental strategy, obtained analogous results with N. gonorrhoeae. Indeed, searches for lipid (bactoprenyl)-linked N-acetylglucosaminyl-N,O-diacetylmuramyl pentapeptide precursors in either the cytoplasm or the cytoplasmic membrane pro...

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Section: Discussionmentioning

confidence: 99%

Evidence for N----O acetyl migration as the mechanism for O acetylation of peptidoglycan in Proteus mirabilis

Dupont

Clarke

1991

J Bacteriol

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“…This configurational pattern should reasonably be ascribed to the anomeric effect that would favor the axial disposition of the hydroxyl group. As strange as it may be, the literature points to the prevalent β configuration (equatorial anomeric hydroxyl) for the imines derived from 1 and 3 and aromatic aldehydes ( 7 – 10 ). − However, the opposite α-configuration for imines derived from 1 and their acetyl derivatives was postulated in previous work . From a synthetic viewpoint, such imines have been advantageously used not only to protect the amino group but also to switch the anomeric configuration of 2-amino-2-deoxyaldoses.…”

Section: Introductionmentioning

confidence: 99%

A True Reverse Anomeric Effect Does Exist After All: A Hydrogen Bonding Stereocontrolling Effect in 2-Iminoaldoses

Matamoros,

Pérez,

Light

et al. 2024

J. Org. Chem.

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The reverse anomeric effect is usually associated with the equatorial preference of nitrogen substituents at the anomeric center. Once postulated as another anomeric effect with explanations ranging from electrostatic interactions to delocalization effects, it is now firmly considered to be essentially steric in nature. Through an extensive research on aryl imines from 2-amino-2-deoxyaldoses, spanning nearly two decades, we realized that such substances often show an anomalous anomeric behavior that cannot easily be rationalized on the basis of purely steric grounds. The apparent preference, or stabilization, of the β-anomer takes place to an extent that not only neutralizes but also overcomes the normal anomeric effect. Calculations indicate that there is no stereoelectronic effect opposing the anomeric effect, resulting from the repulsion between electron lone pairs on the imine nitrogen and the endocyclic oxygen. Such data and compelling structural evidence unravel why the exoanomeric effect is largely inhibited. We are now confident, as witnessed by 2-iminoaldoses, that elimination of the exo-anomeric effect in the α-anomer is due to the formation of an intramolecular hydrogen bond between the anomeric hydroxyl and the iminic nitrogen, thereby accounting for a true electronic effect. In addition, discrete solvation may help justify the observed preference for the β-anomer.

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“…Only in Nos. 7,8,9 and possibly 14 do the acyl migrations proceed in an opposite sense, i.e., towards Ci.…”

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confidence: 99%

Notes: CL-C2 Acetyl Migration on Methylation of the Anomeric 1,3,4,6-Tetra-O-acetyl-D-glucopyranoses

Bonner¹

1959

J. Org. Chem.

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285. Studies in the amino-sugars. Part I. A case of acyl migration

Cited by 19 publications

References 0 publications

Evidence for N----O acetyl migration as the mechanism for O acetylation of peptidoglycan in Proteus mirabilis

Evidence for N----O acetyl migration as the mechanism for O acetylation of peptidoglycan in Proteus mirabilis

A True Reverse Anomeric Effect Does Exist After All: A Hydrogen Bonding Stereocontrolling Effect in 2-Iminoaldoses

Notes: CL-C2 Acetyl Migration on Methylation of the Anomeric 1,3,4,6-Tetra-O-acetyl-D-glucopyranoses

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