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See detailThe peptide N alpha-(L-alanyl-D-isoglutaminyl)-N epsilon-(D-isoasparaginyl)-L-lysyl-D-alanine and the disaccharide N-acetylglucosaminyl-beta-1,4-N-acetylmuramic acid in cell wall peptidoglycan of Streptococcus faecalis strain ATCC 9790
Ghuysen, Jean-Marie ULg; Bricas, E.; Leyh-Bouille, Martine et al

in Biochemistry (1967), 6(8), 2607-2619

A major portion of the cell wall peptidoglycan in Streptococcus faecalis is composed of the disaccharide tetrapeptide β-1,4-N-acetylglucosaminyl-N-acetylmuramyl-Nα-(L-alanyl-D-isoglutaminyl)-L-lysyl-D ... [more ▼]

A major portion of the cell wall peptidoglycan in Streptococcus faecalis is composed of the disaccharide tetrapeptide β-1,4-N-acetylglucosaminyl-N-acetylmuramyl-Nα-(L-alanyl-D-isoglutaminyl)-L-lysyl-D-alanine. The tetrapeptides are cross-linked through single D-isoasparaginyl residues extending from the C-terminal D-alanine of one tetrapeptide unit to the Nє-terminal L-lysine of another. It is the first time that the occurrence of an isoasparaginyl residue in a natural product has been described. The Streptomyces SA en-dopeptidase cleaves D-alanyl-D-isoasparaginyl linkages and is thus the first enzyme known to hydrolyze D-D peptide bonds. Treatment of the disaccharide Nα-( L-alanyl-D-isoglutaminyl)-N є-(D-isoasparaginyl)- L-lysil-D-alanine with 10 equiv of NaOH at 37° for 1 hr results in deamidation of the isoasparaginyl residue together with migration of the aspartyl-lysine peptide bond giving rise to a mixture of Nє-(β-aspartyl)- and N є-(α-aspartyl)lysyl peptides. Under the same alkaline treatment, the N-acetylmuramyl residue undergoes a lactyl elimination which results in the production of acyl peptides and a Morgan-Elson prochromogenic compound, without hydrolysis of the glycosidic linkage. This conversion, interpreted to be the result of a β elimination, also occurs in the other disaccharide peptide monomers previously isolated from Staphylococcus aureus, Micrococcus roseus, and Streptococcus pyogenes. [less ▲]

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See detailThe Cell Wall Peptidoglycan of Bacillus megaterium KM. I. Studies on the Stereochemistry of α,α'-Diaminopimelic Acid
Bricas, E.; Ghuysen, Jean-Marie ULg; Dezelee, P.

in Biochemistry (1967), 6(8), 2598-2607

α,α'-Diaminopimelic acid (DAP) occurs in the wall peptidoglycan of Bacillus megaterium KM predominantly in the form of its meso isomer (about 85% of the total residues) and, in minor amounts, in the form ... [more ▼]

α,α'-Diaminopimelic acid (DAP) occurs in the wall peptidoglycan of Bacillus megaterium KM predominantly in the form of its meso isomer (about 85% of the total residues) and, in minor amounts, in the form of its DD isomer. The amino groups on the L carbon of the meso-DAP residues are involved in peptide linkages to the glutamic acid residues. Most of the amino groups on the D carbon of the meso-DAP residues are free; some of them are substituted, thus probably serving to cross-link peptide subunits. These amino groups can be liberated by a Streptomyces endopeptidase. None of the DD-DAP residues have amino groups free. Moreover, these groups are not liberated by endopeptidase treatment. The peptidoglycan upon enzymatic degradation yields mainly two fractions. A major fraction is composed of disaccharide peptide monomer subunits containing only the meso isomer of DAP. A second minor fraction is composed of disaccharide peptide oligomers containing both meso and DD isomers of DAP. The meso-DAP residues isolated as monodinitrophenyl derivatives from both fractions have optical rotations and optical rotatory dispersions identical with that of synthetic monodinitrophenyl-meso-DAP obtained by dinitrophenylation of the amino group on the D carbon. The assignment of the DD configuration to the DAP residues which are not meso rests upon the optical rotatory properties of their bisdinitrophenyl derivatives. [less ▲]

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