Open AccessThe Amino Acids of the Cell Wall of Mycobacterium tuberculosis var. bovis, Strain BCG
Author(s) -
WietzerbinFalszpan Juana,
Das Bhupesh C.,
Gros Claude,
Petit JeanFrançois,
Lederer Edgar
Publication year - 1973
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1973.tb02637.x
Subject(s) - peptidoglycan , diaminopimelic acid , muramic acid , glutamic acid , lysozyme , amino acid , biochemistry , cell wall , alanine , chemistry , muramidase , diamino acid , pronase , enzyme , trypsin , gene sequence , gene , phylogenetic tree
A detailed investigation of the amino acids of cell wall preparations obtained by various methods from the BCG strain is reported.1 “Non‐peptidoglycan” amino acids represent about 15% of the weight of crude, delipidated cell walls (Table 1); trypsin‐chymotrypsin treated, delipidated cell walls contain mainly the peptidoglycan amino acid alanine, glutamic acid and meso ‐2,2′‐diaminopimelic acid, the ratio Ala/A 2 pm being 1.5 and the ratio Glu/A 2 pm being 2.3, as compared with the expected values of 2 and 1 for a classical peptidoglycan; there are, however, equal molar amounts of d ‐glutamic acid and diaminopimelic acid and the excess of glutamic acid is the l ‐form. 2 After enzymatic solubilization of the peptidoglycan by lysozyme or by Myxobacter AL 1 enzyme 90% of the peptidoglycan amino acids are found in the soluble part; this has been fractionated on Sephadex G‐50 and in most of the fractions obtained the ratio Glu/A 2 pm is 1, as expect ed, but the ratio Ala/A 2 pm is closer to 1 than to 2, indicating some other, not yet defined cross link to diaminopimelic acid. 3 The insoluble residue obtained after lysozyme or Myxobacter AL 1 enzyme digestion contains a poly ( l ‐glutamic acid); partial acid hydrolysis allows the solubilization of various l ‐glutamic acid oligopeptides, which have been studied by mass spectrometry, after N ‐acetylation and per‐methylation; Fig. 3 shows a partial mass spectrum obtained from a peptide containing 6 or 7 glutamic acid residues, proving the sequence Glu‐Glu‐Glu‐Glu; pyroglutamic acid is observed in all spectra, indicating that at least the N ‐terminal glutamic acid residue is in α‐linkage. The intact polymer could not be isolated, but the largest fragment obtained has an average chain length of eleven glutamic acid residues. 4 The presence of l ‐glutamic acid polymers seems to be restricted to human and bovine strains of Mycobacteria and to Mycobacterium kansasii.