Purification and quantitative chemical analysis of cell wall peptidoglycans of Leptotrichia buccalis

Abstract

Peptidoglycans of L. buccalis ATCC 14201 and ATCC 19616 were isolated by extraction with sodium dodecyl sulfate [SDS] and subsequent digestion of the SDS-insoluble residue with proteases and .alpha.-amylase. Cell wall fractions obtained by SDS extraction and protease digestion were highly contaminated by a glucose polymer. The polyglucose was removed by .alpha.-amylase treatment; the peptidoglycans were left behind. Analyses with amino acids and amino sugars of the cell wall fractions and peptidoglycan specimens revealed that D-glutamic acid, D-alanine, L-alanine, meso-2,6-diaminopimelic acid (A2pm), muramic acid and glucosamine were the prinicipal components. The dinitrophenylation method revealed that about half of the A2pm residue had a free amino group; analysis by hydrazinolysis showed that small parts of alanine and A2pm were located at the C terminal. Evidently, one of the amino groups of the A2pm residue at 1 strand of the stem peptide subunit cross-linked to the carboxyl group of alanine of the neighboring strand. The peptidoglycans of L. buccalis belong to the A1.gamma. type of the classification by Schleifer and Kandler.