COMPOSITION OF PURIFIED MUCOPEPTIDE FROM THE WALL OF AEROBACTER CLOACAE

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Abstract
Molecular proportions of glucosamine, muramic acid, alanine, glutamic acid, and diaminopimelic acid in purified mucopeptide (MP) from the wall of Aerobacter cloacae NRC 492 have been estimated. Crude walls, obtained by fractional centrifugation of disintegrated log-phase cells, were treated with trypsin, ribonuclease, and pepsin to remove cytoplasmic contaminants. Of a number of protein solvents tested on the isolated walls, saturated aqueous sodium lauryl sulphate gave the purest MP in the highest yield. Molar ratios of glucosamine, muramic acid, alanine, glutamic acid, and diaminopimelic acid in hydrolyzates of the MP, corrected for the loss of hexosamines under the conditions of acid hydrolysis, were 2:2:3:2:2 respectively. These ratios indicate the presence of two types of peptide, with one peptide chain attached to each disaccharide unit. Analysis showed the absence of phosphate and therefore of teichoic acid from the purified MP.