Composition of the cell wall and other fractions of the autolyzed yeast form of Histoplasma capsulatum

Comparison of two strains ofHistoplasma capsulatum yielded data differing only in quantification, and the constituents observed and identified were galactose, glucose, mannose, glucosamine and amino acids. A comparison of hydrochloric acid and formic acid hydrolyses ofH. capsulatum fractions indicated hydrochloric acid to be of more value than 88 per cent formic acid hydrolysis for composition analyses. The removal of formyl esters from formic acid hydrolysates was found necessary and was accomplished byN HCl hydrolysis for 30 min. Two derivative artifacts were observed with formic acid hydrolysis; D-1, which was refractory to subsequent HCl hydrolysis, and D-2, which disappeared after HCl hydrolysis. Another artifact, D-3, was observed with 6N HCl hydrolysis of histoplasma cell wall fractions. The following conditions of hydrolysis were found to be useful: (1) glucose release was measured after hydrolysis inN HCl for 4 hr; (2) glucosamine release was measured after hydrolysis in 6N HCl for 9 hr; (3) amino acid release was accomplished by 6N HCl hydrolysis for 18 hr; and (4), hexoses released were determined by gas liquid chromatography (GLC) after hydrolysis in bothN HCl and in 88 per cent formic acid for 24 hr, followed byN HCl for 30 min. Several different types of carbohydrate polymers have been reported in the parasitic yeast form ofH. capsulatum. There is general agreement on the occurrence of amino acids as protein (8, 12, 13), chitin (7, 19) and several hexoses, including glucose and glucosamine, which are found in cell wall polymers (7, 8, 11–16, 19, 20, 24). The presence of uronic acid was also reported (14, 15), but not confirmed, by Domer, Hamilton & Harkin (8), and mannose was not found by all investigators (12). We undertook a study of graded acid hydrolyses and of composition analysis of the autolysis products of the yeast form by various procedures in order to add further to the above information.