208 MACROMOLECULAR COMPLEXES 



orators (1937, 1939, 1941). Exhaustive methylation of alkaline 

 solutions of the polysaccharide resulted in the formation of 2,3,4,6- 

 tetramethyl-, 3,4-dimethyl-, and 2,4,6-trimethylmannopyranose de- 

 rivatives. The occurrence of a 3,4-dimethyl derivative indicated a 

 double linkage to other components of the polymer. The evidence 

 was assessed as indicating that the polymer consists of a main chain 

 of 1,6-a-mannopyranose units to which are joined short side-chains 

 at the number 2 carbon of alternate rings. It should be pointed out 

 that the mannan employed in these studies was extracted from 

 bakers' yeast by boiling in 6 per cent NaOH solution for 8 hours. 

 Furthermore, it must be noted that the yield of mannose phenyl- 

 hydrazone from acid-hydrolyzed purified mannan was actually only 

 50 per cent of the theoretical amount. When a correction (based on 

 the recovery of only 82 per cent of the theoretical amount of man- 

 nose phenylhydrazone from pure mannose) was applied, the claim 

 was made that a minimum yield of 92 per cent of the theoretical 

 quantity of mannose was obtained on the hydrolysis of mannan. 

 Actually, even allowing correction for failure to recover the theo- 

 retical quantity of phenylhydrazone from a known solution of man- 

 nose, it would seem that the hydrolvsate of mannan did not contain 

 more than two-thirds of the theoretical amount of mannose. 



Wall Components of Mechanically Disintegrated Yeasts 



Publications appeared independently by Northcote and Home 

 (1952) and by Houwink et ah (1951) reporting the localization of 

 glucan, mannan, and chitin as components of isolated cell-wall frag- 

 ments. After mechanical rupture of cells, Northcote and Home iso- 

 lated washed cell walls of bakers' yeast. This material was free of 

 whole cells and cell debris and comprised the outer membranes of 

 the cell; it was completely Gram-negative in character, in contrast to 

 whole yeast cells which normally are intensely Gram-positive. The 

 cell wall was found to include nitrogenous substance and lipid and 

 to be composed principally of two polysaccharides— a mannan and a 

 glucan. Glycogen was not associated with cell walls isolated by this 

 procedure. Concurrent studies with the electron microscope showed 

 that the isolated wall material consisted of at least two layers, the 

 outer composed principally of glucan and the inner consisting of a 

 nitrogenous substance and mannan. The over-all composition of the 

 cell wall was taken to be: glucan 29 per cent, mannan 31 per cent, 

 protein 13 per cent (based only on determination of total nitrogen). 



