212 



MACROMOLECULAR COMPLEXES 



was 1.28 and 1.24 per cent. These values are lower than that (2.1 

 per cent) reported bv Xorthcote and Home ( 1952), who stated that 

 their preparation contained no unbroken cells but was contaminated 

 bv small particles which were difficult to eliminate. 



The analytical data show that the clean cell-wall material con- 

 tains approximateb' 7 per cent protein, 85 per cent pohsaccharide, 

 and 3 per cent chitin. The high sulfur: protein ratio (2.1 per cent) 

 indicated that the protein may be a pseudokeratin t\"pe. Bv means 

 of two-dimensional paper chromatographv of h\drol\sates of cell- 

 wall material (6 X HCl for 16 hours at 110= C), the presence of 16 

 amino acids was detected. Representati\-e chromatograms from cell 

 walls of two strains of C. albicans are shown in Fig. 2 a and b. 



Fig. 3. Sedimentation pattern of primary glucomannan-protein (isolated 

 from bakers' yeast cell wall) in analytical ultracentrifuge. Duration of centrifu- 

 gotion noted on each exposure. Note indication of low molecular weight mate- 

 rial and apparent homogeneity of major peak. 



From preparations of clean cell wall, the major fraction ( approxi- 

 mately 75 per cent) was solubilized in 1 X KOH on warming to 

 about 50° C. The solubilized material was dialvzed against running 

 tap-water for 24 hours; on lyophilization, a white powder was ob- 

 tained, of which the bulk was readih" soluble in water. The water- 

 soluble fraction was found to contain pohsaccharide and protein, 

 and was assumed to be a mannan-protein complex on the basis of 

 the absence of the characteristic copper precipitate with Fehling's 

 solution. This view was reinforced bv ultracentrifugal studies which 

 revealed the material to be monodisperse at several concentrations 

 in water and in buffer. Representative sedimentation patterns are 

 showTi in Fig. 3, from which a sedimentation constant So,, = 4.3 

 X 10~^^ was calculated. 



Separation of Glucomannan-Proteins from Isolated Cell Walls. 

 The initial work on fractionation of cell-wall components led to 

 recognition of their polysaccharide-protein nature and made clear 

 the necessitv for removal of lipid components; subsequent work 



