Polysaccharide-Protein Complexes of 

 Yeast Cell Walls' 



Walter J. Nickerson,- G. Falcone,'^ and Gian Kessler ^ 



Rapid advances in our knowledge of the chemical composition of 

 the cell walls of microorganisms have resulted from the develop- 

 ment of techniques for obtaining cell-wall preparations free from 

 other cellular components, and from the establishment of criteria of 

 homogeneity of cell- wall preparations. Microbial cells may be rup- 

 tured by mechanical or enzymatic procedures, and the broken cells 

 may be separated from intact cells by centrifugation at low speed. 

 By differential centrifugation and repeated washing of the cell-wall 

 fraction, clean cell-wall preparations may be obtained that appear 

 morphologically uniform in the electron microscope. The dialyzed 

 and lyophilized wall preparations may be fractionated and analyzed 

 with a fair degree of confidence that the results will not be negated 

 by contamination from cytoplasmic debris. 



The cell wall comprises about 30 per cent of the dry weight of 

 bakers' or brewers' yeast, and includes a fraction which is remark- 

 ably resistant to chemical or enzymatic attack. In fact, the insoluble 

 residue obtained on toluene autolysis of yeast, and the insoluble 

 residue remaining after treating yeast with 1 N NaOH at 100° C, 

 retains much of the shape of a yeast cell. Early investigations drew 

 attention to the polysaccharide nature of this residue, and deduced 

 that the cell wall of yeast comprised "yeast cellulose" and "yeast 

 gum." 



' Contribution from the Institute of Microbiology, Rutgers, The State University, 

 New Brunswick, New Jersey; experimental work described supported in part by 

 grants from the U. S. Public Health Service. The authors express their appreciation 

 to Pauline E. Holbert (Institute of Microbiology, Rutgers, The State University) for 

 her collaboration in the preparation of electron micrographs, and to Dr. D. E. 

 Williams ( Merck & Co., Rahway, N. J. ) for his collaboration on sedimentation 

 analyses. 



^ Rutgers, The State University, New Brunswick, N. J. 



^ Istituto di Patologia Generale, Universita, Naples, Italy. 



" Department of Biochemistry, University of California, Berkeley, Calif. 



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