POLYSACCHARIDE-PROTEIN COMPLEXES 



211 



Cell-wall fragments were isolated by differential centrifugation 

 and repeated washing with distilled water, 8.5 per cent sucrose 

 solution, and phosphate buffer (pH 7.4, O.IM). Washing with 

 sucrose and with buflFer served to eliminate completely the small 

 particles which, in water, sediment along with the cell-wall frag- 

 ments. After about 50 repetitions of washing and differential cen- 

 trifugation, a fraction consisting exclusively of cell-wall material was 

 obtained (Fig. 1). This was lyophilized, and the analvtical data are 

 based on material prepared in this manner. The nitrogen content of 

 cell-wall preparations from two different batches of bakers' yeast 



lARG 



o 



(^^VAL-MET 



PHE 



LYS 



HXE 



LEU- 

 ILEU 



n-BUTANOL-ACETIC ACID-WATER 

 (b) 



medium containing lO-"^ M Na2Se03. Note spot (X) in (b), corresponding to 

 cysteic acid of (a), presumed to be a selenium-containing analogue. 



