THE KERATINIZATION PROCESS 



241 



These products are amorphous, the larger structural elements character- 

 istic of the original material not being rebuilt. 



This method has been much developed recently by Gillespie and 

 Lennox (1953 and 1955) who have made an extensive study of the elect- 

 rophoretic behaviour of several kerateines and their alkylated forms 

 (Gillespie, 1960). Their practice is to reduce in thioglycollic acid at pH 

 105 at 59°C to obtain several extracts (extracts A-E) at this pH, which 

 prove to be very heterogeneous, then to raise the pH to 12-3 when larger 

 amounts of an electrophoretically pure component " kerateine-2 " are 

 removed. The extracts are stabilized by blocking the SH groups by 



H 



GLYALA VAL LEU LEU SER THR MET 



LYS ARC HIS ASP CLU NH 2 CY5 



Fig. 100. Comparison of the amino acid composition of a keratin de- 

 rivative (stippled) with that of merino wool from which it was extracted. 

 Figures represent percentages of total nitrogen. Reconstructed from data 

 given by Simmonds (1954). 



alkylation. Simmonds and Stell (1956) have analysed these extracts and 

 demonstrated some striking differences in composition between whole 

 wool kerateine-2 and extract A. Extract A is characteristically higher in 

 cystine than kerateine-2. Figure 100 permits a visual comparison between 

 the composition of kerateine-2 and the wool from which it was obtained 

 and Table 17 shows the amino acid composition of the extract. 



At 50°C 65% of wool can be dissolved in 0-1 M thioglycollate at pH 12-6 

 and seven components can be detected electrophoretically. The minor 

 components can be removed by five 20 min extractions at a lower pH 

 (10*5) leaving the residue from which the major component (41% of wool) 

 can be obtained by a further extraction at pH 12*3 (kerateine-2). 



