5] 



STUDIES ON PROTEIN MICROSTRUCTURE 



81 



Table 4 



AMINO ACID COMPOSITION (RESIDUE NUMBERS) 



OF BOVINE CHYMOTRYPSINOGEN AND 



TRYPSINOGEN 



further shows that the residue numbers of the basic amino acids, particularly 

 of arginine and histidine, in chymotrypsinogen and trypsinogen (4 and 2, 

 and 2 and 3 respectively) are well suited for our comparative studies, as well 

 as the relatively low number of cysteine (half-cystine) residues (9-10 and 

 11-13, respectively). At the outset we again carried out a statistical com- 

 parison of the amino acid composition of total hydrolysates of the cysteic 

 acid peptide fractions isolated from the partial hydrolysates of the per- 

 formic acid — oxidized proteins by means of Amberhte IRA-4B.^ Table 5^ 

 in which the amino-acid compositions of the total hydrolysates of several 

 proteins and those of the corresponding cysteic acid peptides are set out, 

 indicates that the degree of resemblance between the amino acid composition 

 of hydrolysates obtained from the cysteic acid peptides of chymotrypsino- 

 gen and trypsinogen, respectively, is about the same as that between the 

 composition of the two whole proteins. At the same time, however, the 

 table reveals significant differences between the composition of hydrolysates 

 of the cysteic acid peptides of the two enzymogens on the one hand, and 

 of the remaining proteins on the other. 



The statistical evaluation of the composition of the cysteic acid peptide 

 fractions naturally gives only very approximate information about resem- 

 blances in the structure of the proteins under examination; the results have 



Fps 



