484 



A. TSUGITA AND 11. !• H \K\ KKL-COXRAT 



B. AMINO ACID SEQUENCE 



'I'lif aiiiiiu) acid cDiiipo.-itioii of llic TAIN' protein has Ween (l('tci-iiiiiu'(l 

 by several means. Recently the composition has been (h'linitdy estab- 

 lished by ion exchange chromatogi'ai)hy, using the autnnialic amino acid 

 analyzer (Tsugita and Fraenkel-Conrat, 1960). Almost tiie same (mjiii- 

 position was deduced also by Wittmann and Braunitzcr (19o9) by a 

 summation of the compositions of the separated peptides resulting from 

 tryptic digestion of the virus protein. The two analyses agreed well 

 except for one isoleucine residue. Nine residues of isolcucine were 

 detected after sufficiently long hydrolysis of the protein, as well as in the 



TABLE I 

 Ami.xo Acid Comtosition of N.^vtural Strains (jf TMV" 



sequential study at Berkeley, and that this number rather than eight 

 was correct was later confirmed by Anderer (1962). The main problems 

 in amino acid analysis reside now in the purity of the material, and in 

 the rate of the liberation or decomposition of the amino acids during 

 hydrolysis rather than in the accuracy of the analysis. Table I shows 



