The Amino-Acid Sequence of Clupeine YII

The amino-acid sequence of clupeine YII was determined in 1966 [Ando and Suzuki, 1966 Suzuki and Ando, 1972 (1)]. 

A rechromatographed specimen of clupeine YII obtained unmodified by the chromatographic fractionation of TNP-(trinitrophenylated) whole clupeine (cf. Chap. VII. B. 3), has the molecular formula Arg2o Pro3 Ala2 2 Val2. This is based on the analysis of amino-acid composition and a molecular weight of about 5,000 for the hydrochloride as estimated by the DNP method (MW calculated from the amino acid composition 4,047 as a free base or 4,777 as the hydrochloride). 

By the DNP and PTC (phenylthiocarbamyl) methods, the N-terminal amino acid was determined to be proline and the N-terminal amino acid sequence to be H-Pro Arg Arg . The alternate action of carboxypeptidases B and A on clupeine YII followed by hydrazinolysis indicated that the amino-acid sequence at the C-terminal region was Pro Arg2 (Val, Ser) Arg4 Ala Arg4-OH. 

From the results described for both tryptic peptides and N- and C-terminal sequences, the following partial structure was derived for clupeine YII  

Chart VTTT-4 sets out the complete amino-acid sequence of clupeine YII as concluded from these results, combined with the information derived from the tryptic peptides. 

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