Partial structural analysis of a highly basic low molecular weight protein from rat testis

Automated Edman degradation of a testis-specific basic protein isolated from the rat gave the following NH 2-terminal sequence of amino acids: ▪ Cleavage of the native protein with cyanogen bromide produced two fragments which were purified by gel filtration. Amino acid analysis of the smaller fragment revealed it to be the NH 2-terminal undecapeptide resulting from cleavage at Met 11. The partial sequence analysis of the intact protein coupled with compositional analyses of these cyanogen bromide peptides indicate that the basic testis protein contains 24 basic amino acids and a single methionine in a sequence of 54 amino acids.