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The very lysine-rich histones(H1) from normal leucoctyes, myelocytic leukemia leucocytes, human and bovine colostrum, and bakers’ yeast were prepared according to the method of Johns, and Phillips and Johns. The purity of H1 fractions from various sources was checked by 15% polyacrylamide disc gel electrophoresis. The amino acid composition of each H1 fraction were determined by ion exchange chromatography procedure described by Spackman et al. These very lysine-rich histones were, further, subfractionated by chromatography on Amberlite IRC-50 with a shallow guanidinium chloride gradient. The results obtained were summarized as follows: 1) The yield of H1 fractions from various sources greatly differed each other. For example, in myelocytic leukemia leucocytes the levels of H1 was many times that of H1 in normal colostrum, suggesting that the levels of H1 is dependent on the function of tissue proper. 2) The electrophoretic mobility of individual very lysine-rich histone fractions gave similar patterns to those of corresponding fraction from various sources. 3) The chromatographic profiles of very lysine-rich histones from leucocytes, colostrum and bakers’ yeast revealed that there were significant differences in molecular species and relative amounts between various biological species. 4) Amino acid composition of histone H1 examined in the present studies, could be classified into two categories. One of these groups resemble the very lysine-rich histone found in eukaryotic cells, i.e., normal leucocytes, human and bovine colostrum. The other group, which may be confined to the myelocytic leukemia leucocytes and bakers’ yeast, exhibited quite lower Lys/Arg ratio which due to lesser contents of arginine residues in the subfraction molecule.
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