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This article presents information on forthcoming papers to be published in coming issues of the periodical "European Journal of Biochemistry." Some of the papers are: "Localization of Histone HS in the Subunit Organization of Chromatin Using ImmunoeIectron Microscopy"; "Presence of an Amino Acid Oxidase in Photosystem II of Anacystis nidutans"; "Aldoximes: Active-Site Probes of Alcohol Dehydrogenases"; and "Quinone Reductases of Higher Plants."

The gycine-rich, arginine-rich histone from calf thymus contains 102 residues of amino acids, distributed as follows: Asp5, Thr7, Ser2, Glu6, Pro1, Gly17,. Ala7, Val9, Met1, Ile6, Leu8, Tyr4, Phe2, Lys10, Lys(Me)1, His2, Arg14. From a tryptic hydrolysate of Gly- and Arg-rich histone, 18 peptides were isolated by fractionation on a column of Chromobeads P followed by purification by paper electrophoresis and chromatography. The amino acid compositions of these peptides are reported. The sequence of 12 of these tryptic peptides has been established. The amino-terminal tryptic peptide is Ac-Ser-Gly-Arg. The carboxylterminal tryptic peptide is Thr-Leu-Tyr-Gly-Phe-Gly-GlyCOOH. [ABSTRACT FROM AUTHOR]

A mechanism of mitosis-specific enhancement of histone H3 phosphorylation was analyzed in vitro in terms of nucleosome structure. The incorporation of [32P]phosphate into DNA-bound H3 was approximately 5–7 times higher than in DNA-free H3 using the catalytic subunit of cAMP-dependent protein kinase. The two major N-terminal serine sites, including the mitosis-specific site (Serl0) and Ser28, were extensively phosphorylated in the DNA-bound forms. These phosphorylation patterns were identical to those of nucleosomal H3. In contrast, the H3 in DNA-free octamers was very slightly phosphorylated. The major site of H3 phosphorylation in DNA- free H3 was Thr118 in the C-terminus. Results indicate that DNA-binding is essential for the high level of mitosis-specific H3 phosphorylation, and that the nucleosome structure promotes H3 N-terminal phosphorylation b7 vitro It also suggests the possibility that HI prevents H3 phosphorylation during interphase of the cell cycle. [ABSTRACT FROM AUTHOR]

We have found that partial resolution of newly replicated nucleosomes can be achieved by rate zonal centrifugation through sucrose density gradients preformed in heavy water. Nucleosome samples were obtained from MH-134SC cells density labeled with 5-iododeoxyuridine in the presence of suitable isotopic precursors. The method is simple and can be performed under conditions that do not destabilize the nucleosome structure. This gave us an exciting opportunity to study the deposition sites of newly synthesized histones. Nucleosomes were obtained from cells pulse-labeled simultaneously with 5-iododeoxyuridine and [³H]lysine for the rate zonal analysis. Proteins in the resulting fractions were resolved by sodium dodecyl sulfate/polyacrylamide gel electrophoresis, and visualized by silver staining and fluorography. The distribution of newly synthesized H2A and H2B coincided closely with that of bulk nucleosomes. The distribution of newly synthesized H3 and H4 was shifted to the bottom sides of the bulk nucleosome peaks, but not so far as to the putative peaks of newly replicated (dense) nucleosomes. This means that newly synthesized histones are deposited on DNA in disproportionate amounts and that their sites of deposition are not restricted to newly replicated DNA. [ABSTRACT FROM AUTHOR]

A fractionation procedure for avian erythrocyte histones was devised to give the six known, reproducible histone fractions from a single nuclear preparation, with limited manipulation and little wastage. The proposed method includes selective, two-step acid extraction, followed by cation-exchange chromatography and exclusion chromatography. The fractions were identified by amino acid analysis and by starch gel electrophoresis. The method is flexible in scale and permits a continuous balance of compositions and activities in metabolic experiments. Factors contributing to the relative extractability of histones from chromatin in acid were considered. The essential role of this step was the separation of erythrocyte-specific, serine-rich histone V, and arginine-rich histones III, IV, which otherwise would be eluted together from Amberlite CG-50 by guanidinium chloride. Two other arginine-rich components, more easily eluted in chromatograms of other tissues, were absent from the usual extracts of mature erythrocytes. However, similar components were produced from histones III, IV by treatment with β-mercaptoethanol. The conditions for good resolution of sub-fractions of moderately lysine-rich histones and of arginine-rich histones by exclusion chromatography on Bio-Gel P-60 and P-30 were examined. Reversible adsorption appeared to be more significant than pore size of the gel; the sulphates of arginine-rich histones were resolved better than the chlorides. [ABSTRACT FROM AUTHOR]

The histones of group F2(b) have been fractionated by acetone precipitation and by column chromatography on carboxymethylcellulose at pH 9. The acetone precipitation method enables F2(b), prepared on a large scale by extraction methods, to be further purified in bulk, the resulting product having 84% N-terminal proline. The column chromatography on carboxymethylcellulose at pH 9 has given 5 main fractions, two of which contain over 25% acidic amino acids (or their amides) and over 24% basic amino acids. [ABSTRACT FROM AUTHOR]