Histone, calf-thymus

In this connection, it must also be borne in mind that the deoxyribonucleic acids subjected to analysis have probably not been homogeneous. Deoxyribonucleic acids have been fractionated by making use of their different solubilities in normal saline,186 by extracting thymus nucleo-his-tone with sodium chloride solutions of increasing concentration,187 by ion-exchange,187 and also by adsorption of the polynucleotide onto histone immobilized on a kieselguhr support.123 It is possible, however, that these are artefacts, since it has been shown that deoxyribonucleic acid fractions extracted from calf-thymus nucleohistone may or may not vary in composition according to the previous treatment of the material.188... 

The fluorescence of purified histones has been studied by several different groups, 90 95) with the most detailed studies being on calf thymus histone HI. Histone HI, which binds to the outside of core particles, contains one tyrosine and no tryptophan. This protein exhibits a substantial increase in fluorescence intensity in going from a denatured to a folded state.<90) Collisional quenching studies indicate that the tyrosine of the folded HI is in a buried environ-ment.(91) Libertini and Small(94) have identified three emissions from this residue when in the unfolded state with peaks near 300, 340, and 400 nm. The 340-nm peak was ascribed to tyrosinate (vide infra), and several possibilities were considered for the 400-nm component, including room temperature phosphorescence, emission of a charge transfer complex, or dityrosine. Dityrosine has the appropriate spectral characteristics, but would require... 

Histone HI from the fruit fly Ceratitis capitata has two tyrosine residues. Jordano et al.(<)2> have observed two differences from calf thymus HI (1) the apparent quantum yield does not increase on protein folding and (2) there is a pH- and conformation-dependent shoulder at 340 nm in the emission spectrum. This group has attributed this 340-nm emission to tyrosinate.(97) Their studies demonstrate that the folding of histone HI from C. capitata is pH and ionic strength dependent. The possibility of tyrosinate formation at neutral pH is discussed in greater detail in Section 1.5.2. 

The HI histone from calf thymus shows three different emission bands... 

Protein A24 is histone H2A into which the peptide ubiquitin is covalently attached via its carboxy-terminal end to the e-amino of lysine 119 of H2A (Goldknopf et al., 1977). A24 is a constituent of nucleo-somes and is present to the extent of 10% of calf thymus H2A (Busch... 

Fig. 10. A. Acetic acid-urea-triton-X-100 polyacrylamide gel electrophoresis [15] of the histones used to reconstitute 208-12 nucleosome arrays consisting of recombinant H2A.Z (lane 2) or recombinant H2A.1 (lane 3). Lanes 1 and 4 respectively are chicken erythrocyte and calf thymus histones used as markers [42]. B. Ionic strength (NaCl concentration) dependence of the average sedimentation coelRcient (s2o,w) of reconstituted 208-12 nucleosome arrays containing either H2A.1 (O) or H2A.Z ( ) [42]. The dotted line represents the behavior of a 208-12 complex reconstituted with chicken erythrocyte histones [406]. [Reproduced from Abbott D.W. et al. (2001) I. Biol. Chem. 276, 41945-41949, with permission from The American Society for Biochemistry and Molecular Biology.]...

Paik, W.K and Kim, S. (1973) Enzymatic Demefhylation of Calf Thymus Histones. 

ATP -I- histone <1, 2, 3> (<1> calf thymus histone II-S, poor substrate... 

S ATP -I- [DNA-directed eukaryotic RNA polymerase II subunit Ila] (<4> distinct from other protein phosphokinases, transfers about 20 phosphates to the heptapeptide repeats Pro-Thr-Ser-Pro-Ser-Tyr-Ser in C-terminal domain of MW 220000 subunit of RNA-polymerase II [7] <4> substrates are RNA-polymerase II subunits of wheat germ, soy bean, pea and human [7] phosphorylates predominantly Ser-residues [1-3,5,7] <1> kinase CTDKl almost exclusively phosphorylates Ser-residues [5] <1> kinase CTDK2 phosphorylates to a lesser extent Thr-resi-dues [1] <3-5> phosphorylates to a lesser extent Thr-residues [1,5,7] <1> phosphorylates Ser- and Thr-residues equally [6] <1,3,5> phosphorylates not Tyr-residues [1,6] <1> kinase CTDKl 33 mol phosphate per mol IIA-subunit [5] <1> kinase CTDK2 40-50 mol phosphate per mol IIA-subunit, i.e. 1 phosphate per heptapeptide repeat [5] <4> no substrate is GTP [7] <2,4> no substrates are CTP and UTP [3,7] <2> no substrates are dTTP and AMP-PNP [3] <4> no substrates are bovine serum albumin and calf thymus histone [7] <5> no substrate is phosvitin... 

Figure 11. Summary of cleavage specificity of deuterolysin from A. oryzae toward calf thymus histone H14.

Other name Aspergillus sojae neutral proteinase II Microbial neutral proteinase II Preferential cleavage of bonds with hydrophobic residues in Pi also Asn3- -Gln and Glys-J.-Ser bonds in insulin B chain. For calf thymus histone H4, high activity towards... 

Several studies have reported on ellipticine- or elliptinium-DNA interactions. The effects of elliptinium on chromatin in vitro or in the nuclei are an unfolding of the overall structure and a disorganization of the partial structure of the core, leading to an unwrapping of the DNA from the histone core 181). The kinetics and thermodynamics of ellipticine and ellipticinium (protonated ellipticine) binding to calf thymus DNA have been carefully investigated 182). It was... 

The e-N-methyllysines have been found in histones (see DeLange and Smith, 1971, 1974), cytochromes c (see DeLange et al. 1970), flagellin (see Glazer et al. 1969), ribosoraal proteins (Comb et al. 1966) and muscle proteins (see Paik and Kim, 1971 for a review). In some proteins (e.g. calf thymus histone III) e-N-monomethyllysine, e-N-dimethyl-lysine and e-N-trimethyllysine are all three present, whereas in other proteins only one derivative (e.g. cytochromes c) or two of the derivatives (e.g. calf thymus histone IV) are present. Methylated lysines can also be formed in proteins by chemical modification in vitro ( 3.1.1.3). 

A more complicated example is afforded by histone H4 from calf thymus. The TV-terminal serine residue is TV-acetylated and may be O-phosphorylated. e-TV-... 

Calf (thymus chromatin) Histone redistribution No data + Polacow et al. 1976... 

CD spectra (200—350 nm) of calf thymus chromatin were compared with those of pure DNA in solution. Some of the differences observed (above approximately 250 nm) were attributed to conformational changes in the bound DNA, in which a large tilting of the bases may occur [(373) and refs, cited therein]. Previously, similar conclusions had been reached on the basis of ORD measurements on native nucleohistone and on nucleohistone dissociated either fully or partially into DNA and histone [(374) see also (375—379)]. CD studies on the state of DNA in native and partially deproteinized gander erythrocyte chromatin and of complexes of ethidium bromide with these systems were reported (380). 

The amino acid sequences of four histones (H2A, H2B, H3, and H4) are remarkably similar among distantly related species. For example, the sequences of histone F13 from sea urchin tissue and calf thymus differ by only a single amino acid, and H3 from the garden pea and calf thymus differ only In four amino acids. Minor histone variants encoded by genes that differ from the highly conserved major types also exist, particularly in vertebrates. 

Calf thymus histone H4 (IV, F2al) is phosphorylated by a specific enzyme on His-18 and His-75. The sequences around these residues are (76) ... 

Protein (arginine) methyltransf erase has been purified approximately 34-fold from calf thymus (202). The enzyme has a pH optimum of 7.4 and a Km of 2.1 X 10 6M for S-adenosyl-L-methionine, which is at least 100 times lower than the in vivo level of this co-factor. The enzyme may have a molecular weight as high as 1-2 million (206). Although myelin protein is the best substrate for the enzyme (207), it has ben shown to methylate various histones, bovine serum y-globulin, trypsin inhibitor, and pancreatic ribonuclease (208). 

Protein (lysine) Methyltransferase. The enzyme which methylates lysine residues of proteins was named protein methylase III by Paik and Kim (210). Its recommended trivial name is protein (lysine) methyltransferase (S-adenosyl-L-methionine protein-lysine methyltransferase EC 2.1.1.25). Protein (lysine) methyltransferase was found in all rat organs examined and was localized exclusively in the nuclei. Paik and Kim (210) solubilized the enzyme from an acetone powder of calf thymus and purified it 1.3-fold. The enzyme was difficult to work with in the solubilized state, since its activity was lost on overnight storage at either — 10° or 3°C. The enzyme was most effective in methylating histones, especially arginine-rich histone. Denaturation of histone by heating at 100°C for 30 min had no effect on the rate at which protein-lysine) methyltransferase methylated it. Poly lysine and protamine were methylated at slower rates, but horse heart cytochrome c did not serve as substrate. Km for S-adenosyl-L-methionine was 3.0 X 10"6M. 

The amino sequence around the c-N-acetyllysine residues is known in several histones. In calf thymus histone H4 the sequence is (76) ... 

Acetylation occurs near the N-terminal end of the protein and near the sites of methylation (see section on Methylation and Demethylation) of these histones. Residue 16 is the major site of acetylation in both pea and calf thymus histones H4, but other sites may also be acetylated in some cases, particularly residue 8 in pea histone (226) ... 

DeLange et al. (227) suggested that die recognition site for acetylation of calf thymus histones H3 and H4 by one of the acetylation enzymes might be -Lys-X Y-Arg-Lys- Other enzymes with different recognition sites were also indicated by the data. 

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