- Contributions to nucleosome dynamics in chromatin from interactive propagation of phosphorylation/acetylation and inducible histone lysine basicities
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The effect of phosphorylation on the basicities of amines in histone H3 peptides and their acetylation kinetics is probed with a mild chemical acetylating agent. Phosphorylation of Ser-10 lowers the rate of chemical acetylation of Lys-9, Lys-14, and Lys-18 by methyl acetyl phosphate in that order consistent with a higher pKa of these Lys residues induced by phosphorylation; basicities increase up to 3 pKa units as a function of distance from Ser-10 phosphate. Enzymic acetylation of Lys residues with high pKa values in nucleosomes is also expected to be enhanced by phosphorylation, consistent with the known mechanism involving binding of protonated amines to N-acetyltransferases; fetal hemoglobin has a related linkage of increased basicity at a specific site, its acetylation, and a resulting decrease in subunit interaction strength. In the absence of a phosphate on Ser-10, the amines of Lys-9, Lys-14, and Lys-18 have lowered pKa values. Chemical acetylation of glycine and glycinamide have analogous kinetic profiles to the histone peptides but the phosphate inductive effect in histone H3 is more potent since the linkage between phosphorylation and acetylation is propagated with a range extending 9–10 amino acids in either direction from the phosphorylation site enhancing protonation of amino groups. We conclude that lysine amine basicities in histone tails are not static but inducible and variable due to a dynamic and immediate interaction between phosphorylation/acetylation that may contribute to inactive heterochromatin by compaction through such Ser phosphate–Lys amine electrostatic interactions and their relaxation by acetylation in euchromatin.
- Manning, Lois R.,Manning, James M.
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- Synthesis of water-soluble phosphinophenol for traceless staudinger ligation
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The traceless Staudinger ligation can be mediated in water without organic co-solvents if charged groups render the phenylphosphine reagent water soluble. Here the synthesis of a new water-soluble phosphine is presented based on a diphenylphosphino-phenol reagent. Staudinger ligation with this reagent and azido glycine amide showed conversion of 77%.
- Weisbrod, Samuel H.,Marx, Andreas
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experimental part
p. 787 - 789
(2010/07/02)
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- Interactions between Terminally Substituted Amino Acids in an Aqueous and a Non-Aqueous Environment. Enthalpic Interaction Coefficients in Water and in N,N-Dimethylformamide at 25 deg C
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Enthalpies of dilution of the N-acetyl amides of glycine, L-alanine, L-valine, L-leucine, and L-phenylalanine, dissolved in N,N-dimethylformamide (DMF) as a solvent have been measured at 25 deg C.The results obtained have been analyzed to give the enthalpic interaction (or virial) coefficients of the solutes and these are compared with information previously obtained in aqueous systems.There are marked differences in the interaction properties in the two solvents and, while the additivity approache of Savage and Wood is applicable to the solutes in water it is suitable for representing the interactions in DMF.A correlation is presented between the enthalpic second virial coefficients in DMF and the propensity of side-chains to be in proximity in globular proteins.
- Kent, Hilary E.,Lilley, Terence H.,Milburn, Peter J.,Bloemendal, Michael,Somsen, Gus
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p. 101 - 116
(2007/10/02)
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- Aqueous Solutions Containing Amino Acids and Peptides. Part 11.-Enthalpy of Dilution of Single and Binary Solute Solutions of N-Acetylglycine Amide, N-Acetyl-L-alanine Amide, N-Acetyl-L-valine Amide and N-Acetyl-L-leucine Amide at 298.15 K
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The enthalpies of dilution of aqueous solutions containing N-acetylglycine amide (G), N-acetyl-L-alanine amide (A), N-acetyl-L-valine amide (V) and N-acetyl-L-leucine amide (L) and equimolal solutions of G+A, G+V, G+L, A+V, A+L and V+L have been measured at 298.15 K.The results obtained have been used to calculate the pairwise enthalpy coefficients for like-like and like-unlike solute interactions.These coefficients have been compared with the predictions of the group additivity approach proposed earlier by Savage and Wood.The group additivity approach works well considering the experimental error and the standard deviation of the original correlations although it seems likely that some refinement of the group interaction parameters is required.
- Blackburn, G. Michael,Lilley, Terence H.,Walmsley, Elizabeth
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p. 915 - 922
(2007/10/02)
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