Conformational effects of organic solvents on histone complexes

Abstract

Changes in the conformations of H3-H4, H2A-H2B, and the core histone complex brought about by the addition of organic solvents have been examined by circular dichroism spectroscopy. All three complexes assume increased alpha helicity with increasing amounts of the organic solvent. An amount of secondary structure equal to that obtained in phosphate-buffered 2 M NaCl solution can be induced in low-salt solutions of the complexes by the addition of 40-50% ethylene glycol, 50% glycerol, or approximately 2% hexafluoro-2-propanol. H3-H4 was found to be somewhat more flexible than H2A-H2B in its response to changes in solvent polarity. Upon being heated, H3-H4 and the core histone complex both undergo irreversible alpha leads to beta transitions in 50% ethylene glycol under low-salt conditions, while H2A-H2B undergoes an essentially reversible alpha leads to beta random-coil transition under the same conditions. These results are discussed in terms of the dynamics of the nucleosome particle.

Effects of pH, Temperature, and Sucrose on Benzyl Alcohol-Induced Aggregation of Recombinant Human Granulocyte Colony Stimulating Factor

“…However, the effects of benzyl alcohol on tertiary structure of rhGCSF could be monitored by near UV CD spectroscopy. Near UV CD spectroscopy has been used extensively to monitor protein tertiary structure at different temperatures26,27 and with varying solvent conditions28,29 without any interference on the protein signal. Also, near‐UV CD can be used reliably for understanding the direct effects of benzyl alcohol on the protein and in the absence of aggregation because of the low protein concentrations (1.0 mg/mL) required for the analysis and the relative speed of acquisition of spectra.…”

Chemical properties of alcohols and their protein binding sites

“…TFE is a poor hydrogen bond acceptor compared with ethanol but a much better hydrogen bond donor (table 1, frequency shift data). It also has more potent biological effects than ethanol at receptors activated by acetylcholine [50] and adenosine triphosphate (ATP) [51] and in protein folding paradigms [52][53][54]. However, TFE is more polar than ethanol (dielectric constant, − 26.6 vs. 24.3), which contradicts the Meyer-Overton rule.…”

“…For a given alcohol, there is generally a close correspondence between its behavioral effects (intoxication) and its effects on protein structure [6,9,11,28]. Thus, butanol is more potent than propanol or ethanol at inducing conformational changes, and halogenated alcohols, such as TFE and HFIP (which, incidentally, is a major metabolite of the experimental anesthetic, sevoflurane), produce the greatest effects on protein structure [52][53][54]. Therefore, a better understanding of the anesthetic properties of alcohols may be achieved by defining more precisely how alcohols alter protein structure.…”

Supramolecular aggregates formed by L-glutamic acid-oligomers: SANS and SAXS studies of the hydrogen bonded self-assembly

“…Proteins, which may be regarded as one class of very complex amphiphilic molecules, are compacted into giant selforganized systems. Beaudette et al10,11 have found that a conformational change upon formation of a giant aggregate occurs in complexes of histone proteins. Doty et al12 presented high molecular weight poly-cbenzyl-L-glutamate (PBLG) as a model molecule for proteins which take up an a-helical conformation, even in some organic solvents, as well as in the solid state.…”