探索组蛋白 H1.1 和 H1.4 双链 DNA 相互作用的能量学。

Exploring the energetics of histone H1.1 and H1.4 duplex DNA interactions.

机构信息

Department of Chemistry, Mississippi State University, Box 9573, Mississippi State, MS 39762, USA.

Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA.

出版信息

Biophys Chem. 2014 Jan;185:32-8. doi: 10.1016/j.bpc.2013.11.007. Epub 2013 Nov 26.

DOI:10.1016/j.bpc.2013.11.007

PMID:24317196

Abstract

H1.1 and H1.4 bind tightly to both short DNA oligomers and to CT-DNA (Ka≈1×10(7)). Binding is accompanied by an unfavorable enthalpy change (∆H≈+22 kcal/mol) and a favorable entropy change (-T∆S≈-30 kcal/mol). The Tm for the H1.4/CT-DNA complex is increased by 9 °C over the Tm for the free DNA. H1.4 titrations of the DNA oligomers yield stoichiometries (H1/DNA) of 0.64, 0.96, 1.29, and 2.04 for 24, 36, 48, and 72-bp DNA oligomers. The stoichiometries are consistent with a binding site size of 37±1 bp. CT-DNA titration data are consistent with binding site sizes of 32 bp for H1.1 and 36 bp for H1.4. The heat capacity changes, ΔCp, for formation of the H1.1 and H1.4/CT-DNA complexes are -160 cal mol(-1) K(-1) and -192 cal mol(-1)K(-1) respectively. The large negative ΔCp values indicate the loss of water from the protein DNA interface in the complex.

摘要

H1.1 和 H1.4 与短 DNA 寡聚物和 CT-DNA 紧密结合（Ka≈1×10(7)）。结合伴随着不利的焓变（∆H≈+22 kcal/mol）和有利的熵变（-T∆S≈-30 kcal/mol）。H1.4/CT-DNA 复合物的 Tm 比游离 DNA 的 Tm 升高 9°C。H1.4 对 DNA 寡聚物的滴定得到 24、36、48 和 72-bp DNA 寡聚物的化学计量比（H1/DNA）分别为 0.64、0.96、1.29 和 2.04。这些化学计量比与结合位点大小为 37±1 bp 一致。CT-DNA 滴定数据与 H1.1 的结合位点大小为 32 bp 和 H1.4 的结合位点大小为 36 bp 一致。H1.1 和 H1.4/CT-DNA 复合物形成的热容变化，ΔCp，分别为-160 cal mol(-1) K(-1)和-192 cal mol(-1)K(-1)。大的负 ΔCp 值表明在复合物中从蛋白质-DNA 界面失去了水。