title: [Characteristics of sulfhydryl groups of histone H3 from the calf thymus using mercury-containing nitroxyl radicals].
abstract: The interaction between total histone and deoxyribonucleoprotein (DNP) preparations from calf thymus with mercury-containing nitroxyl radicals in low ionic strength solutions, 2 M NaCl and urea was investigated. It was found that the label is rapidly incorporated into the SH-groups of histone H3 to produce characteristic EPR signals. Titration of SH-groups within DNP demonstrated that in low ionic strength solutions only one SH-group (presumably, the SH-group of the cysteine residue in position 110) is accessible to the reagents. After dissociation by 2 M NaCl, two SH-groups become titrable; however, the EPR spectra point to differences in the conformational state of these two groups. In 4 M urea, these differences are compensated for by structural disintegration. The spin labels may be used for the analysis of SH-groups under different conditions and at different functional states of nucleoproteins.
mesh_terms: D000818:Animals; D002417:Cattle; D003497:Cyclic N-Oxides; D003852:Deoxyribonucleoproteins / Q000032:analysis; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006657:Histones / Q000032:analysis*; D009589:Nitrogen Oxides; D013113:Spin Labels; D013438:Sulfhydryl Compounds / Q000032:analysis*; D013950:Thymus Gland / Q000032:analysis
chemical_list: D003497:Cyclic N-Oxides; D003852:Deoxyribonucleoproteins; D005609:Free Radicals; D006657:Histones; D009589:Nitrogen Oxides; D013113:Spin Labels; D013438:Sulfhydryl Compounds; C048774:2,2,6,6-tetramethyl-1-oxyl-delta(3)-piperidine-4-mercuribromide; C039900:nitroxyl
vernacular_title: Kharakteristika sul'fgidril'nykh grupp gistona H3 iz timusa telenka s pomoshch'iu rtut'soderzhashchikh nitroksil'nykh radikalov.