Search PubMed⌕ Search

Biomedical subjects

Y Ohba

Publications and source records attributed to Y Ohba.

At least 307 records · Page 17Linked to original sources
PubMed1979

Reaction of formaldehyde with calf-thymus nucleohistone.

The reactions of formaldehyde with calf thymus nucleohistone were analyzed in the following ways: measurement with fluorescamine of the decrease in primary amino groups resulting from hydroxymethylation and crosslinking reactions, measurement with dodecylsulphate-gel electrophoresis of formation of histone oligomers, measurement of fixation of histones to the DNA in nucleohistone, and measurement of changes in the circular dichroism spectrum in the region of 250--300 nm. In the presence of formaldehyde, the primary amino groups of histones decreased very rapidly, attaining an equilibrium within 60 min, and successively intermolecular crosslinks were also formed between histone molecules, the resulting dimers and oligomers being separable by dodecylsulfate-gel electrophoresis. Whereas the fixation reaction proceeded much more slowly. The extent of fixation could be measured more accurately by dodecylsulfate/sucrose centrifugation analysis than by sulfuric acid extraction. After removal of formaldehyde from the reaction mixture, the fraction of masked amino groups decreased, perhaps due to the reverse reaction, but the extent of fixation of histones continued to increase with time. No specificity was observed among five molecular species of histones in the fixation reaction. With increase in formaldehyde concentration, the ellipticity of nucleohistone decreased to a minimum with about 0.4% formaldehyde, and then increased.

Amino Acids↗
PubMed1977

Hemoglobin Pyrgos (beta83 Gly replaced by Asp) in a Japanese family.

A screening survey for abnormal hemoglobins at a hospital in Mizunami city, Gifu prefecture, Japan detected a fast-moving variant of hemoglobin in a family of Japanese origin. The abnormal hemoglobin constitutes about 45 percent of the total hemoglobin from the propositus and another carrier in the family, but neither of these persons had anemia, jaundice, cyanosis or splenomegaly. Structural analysis of this hemoglobin revealed that the amino acid substitution was at residue 83 in the beta chain, where a glycine was replaced by an aspartic acid. This hemoglobin variant has been previously reported in a Greek child (hemoglobin Pyrgos) (1). Oxygen affinity of hemoglobin Pyrgos was found to be normal.

Aged↗
PubMed1977

Hemoglobin Mizuho or beta 68 (E 12) leucine leads to proline, a new unstable variant associated with severe hemolytic anemia.

A hitherto undescribed, unstable hemoglobin was discovered in a four-year-old Japanese girl with relatively severe hemolytic anemia requiring monthly blood transfusion. Although no abnormal hemoglobin was detectable by electrophoresis at pH 8.6 and 7.0, heat denaturation and isopropanol tests gave positive results. Chemical analyses of the heat labile hemoglobin have demonstrated an amino acid substitution of a prolyl for the leucyl residue at the beta 68th (E 12) position. Remarkable clinical improvement was observed after splenectomy.

Amino Acid Sequence↗