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Yoshimasa Yoneyama: Influence Statistics

The rate of methemoglobin reduction by ascorbic acid was accelerated in the presence of ATP,2,3-diphosphoglycerate (2,3-DPG), and inositol hexaphosphate (IHP). The acceleration was as much as three times, four times, and ten times in the presence of ATP, 2.3-DPG, and IHP at pH 7.0, respectively. The changes of the concentrations of methemoglobin and ascorbic acid during the methemoglobin reduction were determined, and the reaction was found to proceed stoichiometrically in the presence ...

Reduced pyridine nucleotide dehydrogenase was purified 44,000-fold from normal human erythrocytes by procedures including ammonium sulfate fractionation, calcium phosphate gel chromatography, Sephadex G-100 gel filtration, and isoelectric focusing. The most purified enzyme preparation showed a single homogeneous peak (s 20,w = 2.77 S) upon ultracentrifugation and was nearly homogeneous on acrylamide gel disc electrophoresis. Absorption spectrum of the enzyme, fluorimetry of flavin, and ...

A NADPH-dehydrogenase of human erythrocytes was exhaustively purified to a homogeneous protein judging from the electrophoresis on a polyacrylamide gel in the presence of sodium dodecyl sulfate. Studies on the specificity for the electron acceptor of this enzyme suggest that flavins serve as the natural and direct electron acceptor. The enzyme showed a broad specificty for flavins and the Michaelis constants for flavins were estimated to be 5 × 10−5 M for both FMN and riboflavin. Rapid ...

The rates of O2 dissociation from hybrid-heme hemoglobin, in which one chain contains protoheme and the other chain meso- or deuteroheme, were measured at each heme site independently of changes at the partner chain site taking advantage of the differences in spectra between the two hemes in tetramers. The rates of O2 dissociation from hemoglobins and isolated chains containing unnatural hemes were also determined. The reaction corresponded to a first order process. The tetrameric ...

Two cytoplasmic cadmium-binding glycoproteins from the hepatopancreas of a whelk, Buccinum tenuissimum, were purified to homogeneity by Sephadex G-75 gel filtration and two DEAE-Sephadex A-25 chromatographies in the presence of 2-mercaptoethanol. These two cadmium-binding glycoproteins, termed FIIA and FIIB, each showed a single band after electrophoresis on 10% polyacrylamide gel at pH 8.9. The molecular weight of FIIA was estimated as 8000 and that of FIIB as 13000 by ...

Stable ferro-forms of hemoglobins containing various hemes such as dimethyl proto-, dimethyl meso-, etio-, meso-, hemato-, and deuteroheme were prepared by combination of human globin with hemes, followed by reduction with dithionite and purification with carboxymethyl Sephadex column. Sedimentation coefficients of these hemoglobins were all near to 4.0 S and chemical analysis showed that 4 moles of heme were bound per mole of hemoglobin. Esterification of propionyl carboxyl groups of ...

Two different methods were used to determine the number of Bohr protons released upon oxygenation of human hemoglobin (Hb A) and Hb A lacking beta 146 His (des-His Hb A) at the pH ranging from pH 5.0 to 9.0 in the presence of 0.1 M Cl- at 25 degrees C. One is the direct differential titration method, the other is based on the measurement of oxygen affinity as a function of pH. The results obtained for Hb A or des-His Hb A with two methods were completely mutually consistent. The number ...

Resonance Raman spectra of four hemoglobins (Hbs) M with tyrosinate ligand, that is, Hb M Saskatoon (beta distal His----Tyr), Hb M Hyde Park (beta proximal His----Tyr), Hb M Boston (alpha distal His----Tyr), and Hb M Iwate (alpha proximal His----Tyr), were investigated in order to elucidate structural origins for distinctly facile reducibility of the abnormal subunit of Hb M Saskatoon in comparison with other Hbs M. All of the Hbs M exhibited the fingerprint bands for the Fe-tyrosinate ...

Quantitative studies were made on the association of hemoglobin from the lamprey, Entosphenus japonicus, in a wide range of concentrations (0.01 to 3.4 mm) and pH values (5.6 to 8.0) with the aids of sedimentation equilibrium, sedimentation velocity, and diffusion measurements. Oxygen equilibrium was determined also in a wide range of concentrations by colorimetry and manometry. Molecular weights of the monomer and the largest aggregate were calculated to be 17,300 and 67,300, ...

Absorption and circular dichroism (CD) spectra of the Soret band, assigned as a pi-pi transition of the porphyrin pi-electron system, showed a great difference between alpha and beta subunits in the ferric state (alpha +, beta +). The nonequivalence of the spectra between alpha + and beta + subunits partly originates from the difference in the strength of the bond between heme iron and the proximal histidine. The peak positions for absorption and CD spectra of the ferric derivatives ...

Enzymatic reduction of the hemoglobin (Hb) M group was studied. Hb M Milwaukee-1 and Hb M Saskatoon were reduced by NADH-cytochrome b5 reductase highly purified from human erythrocytes. Hb M Saskatoon was also reduced by another enzyme in red cells, NADPH-flavin reductase. The reduction rates of Hb M Saskatoon by both enzymes were almost the same as those of MetHb A. The reduction of Hb M Milwaukee-1 by NADH-cytochrome b5 reductase progressed much more slowly than that of Hb M Saskatoon ...

The time course of methemoglobin reduction by ascorbic acid under anaerobic conditions was analyzed by using isoelectric focusing on Ampholine plate gel in order to compare results obtained by studies of the changes in absorption during the reaction. The intermediate hemoglobin which appeared all through the reaction was single and identified as the alpha3+beta2+ valency hybrid. In the presence of inositol hexaphosphate, reduction of methemoglobin was considerably accelerated and this ...

To clarify the role of the proximal histidine (F8-His), distal His (E7-His), and E11 valine (E11-Val) in ligand binding of hemoglobin (Hb), we have investigated the resonance Raman (RR) spectra of the carbon monoxide adduct of Hbs M (COHb M) in which one of these residues was genetically replaced by another amino acid in either the alpha or beta subunit. In the fully reduced state, all Hbs M gave v3 at approximately 1472 cm-1 and vFe-His at 214-218 cm-1, indicating that they have a ...

Hemoglobins (Hb) Yakima and Kempsey were purified from patients' blood with diethylaminoethyl cellulose column chromatography. The oxygen equilibrium curves of the two hemoglobins and the effects of organic phosphates on the function were investigated. In 0.1 M phosphate buffer, Hill's constants n for Hb Yakima and Hb Kempsey were 1.0 to 1.1 at the pH range for 6.5 to 8.0 and the oxygen affinities of both the mutant hemoglobins were about 15 to 20 times that of Hb A at pH 7.0. The Bohr ...