Biomedical subjects

Y Enoki

Publications and source records attributed to Y Enoki.

At least 73 records · Page 4Linked to original sources

PubMed1982

Trypsin-catalyzed synthesis of peptide bond in human hemoglobin. Oxygen binding characteristics of Gly-NH2(142 alpha) Hb.

Incubation of human hemoglobin (Hb) A with glycineamide (Gly-NH2) in the presence of trypsin gives rise to two bands of approximately equal amount on the isoelectric focusing gel. Structural analyses, including digestion with trypsin and carboxypeptidases A and B, have shown that one is unmodified Hb A and the other is Gly-NH2(142 alpha) Hb in which Gly-NH2 is bound to the COOH-terminal residue of the alpha subunit (Arg 141 alpha) via peptide bond. Gly-NH2(142 alpha) Hb exhibits slightly increased affinity for oxygen and slightly reduced heme-heme interaction as compared with normal Hb A. Although Gly-NH2(142 alpha) Hb exhibits normal 2,3-diphosphoglycerate effect, the alkaline Bohr effect and chloride effect are diminished. These oxygen binding properties are attributable to abolished binding of chloride to the anion binding site positioned between the alpha-amino group of Val 1 alpha and the guanidinium group of Arg 141 alpha. Gly-NH2(142 alpha) Hb restores normal oxygen binding properties upon trypsin digestion which removes Gly-NH2 from the COOH terminus of the alpha subunit.

Adult↗

PubMed1982

Characterization of quantitation of glycosylated hemoglobins in canine blood.

Canine hemolysates exhibited two minor and one major hemoglobins when chromatographed on Bio Rex-70 column with 0.05 M phosphate-0.01 M KCN (pH 6.5) containing 0.015 M NaCl. The first minor fraction was electrophoretically heterogeneous, constituting at least two hemoglobins. The second was completely homogeneous with somewhat faster anodal mobility than the major one and the difference was shown to be localized solely in the beta subunits. Thiobarbituric acid reaction was strongly positive for this hemoglobin, indicating the presence of glycosyl ketoamine linkage. We describe a simple and reliable procedure for quantitation of the canine glycosylated hemoglobins with a home-made Bio Rex-70 mini-column.

Animals↗

PubMed1980

Influence of quaternary structure on the state of the haem in carp and human methaemoglobins studied by resonance Raman scattering.

the resonance Raman spectra of carp and human methaemoglobin (metHb) derivatives in the T and R quaternary structures were measured in the frequency regions of 1200-1700 cm-1 and 100-600 cm-1. Conversion of carp and human fluoro metHb's to the T structure was accompanied by a frequency shift of the Raman line at 348 cm-1 to lower frequency by 5 cm-1, but all other lines were unaffected by the R-T transition. As the 348 cm-1 line was assigned to a porphyrin mode (v8) involving a bending motion of peripheral groups, the frequency change may be attributable to a change in van der Waals' interaction between haem and globin. On addition of inositol hexaphosphate to carp azide metHb, the intensity ratios of Raman lines (cm-1/cm-1), 1588/1567, 1641/1606, and 349/377, decreased. This indicates a shift of the high-spin/low-spin equilibrium towards high-spin side, in agreement with the rise in magnetic susceptibility. No distinct change was detected for the Raman spectra of aquo and cyano met Hb's on the R-T transition, even in the lower frequency region.

Animals↗

PubMed1980

Functional properties of the glycosylated minor hemoglobins A1a-1,A1a-2 and A1b. EPR evidence for increased stability of the low affinity quaternary structure and decreased susceptibility to organic phosphate.

Electron paramagnetic resonance (EPR) spectra of the glycosylated minor hemoglobins A1a-1, A1a-2, A1b and A1c and the major hemoglobin A0 in the nitrosyl form have been obtained in the absence and presence of inositol hexaphosphate. In the absence of inositol hexaphosphate, nitrosyl hemoglobins A1a-1, A1a-2 and A1b exhibited a triplet hyperfine structure centered at g = 2.009 which has been shown to be diagnostic of the low affinity (T) quaternary structure. Addition of inositol hexaphosphate to nitrosyl hemoglobins A0, A1c, A1b and A1a-2 developed a triplet hyperfine structure of the EPR spectra but the magnitude of the hyperfine was decreased in the order of hemoglobins A0, A1c, A1b and A1a-2. However, inositol hexaphosphate had essentially no effect on the EPR spectrum of nitrosyl hemoglobin A1a-1. The present results account qualitatively for the oxygen binding properties of these glycosylated minor hemoglobins in the framework of a two-state allosteric model.

Allosteric Regulation↗

PubMed1979

Earthworm (Pheretima communissima and Pheretima hilgendorfi) hemoglobins: giant assemblies and subunits.

The molecular architecture of hemoglobins and their subunits of the earthworms Pheretima communissima and Pheretima hilgendorfi was investigated. In both species, their s0.20,w of 60.8 S and D020,w of 1.80 . 10(-7) cm2 . s-1 corresponded to a molecular weight of 3.07 . 10(6). From electron microscopic observations, the overall structure of the hemoglobins was shown to be two superimposed hexagonal discs, each composed of six-membered constituents. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of both hemoglobins revealed the presence of five species of subunits with molecular weights of 13,000-14,000 (subunit 1), 27,000-28,000 (subunit 2), 30,000-31,000 (subunit 3), 33,000-34,000 (subunit 4) and approx. 52,000 (subunit 5), respectively, and the molar ratio of these subunits 1:2, 3, 4:5 was 2:3:3. If we consider this set of the subunits 1 to 5 as one unit, the molecular weight of this unit should be 2.7-2.8 . 10(5). This one unit, therefore, should be considered to represent one-twelfth the whole molecule with molecular weight of 3.07 . 10(6).

Animals↗

PubMed1976

The dissociation of human deoxyhemoglobin and mixed state hemoglobin into monomer.

The experimental hybridizations between fully deoxygenated human and canine hemoglobins and between half-ligated human hemoglobin and canine cyanomethemoglobin show that new two hybrids in addition to the parent hemoglobins were clearly formed in the mixtures at the high concentration of KI. Thus, human deoxyhemoglobin under the present conditions is in an equilibrium with three species, tetramer in equilibrium dimer in equilibrium monomer. This means that the deoxyhemoglobin is in R-T equilibrium, and shifts considerably toward the R state under the present conditions. On the other hand, the half-ligated hemoglobin in 1.5 M KI becomes much more dissociable than the deoxy T state and appears to be completely transformed into the R state. Nevertheless, the co-operativity, n, is still high (n = 2.0).

Animals↗

PubMed1976

Oxygenation properties and intraerythrocytic constituents of human blood when stored in different media of ACD and CPD.

In the blood stored in acid-citrate-dextrose solution (ACD blood), the oxygen affinity and red cell 2, 3-diphosphoglycerate (2, 3-DPG) content showed parallel exponential decays with half-lives of 3 to 4 days. In the blood stored in citrate-phosphate-dextrose solution (CPD blood), the two parameters increased during the first 4 days before showing the same decay as that seen in the ACD blood. There was no significant change in the transmembrane pH gradient of the red cells, and thus the intracellular pH at the plasma pH of 7.40 was always in the range of 7.17 +/- 0.02 throughout the period of storage in ACD medium. In both ACD and CPD blood, the Hill exponent n was always normal (approximately 2.8) while the Bohr coefficient (delta log P50/delta pH) rose along with the lapse of time for preservation. The oxygen affinity of the CPD blood was less influenced by the red cell 2, 3-DPG than was that of the ACD blood. This phenomenon was thought to derive from higher concentration of salts within the CPD-stored red cells. The efficiency of blood oxygen transport in ACD and CPD blood was compared.

Blood Preservation↗

PubMed1975