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Biomedical subjects

S Miwa

Publications and source records attributed to S Miwa.

At least 451 records · Page 25Linked to original sources
PubMed1975

Binding of N-acetyl-chitotriose to human lysozyme.

The interaction of N-acetyl-chitotriose ((GlcNAc)3) with human lysozyme [EC 3.2.1.17] was studied at various pH values by measuring changes in the circular dichroic (CD) band at 294 or 255 nm and the data were compared with the results for hen and turkey lysozymes reported previously (Kuramitsu et al. (1974) J. Biochem.76, 671-683; Kuramitsu et al. (1975) J. Biochem. 77, 291-301). The pH dependence of the binding constant of (GlcNAc)3 to human lysozyme was different from those for hen and turkey lysozymes. The catalytic carboxyls of human lysozyme, Asp 52 and Glu 35, were not perturbed on binding of (GlcNAc)3. This is consistent with the previous findings that the macroscopic pK values of Asp 52 and Glu 35 of human lysozyme are 3.4 and 6.8 at 0.1 ionic strength and 25 degrees and were unchanged on complexing with (GlcNAc)3. An ionizable group with pK 4.5, which participates in the binding of (GlcNAc)3 to hen lysozyme and was assigned as Asp 101, did not participate in the binding of the saccharide to human lysozyme. Between pH 9 and 11, the binding constants of (GlcNAc)3 to hen lysozyme remained unchanged, whereas perturbation of an ionizable group with pK 10.5 to 10.0 was observed for human lysozyme. This group may be Tyr 62 in the active-site cleft. The binding constants of (GlcNAc)3 to human lysozyme molecules having different microscopic protonation forms, with respect to the catalytic carboxyls, were estimated using the binding constants obtained in the present experiments and the microscopic ionization constants of the catalytic carboxyls obtained previously. All four species of human lysozyme had similar binding constants to (GlcNAc)3. This result is different from those for hen and turkey lysozymes.

Acetylglucosamine↗
PubMed1975

Four new pyruvate kinase (PK) variants and a classical PK deficiency.

Four new red-cell pyruvate kinase (PK) variants are presented along with one case of so-called classical type PK deficiency. PK 'Tokyo II' had a low activity, Km (PEP) and Vmax, but a normal urea stability and only slight deviation from normal in neutralization tests by antiserum. It had a normal nucleotide specificity, abnormal electrophoretic mobility (fast moving) and the variant was associated with a mild hemolytic anaemia. PK 'Maebashi' had a low activity, high Km (PEP), low Vmax, urea instability, decreased reactivity to antiserum, normal electrophoretic mobility, normal nucleotide specificity and was associated with a moderate haemolytic anaemia. PK 'Tsukiji' had low activity, high Km (PEP), markedly high Vmax, urea instability, decreased reactivity to antiserum, abnormal electrophoretic mobility (fast moving) and grossly abnormal nucleotide specificity especially abnormal behaviour to ADP. The haemolytic process in this case was moderate to severe. PK 'Ube' was electrophoretically abnormal (fast moving) but otherwise had normal characteristics and the propositus was healthy and not anaemic. PK 'Ube' was found by electrophoretic screening for genetic PK polymorphism. In the classical type PK deficiency, the usual red-cell PK (PK-R1 and PK-R2) was not demonstrable by electrophoresis but instead M2-type PK was present, presumably by compensatory process. Kinetic studies confirmed that the patient's red-cell PK consisted of M2-type PK. This patient had a severe haemolytic anaemia.

Adult↗
PubMed1975

A new variant of erythrocyte pyruvate kinase - PK "maebashi".

A new case of erythrocyte pyruvate kinase deficiency was described. - A 9 year-old male patient was hospitalized because of anaemia, jaundice and splenomegaly. Diagnosis was made primarily on the basis of the erythrocyte enzyme studies. Because the pyruvate kinase of this patient demonstrated certain different characteristics from the other variants described previously, it was tentatively designated PK "Maebashi".

Adenine Nucleotides↗
PubMed1975

Electrophoretic, immunologic and kinetic characterization of erythrocyte pyruvate kinase in the Basenji dog with pyruvate kinase deficiency.

The electrophoretic mobility and the immunologic specificity of erythrocyte pyruvate kinase (PK) of the homozygous Basenji dog with PK deficiency were identical to those of normal M2-type PK isozyme seen in the white cell but not to those of the erythrocyte PK isozyme. Kinetic properties and stability were also consistent with the M2-type PK isozyme. Defective PK in the homozygous red cell was due to the absence of the erythrocyte PK isozyme and the compensatory presence of M2-type PK isozyme, as seen in the severe classical type PK deficiency in man.

Animals↗