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Biomedical subjects

M Tobe

Publications and source records attributed to M Tobe.

At least 91 records · Page 5Linked to original sources

Some evidence suggesting the existence of P2 and B3 sites in the active site of bovine pancreatic ribonuclease A.

In order to clarify the subsite structure of ribonuclease A (RNase A), the interactions of pdTp, pAp, dTpdAp, and pdTpdAp with RNase A were investigated by means of kinetic studies and 31P NMR spectroscopy. The pH profile of the 31P NMR spectrum of RNase A-pdTp complex indicated the interaction of the 3'- and 5'-phosphates with RNase A. The signal of 3'-phosphate of pdTp in the presence of RNase A gave a characteristic titration curve indicating the participation of more than 2 ionic groups in the P1 subsite. A similar 31P NMR titration was observed in the case of 5'-phosphate of pAp in the presence of RNase A. The results indicated that pAp interacted with RNase A at the P1, B2, and P2 sites. dTpdAp and pdTpdAp inhibited RNase A action more markedly than dTpdA, indicating the contribution of 3'- and 5'-terminal phosphate groups attached to dTpdA to the affinity of RNase A. The 31P NMR spectra of RNase A-dTpdAp and pdTpdAp complexes excluded the possible interaction of the monoester type phosphate of the inhibitors with the P1 site of RNase A, thus indicating the binding of the 3'-side phosphates with the P2 subsite of RNase A.

Animals↗

Effect of mitomycin C on bone marrow cells in mice.

The total and differential cell counts of femoral bone marrow and peripheral reticulocyte counts were determined in male ddY mice up to day 11 after an intraperitoneal injection of 2 mg/kg of mitomycin C. Total marrow cell counts showed a minimum value on day 2 after the injection, and then recovered to the control level on day 7. In the differential cell counts, the minimum values were observed on day 1 for proerythroblasts and basophilic erythroblasts, on day 2 for polychromatic erythroblasts, and on day 4 for mature neutrophils. Recovery was seen from the 4th to 7th days after injection. Marrow lymphocytes showed a maximum value when the total counts were minimum. The peripheral reticulocytes almost disappeared 4 days after the injection, and recovered to the pretreatment level on day 11.

Animals↗