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Biomedical subjects

F Tamanoi

Publications and source records attributed to F Tamanoi.

79 records · Page 5Linked to original sources
PubMed1978

Uracil incorporation into nascent DNA of thymine-requiring mutant of Bacillus subtilis 168.

A thymine-requiring mutant of Bacillus subtilis strain 168 accumulates short DNA chains after brief pulses with [(3)H]thymidine. Reversion of the thy mutation to thy(+) abolishes the accumulation of short DNA chains, suggesting that the accumulation is related to the thy mutation. The reason for this accumulation has been further investigated by analysis of a mutant with a defective uracil-DNA glycosidase activity (urg). The accumulation of short DNA chains in thy(-) cells is abolished by the deficiency of uracil-DNA glycosidase activity. In thy(+) cells, the deficiency of the glycosidase activity does not change the sedimentation profile of pulse-labeled DNA. DNA isolated from thy(-)urg(-) cells is fragmented by successive treatment with purified uracil-DNA glycosidase and alkali, indicating that uracil residues are present in this DNA. DNA isolated from thy(+)urg(-) cells is not fragmented by the same treatment. Significant radioactivity is detected in the dUMP region, when [(3)H]uridine-labeled DNA from thy(-)urg(-) cells is hydrolyzed and analyzed by thin-layer chromatography. Only a trace amount of radioactivity, which is not influenced by the deficiency of uracil-DNA glycosidase activity, is found in the dUMP region in DNA hydrolysates from thy(+) cells. These results suggest that, in thy(-) cells, uracil is incorporated into DNA and the accumulation of short DNA chains results from the excision-repair of this uracil whereas in thy(+) cells, uracil is seldom, if ever, incorporated into DNA.

Bacillus subtilis↗
PubMed1976

Synthesis of various phosphodiesters and phosphomonoesters with ribonuclease N.

1. 3'-Guanylyl-ethanol, 3'-guanylyl-propanol, and 3'-guanylyl-alpha-glycerol were synthesized by ribonuclease N1 [EC 3.1.4.8] using guanosine 2',3'-cyclic phosphate as a phosphate donor and various alcohols as phosphate acceptors. The yields of these phosphodiesters were 15%, 13.5%, 38.2%, respectively, with respect to phosphate donor under the optimum conditions. No phosphodiester was synthesized when 2-propanol was used as a phosphate acceptor. Thus, primary alcoholic hydroxyl groups may be regarded as the preferred phosphate acceptor. 2. 3'-Guanylyl-glucose and 3'-guanylyl-ribose were synthesized using glucose and ribose as phosphate acceptors. Under the optimum conditions, the yields of guanylyl-glucose amounted to 52.0%, while that of guanylyl-ribose was much lower. The guanylyl-glucose can be regarded as 3'-guanylyl-6-glucopyranose, based on the results of periodate oxidation. 3. Neither hydroxyamino acids (serine and threonine) nor N-acetylserinamide could be phosphorylated under the conditions used for the above phosphorylations. 4. 3'-Guanylyl-glycerol obtained as above was hydrolyzed by snake venon phosphodiesterase to produce glycerol 3-phosphate. The latter consisted of L-glycerol 3-phosphate (ca 17%) and the D-isomer (ca. 83%). Ribonuclease N1 thus catalyzes an asymmetric synthesis.

1-Propanol↗