Properties of 5-Phosphoribosyl-1-pyrophosphate Amidotransferase from Human Lymphoblasts

Properties of 5-phosphoribosyl-1-pyrophosphate amidotransferase from human lymphoblasts.

The Inhibition of Phosphoribosyl-pyrophosphate Amidotransferase Activity by Cordycepin Monophosphate.

I. Cordycepin monophosphate has been shown to inhibit the activity of phosphoribosyl-pyrophosphate amidotransferase (ribosylamine-5-phosphate:pyrophosphate phosphoribosyltransferase (ghitamate-amidating), EC 2.4.2.14) obtained from both pigeon liver and Bacillus subtilis. 2. Evidence is presented for the existence of a phosphorylated derivative of cordycepin in Bacillus subtilis cells which wer...

Altered 5-phosphoribosyl 1-pyrophosphate amidotransferase activity in 6-thioguanine-resistant HL-60 human acute promyelocytic leukemia cells.

A novel mechanism of resistance to the antileukemic agent 6-thioguanine (TGua) was demonstrated in a clone (TGuo-30-2) derived from HL-60 human acute promyelocytic leukemia cells. The clone was isolated by prescreening mutagenized HL-60 cells in hypoxanthine-amethopterin-thymidine medium, followed by selection with 6-thioguanosine. TGuo-30-2 cells were cross-resistant to TGua and beta-2'-deoxyt...

Altered 5-Phosphoribosyl 1-Pyrophosphate Amidotransferase Activity in 6-Thioguanine-resistant HL-60 Human Acute Promyelocytic Leukemia Cells1

A novel mechanism of resistance to the antileukemic agent 6thioguanine (TGua) was demonstrated in a clone (TGuo-30-2) derived from HL-60 human acute promyelocytic leukemia cells. The clone was isolated by prescreening mutagenized HL-60 cells in hypoxanthine-amethopterin-thymidine medium, followed by selection with 6-thioguanosine. TGuo-30-2 cells were crossresistant to TGua and /8-2'-deoxythiog...

Purification and properties of phosphoribosyl pyrophosphate synthetase from rat liver.

Phosphoribosyl pyrophosphate synthetase has been purified extensively from rat liver. Gel filtration studies indicate that the enzyme is a complex of large molecular weight. On electron microscopy, stacking of enzyme molecules into long, linear aggregates is observed. The subunit molecular weight is 40,500, as measured by disc gel electrophoresis in sodium dodecyl sulfate. MgATP appears to be t...