The quantities of total and free guanine, adenine, hypoxanthine, and six of their methylated derivatives and of 6-succinoaminopurine have been measured in urine speci mens from cases of hepatocellular carcinoma and cirrhosis of the liver, and from normal subjects. Total base was defined as the sum of the free purine plus the increment released by means of acid hydrolysis. Analyses were per form...

Two cell lines, one proficient (Mex+) and one deficient (Mex-) in the ability to remove O6-methylguanine, have been isolated by Epstein-Barr virus-mediated transformation of a single blood sample obtained from a normal human male. Extracts of untreated cells differ in their O6-methylguanine transferase (methyl acceptor protein) activity. Although both lines arise from the same individual, they ...

Deamination of the oncogenic 1-methylguanine 3-oxide occurs to a significant extent in rats to yield 3-hydroxy-1-methylxanthine and its metabolites. When 3-hydroxy-1-methylxanthine is administered, 1-methyl-8-methylthioxanthine can be recovered from urine and released from hepatic protein. No 1-methyl-8-methylthioguanine was detected in urine or bound to protein. There is no evidence of signifi...

The density functional theory calculations of 7-methylguanine clusters revealed that stable ring assemblies can be formed with or without anions in the center position and hexameric clusters are the most stable and most planar ones. The coordination of anions (Cl⁻, Br⁻, NO₃⁻) stabilizes and thus favors the formation of planar aggregates. We believe that the predicted planar structures stabilize...

The quantities of total and free guanine, adenine, hypoxanthine, and six of their methylated derivatives and of 6-succinoaminopurine have been measured in urine speci mens from cases of hepatocellular carcinoma and cirrhosis of the liver, and from normal subjects. Total base was defined as the sum of the free purine plus the increment released by means of acid hydrolysis. Analyses were per form...

Two cell lines, one proficient (Mex+) and one deficient (Mex~) in the ability to remove 06-methylguanine, have been isolated by Epstein-Barr virus-mediated transformation of a single blood sample obtained from a normal human male. Extracts of un treated cells differ in their O6-methylguanine transferase (methyl acceptor protein) activity. Although both lines arise from the same individual, they...

A mechanism-based small molecular fluorescent probe has been developed to label active O(6)-methylguanine-DNA methyltransferase in live cells.

gene in human glioma cell lines. O-6-methylguanine DNA methyltransferase factors from and suppressed expression of the associated with exclusion of transcription Methylation-related chromatin structure is