Carl W. Sigel

Reaction of biological thiols with the tumor inhibitor of jatrophone Inhibition of RNA polymerase

Abstract The plant-derived tumor inhibitor jatrophone has been shown to react with small molecular weight thiols as well as thio groups on proteins such as bovine serum albumin and RNA polymerase (nucleoside triphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) from Escherichia coli. In the latter case reaction with jatrophone was associated with loss of enzymatic activity. Thus after 11 SH groups per protomer of 400 000 daltons had reacted only approximately 10% of the activity remained. The substrates only partially protected the enzyme from loss of activity.