Alvin Segal, Margaret Schroeder, Philip Barnett, and Bernard L. Van Duuren.
Studies of the Effects in vitro of Beta-Propiolactone and Beta-Propiolact[14C]one on Whole Mouse Skin Chromatin.
Biochemical Pharmacology 23:937- 946, (1974).
Abstract
Whole mouse skin chromatin was reacted with Beta-propiolactone (BPL) in vitro. The alkylated chromatin preparation was isolated essentially intact. The transition midpoint (Tm) of the alkylated chromatin preparation was reduced by 24°, its template activity for RNA synthesis was virtually abolished, its chromosomal RNA (cRNA) content was reduced and lysine-rich histones F1 and 1° could no longer be detected on polyacrylamide gels. DNA from this alkylated chromatin showed a similar decrease in Tm and template activity. The histones in alkylated chromatin stabilized DNA against heat denaturation to a similar extent compared to untreated chromatin. Mouse skin DNA alkylated with BPL had properties similar to those of DNA from alkylated chromatin. Buoyant density studies revealed that DNA isolated from alkylated chromatin exhibited peaks corresponding to alkylated and normal DNA. Mouse skin DNA alkylated under identical conditions exhibited a single peak of alkylated DNA. Thus portions of DNA in mouse skin chromatin appeared to be protected against alkylation in vitro with BPL. This was confirmed in studies using Beta-propiolact[14C]one (BPL-14C]). The alkylation reactions were repeated using reduced quantities of BPL-14C. DNA isolated from BPL-14C-alkylated whole mouse skin chromatin contained 29 per cent of the bound radioactivity found in louse liver DNA alkylated under identical conditions. Acidic proteins and histones as well as DNA were shown to bind BPL-14C. Among the histone classes, F1 and 1° contained the greatest amount of bound BPL-14C.