Practice question

Purification of DNA-dependent RNA synthesizing activity in Escherichia coli extracts was achieved independently by Samuel B. Weiss and Jerard Hurwitz around 1960, shortly after identification of messenger RNA concept. Using radiolabeled nucleoside triphosphates incorporation assays, they demonstrated enzyme requirement for double-stranded DNA template, four rNTPs, and magnesium, producing RNA-DNA hybrid product distinct from polynucleotide phosphorylase. Watson and Crick had elucidated DNA structure, Jacob and Monod operon regulation, Kornberg DNA polymerase. Weiss and Hurwitz discovery clarified enzyme responsible for operon transcription, foundational for understanding promoter specificity and sigma factor regulation in molecular biology history.