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Lactose Operator–Repressor Interaction* *This is paper 8 in our series, "Studies on the Lactose Operon." Paper 7 is Bahl et at. (6).

1978; Academic Press; Linguagem: Inglês

10.1016/b978-0-12-152813-3.50009-4

0070-2137

Ray Wü, Chander P. Bahl, Saran A. Narang,

DNA and Nucleic Acid Chemistry

This chapter discusses the lactose operator–repressor interaction. Any method for quantitatively studying the operator–repressor interaction requires either the operator or the repressor species to be labeled. After the interaction has taken place, the method must be able to separate the unreacted labeled material from the bound, labeled material. Two different methods have been used to study the operator–repressor interaction. Gilbert and Muller-Hill used 35S-labeled lac repressor. The operator–repressor complex was separated from the unreacted lac repressor by zonal centrifugation on a 5–30% glycerol gradient. The method requiring labeled operator DNA is the one most commonly used. A convenient and accurate method has been developed and extensively used by Riggs and Bourgeois for studying various properties of the operator–repressor complex. In this method, the DNA–protein complex is separated from the unbound labeled DNA by passing the reaction mixture through a nitrocellulose membrane filter. The DNA–protein complex is retained on the filter, whereas the unbound DNA passes through. The chapter also discusses the lac operator interaction with a wild-type repressor.