Rate of isomerization from closed to open complex (K2) of RNAP and A2 promoter

Value 0.04 sec^-1
Organism Bacteriophage T7
Reference McClure WR. Rate-limiting steps in RNA chain initiation. Proc Natl Acad Sci U S A. 1980 Oct77(10):5634-8. Table - link PubMed ID6160577
Method Promoter-specific lags in the approach to the steady-state rate of abortive initiation were observed when Escherichia coli RNA polymerase was added to initiate the reaction. The time required for a promoter and RNA polymerase to combine and isomerize into an RPO (RNA polymerase-promoter open complex) under a particular set of experimental conditions can be measured by initiating the promoter-specific abortive initiation reaction with RNA polymerase. The kinetic constants kon and k2 were evaluated from the slopes and intercepts of Fig. 2 (Tau observed vs 1/[RNAP], Tau observed is the average time required for open complex formation).
Comments The model of the reaction is R+P><RPc><RPo, where R is RNAP, P promoter, RPc RNAP-promoter closed complex, RPo RNAP-promoter open complex
Entered by Uri M
ID 105135