Reference : The pH dependence of rat liver RNA polymerases I and II.
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
The pH dependence of rat liver RNA polymerases I and II.
Bull, P. [ > > ]
Martial, Joseph mailto [Université de Liège - ULiège > Département des sciences de la vie > GIGA-R : Biologie et génétique moléculaire >]
Téllez, R. [ > > ]
Venegas, A. [ > > ]
Valenzuela, P. [ > > ]
Archivos de Biologia y Medicina Experimentales
Sociedad de Biologia de Chile
Yes (verified by ORBi)
[en] RNA polymerases ; pKa ; pH
[en] The effect of pH on the stability and activity of rat liver RNA polymerases I (A) and II (B) has been studied. Both enzymes are irreversibly inactivated in buffer solutions below pH 5.0. Km values of the two enzymes are constant between pH 6.5 and 8.7 but a two -to three- fold increase is observed between pH 8.7 and 9.7. The Vmax versus pH profiles are bell-shaped curves indicating the participation of two ionizing groups with apparent pKa values of 6.5 and 9.8 for enzyme I and 6.7 and 9.9 for enzyme II. Both enzymes are inactivated by photooxidation in the presence of Rose Bengal. It is suggested that the above pKa corresponds to the imidazole of a histidine residue and a amino group of a lysine residue.

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