DNA GYRASE FROM STREPTOMYCES-NOURSEI AND COMPARISON WITH GYRASES FROMOTHER SOURCES - GYR-B SUBUNIT MAY AFFECT THE PH-DEPENDENCE OF THE ENZYMATIC-ACTIVITY

Purified subunits of DNA gyrase from Streptomyces noursei have been ob tained with relatively high yield. By comparing the activity of the re constituted enzyme (supercoiling and cleavage reaction) with other gyr ase species and hybrid enzymes it is shown that the reactivity of gyra ses in vitro may differ significantly with pH, an effect not previousl y reported. The PH-effects on gyrase and hybrid enzyme activity seems to be largely determined by the Gyr B protein.