Paul-Soto R, Hernandez-Valladares M, Galleni M, Bauer R, Zeppezauer M, Frère J M, Adolph H W
Fachrichtung 12.4 Biochemie, Universität des Saarlandes, Saarbrücken, Germany.
FEBS Lett. 1998 Oct 30;438(1-2):137-40. doi: 10.1016/s0014-5793(98)01289-7.
The Bacteroides fragilis Zn-beta-lactamase is active with a mono- and a binuclear zinc site. The apoenzyme produced by removal of both Zn ions does not recover full activity upon readdition of Zn2+ in contrast to an active mono-Zn form prepared at pH 6.0. Differences in k(cat) values observed are substrate-dependent implying distinct mechanisms for the mono- and binuclear species. The substrate profile of a Zn,Cd hybrid obtained by selective exchange of one zinc ion is different from that of the Zn2 enzyme with a remarkable 15-fold increased activity with cefoxitin as substrate.
脆弱拟杆菌锌β-内酰胺酶在单核和双核锌位点均有活性。与在pH 6.0条件下制备的活性单锌形式不同，去除两个锌离子产生的脱辅基酶在重新添加Zn2+后不能恢复全部活性。观察到的催化常数（k(cat)）值差异取决于底物，这意味着单核和双核物种的机制不同。通过选择性交换一个锌离子获得的锌镉杂交体的底物谱与Zn2酶不同，以头孢西丁为底物时活性显著提高了15倍。
