Escherichia coli TEM1 β‐lactamase in CTAB reverse micelles: exchange/diffusion‐limited catalysis

FEBS Letters

Moreno-Hagelsieb, Gabriel¹  Gómez-Puyou, Armando²  Soberon, Xavier¹ 

[1] Dpto. de Reconocimiento Molecular y Bioestructura, Instituto de Biotecnologı́a-UNAM, Av. Universidad 2001, Cuernavaca, Morelos 62210, Mexico;Instituto de Fisiologı́a Celular-UNAM, Apartado Postal 70242, Mexico City 04510, Mexico

关键词: Reverse micelle;    TEM1 β-lactamase;    Diffusion-limited catalysis;    Exchange-limited catalysis;    Bell-shaped activity;   

DOI  :  10.1016/S0014-5793(99)01228-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We report kinetic data of penicillin hydrolysis catalyzed by β-lactamase entrapped in reverse micelles formed with cetyl trimethylammonium bromide (CTAB), n-octane, hexanol and aqueous buffer. The K _cat of this diffusion-limited reaction can be improved in aqueous buffer by a factor of 1.1–1.2 just by increasing the phosphate buffer concentration from 50 to 100 mM. In reverse micelles, increasing the buffer concentration has little effect on K _cat when the size of the empty micelle is below the size of the protein. However, in larger micelles, the effect is enhanced and the K _cat improves several fold, changing the form of the curve of K _cat versus Wo from bell-shaped to almost hyperbolic. The results indicate that micellar exchange and internal diffusion may limit the reaction in reverse micelles and provide further evidence that the form of the curve depends on other factors besides the relationship between the size of the enzyme and that of the empty reverse micelle.

【 授权许可】

Unknown