The kinetics of conformational changes of α2‐macroglobulin determined by time resolved X‐ray solution scattering

FEBS Letters

Arakawa, Hideo¹  Tsuruta, Hirotsugu⁴  Urisaka, Takuji¹  Ikaia, Atsushi¹  Kihara, Hiroshi³  Amemiya, Yoshiyuki² 

[1] Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama, Kanagawa 227, Japan;Photon Factory, National Laboratory for High Energy Physics, Tsukuba, Ibaraki 305, Japan;Jichi Medical School, School of Nursing, Minamikawachi, Tochigi 329-04, Japan;Biotechnology Division, Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, CA 94305, USA

关键词: α2-Macroglobulin;    X-ray solution scattering;    Time-resolved measurement;    Trapping mechanism;    α2M;    α2-macroglobulin;    R g radius of gyration;    PMSF;    phenylmethanesulfonyl fluoride;   

DOI  :  10.1016/0014-5793(94)80267-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The rate of gross conformational change of α₂-macroglobulin (α₂M) during its proteinase trapping was directly determined for the first time using time-resolved X-ray solution scattering. Decrease of radius of gyration was observed under pseudo-first-order conditions with excess proteinases, which exhibited a monophasic timecourse. The rate constants were 0.5 ± 0.1 s⁻¹ and 0.8 ± 0.2 s⁻¹ for the reaction with chymotrypsin and trypsin, respectively. There was no concentration dependence of the observed rate constants. Therefore, the rate-limiting step of the gross conformational change was not the bimolecular encounter reaction between α₂M and proteinases, which requires a new proposal of pre-trapping of proteinases before the gross conformational change.

【 授权许可】

Unknown