Combined microspectrophotometric and crystallographic examination of chemically reduced and X-ray radiation-reduced forms of cytochrome ba3 oxidase from Thermus thermophilus: structure of the reduced form of the enzyme.

ABSTRACT: Three paths for obtaining crystals of reduced (II-E4Q/I-K258R) cytochrome ba(3) are described, and the structures of these are reported at approximately 2.8-3.0 A resolution. Microspectrophotometry of single crystals of Thermus ba(3) oxidase at 100 K was used to show that crystals of the oxidized enzyme are reduced in an intense X-ray (beam line 7-1 at the Stanford Synchrotron Radiation Laboratory), being nearly complete in 1 min. The previously reported structures of ba(3) (Protein Data Bank entries 1EHK and 1XME ), having a crystallographically detectable water between the Cu(B) and Fe(a3) metals of the dinuclear center, actually represent the X-ray radiation-reduced enzyme. Dithionite-reduced crystals or crystals formed from dithionite-reduced enzyme revealed the absence of the above-me

SUBMITTER: Liu B 

PROVIDER: S-EPMC2638058 | biostudies-literature | 2009 Feb

REPOSITORIES: biostudies-literature