Structure of glycolate oxidase from spinach.

A high-resolution structure determination of glycolate oxidase from spinach is reported. X-ray data were collected on films at the synchrotron radiation source in Daresbury, England. The structure was solved by using two heavy-atom derivatives and a solvent-flattening procedure developed by B.-C. Wang. The subunit structure is essentially a structure of the eight-stranded alpha/beta-barrel type first described for triosephosphate isomerase. In addition, there are 70 residues at the NH(2) terminus and 45 residues between strand four and helix four of the barrel, which are arranged in a helical domain outside the COOH end of the parallel strands of the barrel. The active site is in a cleft between these domains with the coenzyme FMN essentially bound to the barrel and a substrate analogue, thioglycolate, bound to the helical domain. The molecule is octameric with 422 symmetry and has a 15- to 20-A-wide hole in the middle.