The 1.6 angstrom resolution crystal structure of a mutant plastocyanin bearing a 21-25 engineered disulfide bridge

Plastocyanin is an electron-transfer protein which has been largely used fo r biophysical studies as well as for protein-engineering experiments. A sur face disulfide bridge has been engineered in poplar plastocyanin to allow p rotein chemisorption on gold substrates. The mutated plastocyanin crystal s tructure has been studied at 1.6 Angstrom resolution (R factor = 0.145, R-f ree = 0.205) to characterize the effects of the engineered disulfide on the overall protein structure and on the Cu-coordination sphere in view of bio physical applications. The new orthorhombic crystal form isolated for the m utated plastocyanin displays two protein molecules per asymmetric unit.