Heme-heme orientation and electron transfer kinetic behavior of multisite oxidation-reduction enzymes

See allHide authors and affiliations

Science  25 Nov 1983:
Vol. 222, Issue 4626, pp. 929-931
DOI: 10.1126/science.6415814


Analysis of the polarized single-crystal absorption spectra of cytochrome cd1 of Pseudomonas aeruginosa shows that the heme c and heme d1 groups in each subunit are oriented perpendicularly to each other in both oxidized and reduced forms of the enzyme. These results, together with those of previous kinetic studies, indicate that a perpendicular heme-heme orientation may be an important factor in specifying kinetically slow steps in a sequential series of electron transfer reactions.