An EPR study of the interactions between heme and flavin in yeast flavocytochrome b2

Abstract

E.P.R. experiments and spin-lattice relaxation time measurements have been performed on Flavocytochrome b2 in the range 10 K to 100 K, to obtain information on the distance between the two prosthetic groups of the protein, flavin and heme. We have used the stabilization effect of pyruvate on the semiquinone form of the flavin, to compare the E.P.R. spectral shape and the relaxation properties of the radical when the heme is either in the ferrous form or in the ferric form. When the heme is ferric, no significant increase of the line broadening or enhancement of the relaxation rate of the radical can be detected in the range 10 K to 100 K. From these results, a minimum intercentre distance of 18 to 20 A can be estimated.

Temperature-Jump and Potentiometric Studies on Recombinant Wild Type and Y143F and Y254F Mutants ofSaccharomyces cerevisiaeFlavocytochromeb2: Role of the Driving Force in Intramolecular Electron Transfer Kinetics,

“…Given the previously quoted values of T ab and λ, J can be predicted to be in the 3 × 10 -9 to 8 × 10 -7 cm -1 range. Such small values are consistent with the fact that no effects attributable to the exchange interactions have been observed on the EPR spectrum (60). The fact that no dipolar effects are observed either has been previously discussed elsewhere (52).…”

Flavocytochrome b2-Mediated Electroactive Nanoparticles for Developing Amperometric L-Lactate Biosensors

“…Is the electroactivity of the best NPs perhaps the only cause of such an effect? Unfortunately, the detailed mechanisms of heme-containing Fc b 2 activity are still unknown [ 25 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. Additionally, the structures and kinetic characteristics of Fc b 2 from the yeasts S. cerevisiae and H. anomala have some differences [ 55 , 56 , 57 ], and the structure of Fc b 2 from the yeast O. polymorpha is not yet reported.…”