Mutant cytochrome

Rapp-Giles BJ, Casalot L, English RS, et al. 2000. Cytochrome mutants of Desulfovibrio desulfuricans. Appl Environ Microbiol 66 671-7. 

Scheme 10.8 Biosynthesis of epothilone. Individual PKS domains are represented as circles and individual NRPS domains as hexagons. Acyl carrier proteins (ACPs) and thiola-tion domains (T) are posttranslationally modified by a phos-phopantetheinyl group to which the biosynthetic intermediates are covalently bound throughout the chain assembly. The thioesterase domain (TE) cyclizes the fully assembled carbon chain to give the 16-membered lactone. Following dehydration of Cl 2—Cl 3 to give epothilones C and D, the final step in epothilone biosynthesis is the epoxidation of the C12=C13 double bond by the cytochrome P450 enzyme P450epol<. KS ketosyn-thase KS(Y) active-site tyrosine mutant of KS AT acyltransfer-ase C condensation domain A adenylation domain ...

When the second-site revertants were segregated from the original mutations, the bci complexes carrying a single mutation in the linker region of the Rieske protein had steady-state activities of 70-100% of wild-type levels and cytochrome b reduction rates that were approximately half that of the wild type. In all these mutants, the redox potential of the Rieske cluster was increased by about 70 mV compared to the wild type (51). Since the mutations are in residues that are in the flexible linker, at least 27 A away from the cluster, it is extremely unlikely that any of the mutations would have a direct effect on the redox potential of the cluster that would be observed in the water-soluble fragments. However, the mutations in the flexible linker will affect the mobility of the Rieske protein. Therefore, the effect of the mutations described is due to the interaction between the positional state of the Rieske protein and its electrochemical properties (i.e., the redox potential of the cluster). 

Harder PA, DP O Keefe, JA Romesser, KJ Leto, CA Omer (1991) Isolation and characterization of Strepto-myces griseolus deletion mutants affected in cytochrome P-450-mediated herbicide metabolism. Mol Gen Genet 227 238-244. 

Ivancich, A., P. Dorlet et al. (2001). Multifrequency high-field EPR study of the tryptophanyl and tyrosyl radical intermediates in wild-type and the W191G mutant of cytochrome c peroxidase. J. Am. Chem. Soc. 123 5050-5058. 

Xu, J. Voth, G. A., Free energy profiles for H+ conduction in the D-pathway of Cytochrome c oxidase a study of the wild type and N98D mutant enzymes, Biochim. Bio-phys. Acta 2006,1757, 852-859. 

Haining RL, Hunter AP, Veronese ME, et al. Allelic variants of human cytochrome P450 2C9 baculovirus-mediated expression, purification, structural characterization, substrate stereoselectivity, and prochiral selectivity of the wild-type and I359L mutant forms. Arch Biochem Biophys 1996 333(2) 447 t58. 

Harlow, G.R. and Halpert, J.R. (1998) Analysis of human cytochrome P450 3A4 cooperativity construction and characterization of a site-directed mutant that displays hyperbolic steroid hydroxylation kinetics. Proceedings of the National Academy of Sciences of the United States of America, 95 (12), 6636-6641. 

Davydov, R., Makris, T.M., Kofman, V., Werst, D.E., Sligar, S.G. and Hoffman, B. M. (2001) Hydroxylation of camphor by reduced oxy-cytochrome P450cam mechanistic implications of EPR and ENDOR studies of catalytic intermediates in native and mutant enzymes. Journal of the American Chemical Society, 123, 1403-1415. 

The very weak coupling in Ru(His62)Zncyt c also could be accounted for by the 17-bond pathway that includes 3 H-bonds from His62 to the heme. Since the final H-bond in this case involves Trp59, we have designed a yeast cytochrome c mutant with a much shorter pathway that also is completed by the Trp59-heme propionate H-bond. The mutant has His in place of Leu at position 58. In our... 

In addition to the effect of mutations at Phe-82 on the stability of the cytochrome c active site, the intense, negative Soret Cotton effect in the circular dichroism spectrum of ferricytochrome c is profoundly affected by the presence of non-aromatic amino acid residues at this position [115]. Recent examination of six position-82 iso-l-ferricytochrome c mutants establishes that while Tyr-82 exhibits a Soret CD spectrum closely similar to that of the wild-type protein, the intensity of the negative Soret Cotton affect varies with the identity of the residue at this position in the order Phe > Tyr > Gly > Ser = Ala > Leu > He, though the Ser, Ala, He, and Leu variants have effectively no negative Soret Cotton effect [108]. 

Steady state kinetics and protein-protein binding measurements have also been reported for the interaction of these mutant cytochromes with bovine heart cytochrome c oxidase [120]. The binding of cytochrome c variants to the oxidase occurred with increasing values of Kj in the order He (3 x 10 Mol L ) < Leu = Gly < wild-type < Tyr < Ser (3 x 10 molL ). Steady-state kinetic analysis indicated that the rate of electron transfer with cytochrome c oxidase increased in the order Ser < He < Gly < Leu < Tyr < wild-type, an order notably different from that observed for a related analysis of the oxidation of these mutants by cytochrome c peroxidase [85]. This difference in order of mutant turnover by the oxidase and peroxidase may arise from differences in the mode of interaction of the cytochrome with these two enzymes. 

The non-congruence of the values for interaction of the mutants with cytochrome c oxidase with the K , values calculated from the steady-state kinetic analysis included in this study suggests that the rate of cytochrome c oxidation by the oxidase is not limited by the rate of product dissociation. 

Fig. 2a-c. Stereodiagram of the yeast iso-1-cytochrome c surface, (a) Surface of the wild-type protein (b) surface of the Ser-82 mutant (c) surface of the Gly-82 mutant. (Modified from Refs. [123, 124])... 

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