Design of ruthenium-cytochrome c derivatives to measure electron transfer to cytochrome c peroxidase

Definition of the Interaction Domain for Cytochrome con Cytochrome c Oxidase

“…Ru-55-Cc was chosen because it is labeled with ruthenium trisbipyridine at lysine 55 on the bottom of Cc, remote from the binding domain, and should not significantly affect the interaction with CcO (see below). Laser flash photolysis of Ru-55-Cc resulted in rapid electron transfer from Ru(II*) to heme c Fe(III) with a rate constant of 4 ϫ 10 5 s Ϫ1 (26), as shown in Scheme I. The yield of heme c photoreduced by a single laser flash was approximately 2%.…”

Definition of the Interaction Domain for Cytochrome con Cytochrome c Oxidase

“…Ru-55-Cc was chosen because it is labeled with ruthenium trisbipyridine at lysine 55 on the bottom of Cc, remote from the binding domain, and should not significantly affect the interaction with CcO (see below). Laser flash photolysis of Ru-55-Cc resulted in rapid electron transfer from Ru(II*) to heme c Fe(III) with a rate constant of 4 ϫ 10 5 s Ϫ1 (26), as shown in Scheme I. The yield of heme c photoreduced by a single laser flash was approximately 2%.…”

Role of Configurational Gating in Intracomplex Electron Transfer from Cytochrome c to the Radical Cation in Cytochrome c Peroxidase

“…There is a concern that the ruthenium trisbipyridyl group might cause a change in the orientation of Ru-27-Cc at the binding site, raising the question of whether gating is a factor in the reaction of native horse Cc. Studies with a series of horse Ru-Cc derivatives labeled at lysines on the back surface of the protein indicate that the rate constant k eta for electron transfer to the Trp-191 radical cation by native horse Cc is approximately 10 5 s -1 (42). This value is more than 200-fold greater than the k et value of 5 × 10 2 s -1 predicted for the crystalline horse Cc-CcP complex using eq 4.…”

Synthesis and Physical Characterization of Novel Heme-Based Model Systems for Photoinitiated Electron Transfer. 2. Direct Ruthenation of Microperoxidase-11

“…All of these drawbacks are overcome or improved by the one-step approach used in the present study. A similar procedure was recently used for cytochrome c modification by Millett and co-workers and has proved to be quite versatile as a general method for protein amino group modification. Since only one of the methyl groups was transformed into a carboxyl group, the complications introduced by the free carboxyl group after modification are eliminated.…”

Definition of the Interaction Domain for Cytochrome con Cytochrome c Oxidase

“…Ru-55-Cc was chosen because it is labeled with ruthenium trisbipyridine at lysine 55 on the bottom of Cc, remote from the binding domain, and should not significantly affect the interaction with CcO (see below). Laser flash photolysis of Ru-55-Cc resulted in rapid electron transfer from Ru(II*) to heme c Fe(III) with a rate constant of 4 ϫ 10 5 s Ϫ1 (26), as shown in Scheme I. The yield of heme c photoreduced by a single laser flash was approximately 2%.…”

Role of Configurational Gating in Intracomplex Electron Transfer from Cytochrome c to the Radical Cation in Cytochrome c Peroxidase

“…There is a concern that the ruthenium trisbipyridyl group might cause a change in the orientation of Ru-27-Cc at the binding site, raising the question of whether gating is a factor in the reaction of native horse Cc. Studies with a series of horse Ru-Cc derivatives labeled at lysines on the back surface of the protein indicate that the rate constant k eta for electron transfer to the Trp-191 radical cation by native horse Cc is approximately 10 5 s -1 (42). This value is more than 200-fold greater than the k et value of 5 × 10 2 s -1 predicted for the crystalline horse Cc-CcP complex using eq 4.…”

Synthesis and Physical Characterization of Novel Heme-Based Model Systems for Photoinitiated Electron Transfer. 2. Direct Ruthenation of Microperoxidase-11

“…All of these drawbacks are overcome or improved by the one-step approach used in the present study. A similar procedure was recently used for cytochrome c modification by Millett and co-workers and has proved to be quite versatile as a general method for protein amino group modification. Since only one of the methyl groups was transformed into a carboxyl group, the complications introduced by the free carboxyl group after modification are eliminated.…”

Definition of the Interaction Domain for Cytochrome con Cytochrome c Oxidase

“…Ru-55-Cc was chosen because it is labeled with ruthenium trisbipyridine at lysine 55 on the bottom of Cc, remote from the binding domain, and should not significantly affect the interaction with CcO (see below). Laser flash photolysis of Ru-55-Cc resulted in rapid electron transfer from Ru(II*) to heme c Fe(III) with a rate constant of 4 ϫ 10 5 s Ϫ1 (26), as shown in Scheme I. The yield of heme c photoreduced by a single laser flash was approximately 2%.…”

Role of Configurational Gating in Intracomplex Electron Transfer from Cytochrome c to the Radical Cation in Cytochrome c Peroxidase

“…There is a concern that the ruthenium trisbipyridyl group might cause a change in the orientation of Ru-27-Cc at the binding site, raising the question of whether gating is a factor in the reaction of native horse Cc. Studies with a series of horse Ru-Cc derivatives labeled at lysines on the back surface of the protein indicate that the rate constant k eta for electron transfer to the Trp-191 radical cation by native horse Cc is approximately 10 5 s -1 (42). This value is more than 200-fold greater than the k et value of 5 × 10 2 s -1 predicted for the crystalline horse Cc-CcP complex using eq 4.…”

Synthesis and Physical Characterization of Novel Heme-Based Model Systems for Photoinitiated Electron Transfer. 2. Direct Ruthenation of Microperoxidase-11

“…All of these drawbacks are overcome or improved by the one-step approach used in the present study. A similar procedure was recently used for cytochrome c modification by Millett and co-workers and has proved to be quite versatile as a general method for protein amino group modification. Since only one of the methyl groups was transformed into a carboxyl group, the complications introduced by the free carboxyl group after modification are eliminated.…”