Biologic molecules cytochrome

Kuznetsov studied Brdicka catalytic waves for several nonheme proteins and proposed that complete unfolding accompanied adsorption of these biological molecules. Cytochrome c gave rise to weak Brdicka currents, probably as a consequence of having only three hidden sulfur atoms per molecule. Senda et have recently stated that cytochrome c Brdicka... 

Once formed, the MV+ radical acts as a reducing agent and chemically reduces the redox centre of a biological molecule (illustrated here with the example of the electro-inactive enzyme, cytochrome-c), as follows ... 

Enzymatic hydroxylation of biological molecules is often catalyzed by hydroxylases. These types of enzymes are either oxygenases or peroxidases, in which the source of oxygen is O2 or H2O2, respectively. Cytochrome P-450-dependent enzymes represent a common class of enzymes that carry out hydroxylation reactions. L-Carnitine is a metabolite isolated from many organisms and its biosynthesis begins with the enzymatic hydroxylation of trimethyllysine. The intermediate, 3-hydroxyl-e-(A(A(ALtrimethyl)-L-lysine, is further... 

These are hemoproteins that catalyze electron transfer through the reversible change in oxidation state of the heme iron.637 They are involved in the respiratory chain, and in a wide range of other processes such as photosynthesis and the nitrogen cycle. Over 50 cytochromes have been studied, notably cytochrome c, which is one of the best studied biological molecules. Bacteria in particular produce a wide range of cytochromes which currently are attracting much attention. 

The NMR investigations involved studies of the spectra of ferro-cytochrom.es c, ferricytochromes c, and the complexes with cyanide ion. For the interpretation of the data it was particularly important that methionine is the only potential hemochrome-forming amino acid which contains a methyl group. Since some of the arguments used might also apply to NMR studies of metal-ion coordination in other biological molecules a rather detailed account of these experiments is presented. 

Perhaps the most important application of resonance Raman spectroscopy has been to the study ol biological molecules under physiologically significant conditions that is. in the presence of water and at low to moderate concentration levels.. - s an example, the technique has been useil lo determine the oxidation state and spin of iron atoms in hemoglobin and cytochrome c. In these molecules, the lesonance Raman bands are due solelv to ibrational modes of the tetra-... 

G. Del Re H-Bond Charge-Relay Chains in Multi-Heme Cytochromes and Other Biomolecules. In Spectroscopy of Biological Molecules (C. Sandorfy and T. Theophanides, eds.), pp. 15-37. Dordrecht Reidel (1984). 

The technique of optically transparent thin-layer electrochemistry (ottle) was first applied to the characterization of the stoichiometry and thermodynamics of horse heart cytochrome c by Heineman et alP This report showed how the special features of ottle can be combined with optical monitoring of a mediated biological electrode response to provide a simple, accurate, and precise means of characterizing the stoichiometry and thermodynamics of a biological molecule. The mechanism of mediation is described by the following equations ... 

A chronoamperometric method for evaluating the kinetics of homogeneous electron transfer between an electrochemically generated mediator/reactant and biological molecules was subsequently reported by Ryan et aiy The effects of solution ionic strength and the charge of the electrochemically generated reactant on the electron transfer kinetics with cytochrome c and cytochrome C2 were reported in that work. 

Several reports have evaluated the homogeneous electron transfer kinetics of cytochrome c using potential step spectroelectrochemistry. These reports together with other studies of biological homogeneous electron transfer reaction kinetics are summarized in Table 3. Evaluation of the kinetics of these reactions requires caution in that the small diffusion coefficients of the biological molecules studied relative to those of the electrochemically generated reactants mandates consideration of these parameters in data analysis. ... 

Reviews have appeared on the spectroelectrochemistry of biological molecules [104, 233]. Specialized reviews are also available on the direct electron transfer of cytochrome c [234] and potential inorganic redox reagents as mediators [235]. 

Dendrimers with porphyrin moieties at their centers have been investigated in some detail by Diederich and coworkers because of the similarity they have with biological molecules such as heme and cytochrome c [47-49]. Applications such as synthetic oxygen carriers for blood replacement can be envisioned for these materials. Also, a synthetic analog to cytochrome c could be utilized to transfer electrons in light-harvesting systems, albeit slightly different from the ones discussed previously. 

Thin-layer electrochemistry with an optically transparent electrode (OTE) enables simultaneous monitoring of both the electrochemical and optical responses of the system [1-3]. The oxidation state of the electroactive species in a cell can be precisely controlled by regulating the potential of the OTE and the species in the cell can be completely electrolysed within a short time (typically 20-120s). The electrochemical technique combined with a gold minigrid OTE was first applied to biological molecules to characterize the thermodynamic parameters of the redox reaction of horse heart cytochrome c in the presence of redox mediators [4]. 

The molar absorptivities of c-type cytochromes are determined by the coulometric titration with the OTTLE cell without the concentration of the biological molecule being known. 

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