Abstract
Abstract Protoporphyrin monomethyl ester and protoheme monomethyl ester were recombined with apocytochrome c per-oxidase. The iron-free porphyrin-protein complex has absorption maxima at 408, 511, 547, 576, and 629 nm. The complex has no peroxidase activity. The protoheme monomethyl ester complex reacts with a stoichiometric amount of hydrogen peroxide to form a fairly stable peroxide intermediate (Compound ES) which exhibited an electron paramagnetic resonance (EPR) signal of a free radical type at g = 2.0. The EPR spectra of the synthetic enzymes containing protoheme mono- or dimethyl ester show that the enzymes were a mixture of high and low spin compounds at -196° similar to native enzyme. On careful observation, however, the EPR signal of the modified enzymes shows the presence of two different components with slightly different g values. The two components have similar properties in the reaction with cyanide and hydrogen peroxide and also in their electrophoretic and chromatographic patterns. The enzymic activity of the monoester enzyme in the peroxidation of yeast ferrocytochrome c was only 5.6% of that of the native enzyme. It was concluded that both of the propionic groups at positions 6 and 7 of the porphyrin ring are essential for the extremely high turnover rate of cytochrome c peroxidase.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
