Abstract
1. 1. The reaction of nitric oxide with oxidized and reduced ascorbate oxidase ( l-ascorbate : oxygen oxidoreductase, EC 1.10.3.3) has been investigated by optical absorption measurements and electron paramagnetic resonance, and the results are compared with those of ceruloplasmin. 2. 2. Upon anaerobic incubation of oxidized ascorbate oxidase with nitric oxide a decrease of the absorbance at 610 nm is found, which is due to an electron transfer from nitric oxide to Type-1 copper. 3. 3. In the presence of nitric oxide the EPR absorbance of ascorbate oxidase decreases and shows predominantly a signal with characteristics of Type-2 copper ( g | = 2.248; A | = 188 G), whereas the Type-1 copper signal has vanished. 4. 4. Comparison of the intensities of the EPR signals before and after NO-treated points to the presence of one Type-2 and three Type-1 copper atoms per molecule of ascorbate oxidase. 5. 5. It is shown that the changes in the optical and the EPR spectrum of ascorbate oxidase induced by nitric oxide are reversible. No difference in enzymic activity is found between the native enzyme and the NO-treatment enzyme after removal of nitric oxide.
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.
