Abstract
The iron-containing porphyrin heme is enzymatically synthesized by either one of three different routes: the protoporphyrin-, coproporphyrin- or siroheme-dependent pathway, named after the respective key intermediate. All three pathways rely on the action of Radical S-adenosylmethionine (SAM) enzymes at certain stages for the accomplishment of the most challenging chemical reactions. These are the oxidative decarboxylation of propionate groups under anaerobic conditions catalyzed by either coproporphyrinogen III dehydrogenase (CgdH, HemN) or coproheme dehydrogenase (ChdH, AhbD), and the removal of acetate groups, catalyzed by AhbC. Moreover, the biosynthesis of the dioxo-isobacteriochlorin heme d1 requires the removal of two propionate groups, which is accomplished by the Radical SAM enzyme NirJ, a close relative of AhbC. This review shortly summarizes the heme and heme d1 biosynthesis pathways and compares the structural, biochemical and mechanistic properties of the Radical SAM enzymes involved.
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 callMore From: Reference Module in Chemistry, Molecular Sciences and Chemical Engineering
Disclaimer: 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.
