Document Detail


Evidence for the stereoselective inhibition of chick embryo hepatic ferrochelatase by N-alkylated porphyrins.
MedLine Citation:
PMID:  2811858     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
3,5-Diethoxycarbonyl-1,4-dihydro-2,6-dimethyl-4-ethylpyridine and its 4-propyl analogue were administered to phenobarbital-pretreated rats. The N-alkylprotoporphyrins (N-alkylPPs) that were isolated from rat livers, viz., N-ethylPP and N-propylPP, were found to have greater ferrochelatase-inhibitory potency than the corresponding synthetic N-alkylPPs. The N-ethylPP that was isolated from rat liver was found to contain 72% of the NB plus NA regioisomers, whereas synthetic N-ethylPP contained 40% of the NB plus NA regioisomers. In contrast, the N-propylPP that was isolated from rat liver contained the same amount of the NB/A regioisomer(s) as synthetic N-propylPP (33%). The NB plus NA regioisomers of N-ethylPP and the NB/A regioisomer(s) of N-propylPP that were isolated from rat liver were found to be significantly more potent than the corresponding synthetic regioisomers. We conclude that 1) the ferrochelatase-inhibitory potency of N-ethylPP that is isolated from rat liver is greater than that of synthetic N-ethylPP, due to differences in both regioisomer composition and the inhibitory potency of the NB plus NA regioisomers and stereoisomers, and 2) the ferrochelatase-inhibitory potency of N-propylPP that is isolated from rat liver is greater than that of synthetic N-propylPP, due solely to the difference in the ferrochelatase-inhibitory potency of the NB/A regioisomer(s) and stereoisomers. From the enhanced ferrochelatase-inhibitory potency of the NB plus NA regioisomers of N-ethylPP and the NB/A regioisomer(s) of N-propylPP that were isolated from rat liver, relative to the corresponding synthetic N-alkyllPP regioisomers, it was inferred that 2- and 4-vinyl substituents located on pyrrole rings A and B contribute to the optimal binding of N-alkylPPs to the ferrochelatase active site.
Authors:
S A McCluskey; R A Whitney; G S Marks
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular pharmacology     Volume:  36     ISSN:  0026-895X     ISO Abbreviation:  Mol. Pharmacol.     Publication Date:  1989 Oct 
Date Detail:
Created Date:  1989-11-24     Completed Date:  1989-11-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0035623     Medline TA:  Mol Pharmacol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  608-14     Citation Subset:  IM    
Affiliation:
Department of Pharmacology, Queen's University, Kingston, Ontario, Canada.
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MeSH Terms
Descriptor/Qualifier:
Alkylation
Animals
Chick Embryo
Chromatography, High Pressure Liquid
Circular Dichroism
Ferrochelatase / antagonists & inhibitors*
Liver / enzymology*
Lyases / antagonists & inhibitors*
Phenobarbital / pharmacology
Porphyrins / biosynthesis,  chemical synthesis,  pharmacology*
Stereoisomerism
Structure-Activity Relationship
Chemical
Reg. No./Substance:
0/Porphyrins; 50-06-6/Phenobarbital; EC 4.-/Lyases; EC 4.99.1.1/Ferrochelatase

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