Document Detail


Control of magnesium-protoporphyrin chelatase activity in Rhodopseudomonas spheroides. Role of light, oxygen, and electron and energy transfer.
MedLine Citation:
PMID:  4202754     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
1. Magnesium-protoporphyrin chelatase activity, previously shown in whole cells of Rhodopseudomonas spheroides, could not be demonstrated in cell-free extracts prepared in different ways, although spheroplasts retained moderate activity. Slight activity was detected also in whole cells of Rhodospirillum rubrum. 2. The effects on the activity of the enzyme of inhibitors of electron and energy transfer were studied in whole cells of Rps. spheroides. Amytal, rotenone, azide and cyanide inhibited at low pO(2) in the dark but not under anaerobic conditions in the light. Antimycin A and 2-heptyl-4-hydroxyquinoline N-oxide, as well as uncouplers and oligomycin, inhibited under all environmental conditions. 3. The effects on magnesium chelatase activity of intermediates of the tricarboxylic acid cycle, of thenoyltrifluoroacetone, of a number of artificial electron donors or acceptors, of various quinones and of the oxidation-reduction indicator dyes Benzyl Viologen and Methyl Viologen are described. 4. It was concluded that electron transport between a b-type and a c-type cytochrome as well as associated energy conservation and transformation reactions were essential for activity. There was also a specific requirement for ATP. 5. Exogenous protoporphyrin and magnesium protoporphyrin monomethyl ester were incorporated into bacteriochlorophyll or late precursors by whole cells. 6. Evidence is presented that the insertion of magnesium was the only step inhibited by oxygen in the biosynthetic pathway between protoporphyrin and bacteriochlorophyll.
Authors:
A Gorchein
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Biochemical journal     Volume:  134     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1973 Aug 
Date Detail:
Created Date:  1974-02-12     Completed Date:  1974-02-12     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  833-45     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Amobarbital / pharmacology
Antimycin A / pharmacology
Azides / pharmacology
Carbon Radioisotopes
Citric Acid Cycle
Cyanides / pharmacology
Cytochromes / metabolism
Electron Transport
Energy Transfer
Light*
Magnesium / metabolism*
Methionine / metabolism
Oligomycins / pharmacology
Oxidation-Reduction
Oxygen / metabolism,  pharmacology*
Rhodobacter sphaeroides / enzymology*
Rhodospirillum rubrum / enzymology
Rotenone / pharmacology
Chemical
Reg. No./Substance:
0/Azides; 0/Carbon Radioisotopes; 0/Cyanides; 0/Cytochromes; 0/Oligomycins; 57-43-2/Amobarbital; 63-68-3/Methionine; 642-15-9/Antimycin A; 7439-95-4/Magnesium; 7782-44-7/Oxygen; 83-79-4/Rotenone
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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