The effect of <i>N</i>-methylprotoporphyrin IX on the synthesis of photosynthetic pigments in <i>Cyanidium caldarium</i>. Further evidence for the role of haem in the biosynthesis of plant bilins

Brown, Stanley B.; Holroyd, J. Andrew; Vernon, David I.; Troxler, Robert F.

doi:10.1042/bj2080487

Cited by 24 publications

(8 citation statements)

References 12 publications

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“…The inactivation observed for the R. sphaeroides enzyme is similar to that reported for the bovine ferrochelatase, although the kinetics vary slightly (Dailey et A feature common to all ferrochelatases examined to date, including the R. sphaeroides enzyme, is their extreme sensitivity to N-methylprotoporphyrin (1,4,8,11,18 patible with the hypothesis that N-methylprotoporphyrin is a tightly binding competitive inhibitor of the bacterial ferrochelatase (23).…”

Section: Discussionsupporting

confidence: 50%

Ferrochelatase from Rhodopseudomonas sphaeroides: substrate specificity and role of sulfhydryl and arginyl residues

Dailey¹,

Fleming²,

Harbin³

1986

J Bacteriol

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Purified ferrochelatase (protoheme ferrolyase; EC 4.99.1.1) from the bacterium Rhodopseudomonas sphaeroides was examined to determine the roles of cationic and sulfhydryl residues in substrate binding. Reaction of the enzyme sulfhydryl residues with N-ethylmaleimide or monobromobimane resulted in a rapid loss of enzyme activity. Ferrous iron, but not porphyrin substrate, had a protective effect against inactivation by these two reagents. Quantitation with 3H-labeled N-ethylmaleimide revealed that inactivation required one to two sulfhydryl groups to be modified. Modification of arginyl residues with either 2,3-butanedione or camphorquinone 10-sulfonate resulted in a loss of ferrochelatase activity. A kinetic analysis of the modified enzyme showed that the Km for ferrous iron was not altered but that the Km for the porphyrin substrate was increased. These data suggested that arginyl residues may be involved in porphyrin binding, possibly via charge pair interactions between the arginyl residue and the anionic porphyrin propionate side chain. Modification of lysyl residues had no effect on enzyme activity. We also examined the ability of bacterial ferrochelatase to use various 2,4-disubstituted porphyrins as substrates. We found that 2,4-bis-acetal-and 2,4-disulfonate deuteroporphyrins were effective substrates for the purified bacterial enzyme and that N-methylprotoporphyrin was an effective inhibitor of the enzyme. Our data for the ferrochelatase of R. sphaeroides are compared with previously published data for the eucaryotic enzyme.

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Section: Discussionsupporting

confidence: 50%

Ferrochelatase from Rhodopseudomonas sphaeroides: substrate specificity and role of sulfhydryl and arginyl residues

Dailey¹,

Fleming²,

Harbin³

1986

J Bacteriol

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“…Considerable progress has been made in our understanding of the biosynthesis of the phycocyanobilin chromophore from work with the unicellular red alga Cyanidium caldarium. In vivo studies demonstrated that both protoheme and biliverdin IXa could serve as precursors in the production of phycocyanobilin (10,(23)(24)(25)(26)188). In vitro studies with protein extracts from C. caldarium demonstrated the existence of activities that could convert heme to biliverdin IXa (10) and biliverdin IXa to phycocyanobilin (13).…”

Section: Chromophore Synthesismentioning

confidence: 99%

The phycobilisome, a light-harvesting complex responsive to environmental conditions.

Grossman

Schaefer

Chiang

et al. 1993

Microbiological Reviews

378

160

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“…5) which, up to this point, have been considered to be specific ferrochelatase inhibitors (10,11). Although these compounds have been reported to have no effect on Chl synthesis (and presumably Mg-chelatase) in vivo (2,6,19) (10).…”

Section: Regulation Of Mg-chelatase Activity By Greening and Putativementioning

confidence: 99%

Further Characterization of the Magnesium Chelatase in Isolated Developing Cucumber Chloroplasts

Walker¹,

Weinstein²

1991

Plant Physiol.

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Mg-chelatase catalyzes the first step unique to the chlorophyll branch of tetrapyrrole biosynthesis, namely the insertion of Mg into protoporphyrin IX (Proto). Mg-chelatase was assayed in intact chloroplasts from semi-green cucumber (Cucumis sativus, cv Sumter) cotyledons. In the presence of Proto and MgATP, enzyme activity was linear for 50 minutes. Plastid intactness was directly related to (and necessary for) Mg-chelatase activity. Uncouplers and ionophores did not inhibit Mg-chelatase in the presence of ATP. The nonhydrolyzable ATP analogs, O,-y-methylene ATP and adenylylimidodiphosphate, could not sustain Mg-chelatase activity alone and were inhibitory in the presence of ATP (lso 10 and 3 millimolar, respectively). Mg-chelatase was also inhibited by N-ethylmaleimide (l,o, 50 micromolar) and the metal ion chelators

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The effect of N-methylprotoporphyrin IX on the synthesis of photosynthetic pigments in Cyanidium caldarium. Further evidence for the role of haem in the biosynthesis of plant bilins

Cited by 24 publications

References 12 publications

Ferrochelatase from Rhodopseudomonas sphaeroides: substrate specificity and role of sulfhydryl and arginyl residues

Ferrochelatase from Rhodopseudomonas sphaeroides: substrate specificity and role of sulfhydryl and arginyl residues

The phycobilisome, a light-harvesting complex responsive to environmental conditions.

Further Characterization of the Magnesium Chelatase in Isolated Developing Cucumber Chloroplasts

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