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Mechanism of action of 5-aminolaevulinate dehydratase from human erythrocytes.

ABSTRACT: Purified 5-aminolaevulinate dehydratase (porphobilinogen synthase, EC 4.2.1.24) from human erythrocytes was incubated initially with limiting amounts of 5-amino [5-14C]laevulinate in a rapid-mixing apparatus. The single-turnover reaction with respect to the bound labelled 5-aminolaevulinate was completed by the addition of unlabelled 5-aminolaevulinate and the resulting radioactive porphobilinogen was isolated and degraded. The 14C label was found to be located predominantly at C-2 of the product, demonstrating that, of the two substrate molecules participating in the reaction, the 5-aminolaevulinate molecule initially bound to the enzyme provides the propionic acid 'side' of the porphobilinogen. The same enzyme-[14C]substrate species that yields regiospecific porphobilinogen may be trapped by reaction with NaBH4, showing that the substrate molecule initially bound to the enzyme does so in the form of a Schiff base. A conventional incubation with 5-amino[5-14C]laevulinate yielded porphobilinogen with an equal distribution of the label between C-2 and C-11. The reaction mechanism of the human erythrocyte 5-aminolaevulinate dehydratase thus follows the same course as that of other dehydratases studied in our laboratory by using single-turnover techniques.

SUBMITTER: Jordan PM

PROVIDER: S-EPMC1144935 | biostudies-other | 1985 May

REPOSITORIES: biostudies-other

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Purification and properties of 5-aminolaevulinate dehydratase from human erythrocytes.

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Identification of lysine at the active site of human 5-aminolaevulinate dehydratase.

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In vitro anti-malarial efficacy of chalcones: cytotoxicity profile, mechanism of action and their effect on erythrocytes.

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Mechanism of methaemoglobin reduction by human erythrocytes.

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| S-EPMC1161898 | biostudies-other

Molecular mechanism for switching of P.falciparum invasion pathways into human erythrocytes

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2005-10-04 | GSE2878 | GEO

Investigation of the effect of metal ions on the reactivity of thiol groups in human 5-aminolaevulinate dehydratase.

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| S-EPMC5846730 | biostudies-literature

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