2c3p: Difference between revisions

Pyruvate-ferredoxin oxidoreductases (PFOR) are unique among thiamine, pyrophosphate (ThDP)-containing enzymes in giving rise to a rather stable, cofactor-based free-radical species upon the decarboxylation of their, first substrate, pyruvate. We have obtained snapshots of unreacted and, partially reacted (probably as a tetrahedral intermediate) pyruvate-PFOR, complexes at different time intervals. We conclude that pyruvate, decarboxylation involves very limited substrate-to-product movements but a, significant displacement of the thiazolium moiety of ThDP. In this, respect, PFOR seems to differ substantially from other ThDP-containing, enzymes, such as transketolase and pyruvate decarboxylase. In addition, exposure of PFOR to oxygen in the presence of pyruvate results in, significant inhibition of catalytic activity, both in solution and in the, crystals. Examination of the crystal structure of inhibited PFOR suggests, that the loss of activity results from oxime formation at the 4' amino, substituent of the pyrimidine moiety of ThDP.

2C3P is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Desulfovibrio_africanus Desulfovibrio africanus] with MG, CA, SF4 and 1TP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Pyruvate_synthase Pyruvate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.2.7.1 1.2.7.1] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2C3P OCA].  

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