Arginine deiminase: Demonstration of two active sites and possible half-of-the-sites reactivity

Arginine deiminase (EC 3.5.3.6) from Mycoplasma arthritidis is a dimeric enzyme. Velocity centrifugation in 6 M guanidine HCl and peptide mapping of the BrCN fragments suggest that the subunits are identical. The reaction of one out of four sulfhydryl groups with 0.3 mM 5,5′-dithiobis-(2-nitrobenzoi...

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Veröffentlicht in:Biochemical and biophysical research communications 1978-07, Vol.83 (1), p.107-113
Hauptverfasser: Weickmann, Joachim L., Himmel, Michael E., Smith, Douglas W., Fahrney, David E.
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Sprache:eng
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Zusammenfassung:Arginine deiminase (EC 3.5.3.6) from Mycoplasma arthritidis is a dimeric enzyme. Velocity centrifugation in 6 M guanidine HCl and peptide mapping of the BrCN fragments suggest that the subunits are identical. The reaction of one out of four sulfhydryl groups with 0.3 mM 5,5′-dithiobis-(2-nitrobenzoic acid) has a half-life of about 30 min in 2 M guanidine HCl at 15°, pH 8. The enzyme is irreversibly inhibited by 1 mM formamidinium ion within 1 min. Inactivation by this affinity label is resolvable into two concurrent first-order reactions in the presence of guanidinium ion; the fraction of enzyme which reacts at the faster rate is about 50%. These results are interpreted as evidence for two catalytic subunits which differ in conformation.
ISSN:0006-291X
1090-2104
DOI:10.1016/0006-291X(78)90404-7