Biophysical Society Thematic Meeting - November 16-20, 2015

Biophysics in the Understanding, Diagnosis, and Treatment of Infectious Diseases Poster Abstracts

18-POS Board 18 Substrate Specificity in the Amidases of Biomedical Importance – Insights from the Crystal Structures of a Model Bacterial Amidase S. W. Kimani , B T. Sewell. University of Cape Town, Cape Town, South Africa. S.W Kimani is the Wirsam Scholar Nitrilase superfamily amidases predominantly catalyze the conversion of amides to their corresponding acids and ammonia, with only a small subset performing the reverse amidase activity of condensation of non-peptidic amide bonds. These enzymes perform diverse but essential metabolic roles in vivo including detoxification of small molecules, protein post- translational modifications, protein degradation, and vitamin and co-enzyme biosynthesis, among others. Of importance are the medically-relevant amidases like the NAD+ synthetase and apolipoprotein N-acyltransferases from Mycobacterium tuberculosis and other pathogenic organisms, which play critical roles in NAD+ cofactor homeostasis and biosynthesis of mature membrane triacylated lipoproteins respectively, and have therefore been considered as potential targets for inhibitor design. Very little is however known about substrate specificity and catalysis in these enzymes. Using active site mutants of a model amidase from Nesterenkonia species, we have been able to understand how amidases recognize and bind amide substrates, as well as the contribution of the active site pocket size and geometry to substrate specificity and catalysis. Findings from this work will be presented. Dr Kimani’s participation has been made possible by WIRSAM SCIENTIFIC, agents for Rigaku.

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