P8 Isatin hydrolase: Diagnostics tool at atomic resolution
Isatin is a small aromatic compound found in a range of biological systems, e.g. in mammals as mono amine oxidase (MAO) inhibitor and in plants as a hormone. In mammals it has also been identified as a potential biomarker in Parkinsons disease1. We used isatin hydrolase, isolated from Labrenzia aggregata from in the Baltic sea, in a detection and quantification assay for isatin in biological samples. In this study we determined the crystal structure of isatin hydrolase to 1.4A resolution to understand the mechanism of enzyme reactivity. We also characterized the enzyme kinetics and thermodynamics. Isatin hydrolase is stable to 65 oC and binds manganese(II) with KD = 10 μM – app. 12 fold stronger than other common divalent metal ions. The enzyme structure revealed a dimeric enzyme with two domain swaps. A substrate recognition site and water entry channel to active site has also been identified. An inhibitor was identified and co-crystallized with the enzyme. Using the crystal structure isatin hydrolase can provide a scaffold for rational protein engineering toward new specificities. Schiff-bases of isatins forms a group of molecules with high pharmacological potential as e.g. cancer drugs.