Showing papers by "Emil F. Pai published in 2021"

Serial femtosecond and serial synchrotron crystallography can yield data of equivalent quality: A systematic comparison.

Abstract: For the two proteins myoglobin and fluoroacetate dehalogenase, we present a systematic comparison of crystallographic diffraction data collected by serial femtosecond (SFX) and serial synchrotron crystallography (SSX). To maximize comparability, we used the same batch of micron-sized crystals, the same sample delivery device, and the same data analysis software. Overall figures of merit indicate that the data of both radiation sources are of equivalent quality. For both proteins, reasonable data statistics can be obtained with approximately 5000 room-temperature diffraction images irrespective of the radiation source. The direct comparability of SSX and SFX data indicates that the quality of diffraction data obtained from these samples is linked to the properties of the crystals rather than to the radiation source. Therefore, for other systems with similar properties, time-resolved experiments can be conducted at the radiation source that best matches the desired time resolution.

Defluorination Capability of l-2-Haloacid Dehalogenases in the HAD-Like Hydrolase Superfamily Correlates with Active Site Compactness.

Abstract: l-2-Haloacid dehalogenases, industrially and environmentally important enzymes that catalyze cleavage of the carbon-halogen bond in S -2-halocarboxylic acids, were known to hydrolyze chlorinated, brominated and iodinated substrates but no activity towards fluorinated compounds had been reported. A screen for novel dehalogenase activities revealed four l-2-haloacid dehalogenases capable of defluorination. We now report crystal structures for two of these enzymes, Bpro0530 and Rha0230, as well as for the related proteins PA0810 and RSc1362, which hydrolyze chloroacetate but not fluoroacetate, all at ~2.2 A resolution. The active sites of these four enzymes are highly similar. In Molecular Dynamics (MD) calculations, only the defluorinating enzymes sample compacter conformations, which in turn allow more effective interactions with the small fluorine atom. Structural constraints, based on X-ray structures and MD calculations, correctly predict the defluorination activity of the homologous enzyme ST2570.

Signal transfer in human protein tyrosine phosphatase PTP1B from allosteric inhibitor P00058.

Abstract: Protein tyrosine phosphatases constitute a family of cytosolic and receptor-like signal transducing enzymes that catalyze the hydrolysis of phospho-tyrosine residues of phosphorylated proteins. PTP...