Bovine Phospholipase A2 Crystals Soaked in 30% Methanol: the First Structure Determination with a FAST Diffractometer at High Resolution

Data collection has always been a time-consuming operation in protein X-ray crystallography. This situation drastically changed with the introduction of two-dimensional area detectors. In this article the first successful refinement of a protein structure using data collected with an Enraf-Nonius Fast Area-Scanning TV-detector (FAST) diffractometer is reported. The test case was bovine pancreatic phospholipase A2 in a crystal form grown from 2-methyl-2,4-pentanediol and subsequently soaked in 30% v/v methanol containing buffer. The change in medium caused intensity changes without affecting the cell dimensions. The crystal structure of the 2-methyl-2,4-pentanediol form is known to high resolution. To elucidate the structural basis for the observed X-ray differences a data set to 1.75 Å, resolution was collected for the methanol-soaked crystals on the FAST diffractometer at a speed of 1700 reflections h-1. Refinement of the structure resulted in an R factor of 0.183, which proves the high quality of the diffraction data