Greatly reduced radiation damage in ribonuclease crystals mounted on glass fibers

X-ray data have been collected from crystals of bovine pancreatic ribonuclease A at temperatures of 220K and below, by use of a nitrogen-gas cold stream and a computer-controlled diffractometer. One data set, collected from a crystal mounted in the traditional manner in a quartz capillary tube, showed radiation damage of 21% after 14.6 days of exposure to Cu Kα radiation at 160K. Another crystal, mounted on a glass fiber by use of uncured epoxy cement, showed only a 3% decay of the intensity standards after 28.3 days of exposure to the same radiation and at similar temperatures.