Friday, May 31, 2019
causes of life :: essays research papers
For biologists, x-ray crystallography has al shipway been a tricky technology. Harder than getting a good beam was growing large crystals of biological molecules-a task thats been comp ard to building weak structures from wiggly bits of Jello. Today, synchrotron light from facilities such as Berkeley Labs Advanced Light Source may make it possible to use protein crystals as small as 50 microns (50 millionths of a meter) in length. The crystals themselves may also become easier to grow, thanks to a unique robotic system designed and built by Joseph Jaklevic, head of Engineering Sciences, and his colleagues in the Engineering Divisions Bioinstrumentation Department. "The idea for a high-throughput combinatorial approach to crystal growth came from Peter Schultz," says Jaklevic. "The basic idea is that, instead of having to plod through all the hundreds of ways you might get a protein to crystallize, you more or less try em all at once." Schultz pioneered combinatorial methods as a element of the Labs Materials Sciences Division he recently became head of the Novartis Institute for Functional Genomics in La Jolla, California. He and his colleague Raymond Stevens of the Labs Physical Biosciences Division saw the combinatorial approach as a natural solution to the challenge of growing protein crystals. Thats because "biologists really have no idea what the best conditions are for growing crystals of a new protein," says Derek Yegian, a member of the team that built the new robotic system. "Different proteins precipitate out of solution and grow at opposite rates-or dont grow at all-depending on the solutions acidity, temperature, concentrations of salts, and lots of separate variables. " The innovative robot above, designed and built by Joe Jaklevic and his colleagues in the Engineering Divisions Bioinstrumentation Department, can automatically grow crystals of a novel protein by screening 480 different growth solutions at once. Only the very purest proteins will crystallize, and pure protein is expensive even common commercial proteins can cost hundreds of dollars a gram. Often hundreds of combinations of variables must(prenominal) be tried before a novel protein can be crystallized from solution. Most trial solutions are prepared by hand at the rate of about 30 an hour, typically requiring one to 10 microliters of pure protein for 50 to 100 "coarse-screening" trials whether a particular solution yields a crystal is unembellished only days or weeks later. "Manual methods are slow and error-prone," says Yegian, and although some steps have been automated within the past few years, "commercial robots are not much better.