AN APPLICATION OF GENETIC ENGINEERING FOR SOLVING THE CRYSTAL STRUCTURE OF TAQ DNA POLYMERASE. Youngsoo Kim, The Yeungnam University, Kyungsan, South Korea 712-749

Taq DNA polymerase from Thermus aquaticus has been shown to be very useful in the polymerase chain reaction method, which is being used for amplifying DNA. Not only is Taq DNA polymerase highly useful in commercial value for the polymerase chain reaction application, but it is also important in studying DNA replication because it is apparently an homologue to E. coli DNA polymerase I which has long been used for DNA replication study (Lawyer et al., 1993). The crystal structure of Taq DNA polymerase could be useful as a substitute for DNA replication study of E. coli DNA polymerase I. The structure determination of Taq DNA polymerase was initiated. The crystals of intact Taq DNA polymerase were grown at 22deg.C by the hanging drop method. X- ray diffraction pattern breaks down a crystal structure into discrete sine waves in Fourier series. The original shape of an object in the form of electron density may be represented as the sum of those sine waves with varying amplitudes and phases in three dimensions. The molecular replacement is sometimes utilized to provide phase information. This report will describe phase determination to solve the crystal structure of Taq DNA polymerase by the molecular replacement.