Student Abstracts: Chemistry at SLAC

Construction of a Protein Crystallographic Calculator. PREETI SHANBHAG (Bethune-Cookman College, Holly Hill, FL 32117) ANA GONZALEZ (Stanford Linear Accelerator Center, Stanford, CA 94025) .
The architecture of macromolecules can be determined by the diffraction of x-rays over the protein crystals. Crystals have a very high degree of internal order, and are composed of repeating groups of the same arrangements of atoms and molecules, which are called cells. After obtaining a perfect crystal, its reflection, which is arranged in a precise diffraction pattern is obtained by directing an X-ray beam onto a crystal. The intensity corresponds to the reflection of the X-rays, and has a characteristic interplanar spacing 'd'. The 'd' is related to the angle of the X-ray scattering, , by Bragg's law. The Bragg's equation is: n = 2d sin , where  is the wavelength of the radiation. Using this information, a program has been created that will calculate the maximun and minimum resolution, as well as the maximum cell dimension and wavelength. This program is written in Tcl/Tk (Tool Command Language, with it's graphical counterpart, Toolkit).