We propose to collect diffraction data on four projects from our laboratory: ornithine decarboxylase (mODC) from mouse, biosynthetic arginine decarboxylase (bADC) from Escherichia coli (E. coli) , the truncated (yeast tE2) components of the pyruvate dehydrogenase complex from Sacchromyces cerevisiae , and the tE2 from the a-ketoglutarate dehydrogenase complex from E. Coli. Data collection of a select group of heavy metal derivatives for both mODC and bADC would aid in the structural determination of these two enzymes.