This is an application for a Conference Support Grant to support the Gordon Research Conference on the Chemistry and Biology of Pyrroles, which will be held on 23-28 July, 1990 at the Brewster Academy, Wolfeboro, New Hampshire. The Pyrroles GRC has been held biennially since 1972. The conference brings together a very diverse group of researchers who study aspects of chemistry and biology (both basic and health related) whose unifying feature is the involvement of pyrroles. Pyrroles have been called the "pigments of life" because they are essential elements in the molecules that carry out the universally important processes of respiration, electron transport, oxygen storage and transport, photosynthesis, and enzymatic oxidation reactions. Familiar pyrroles that have biological relevance include hemes, porphyrins, chlorophylls, bilins, and vitamin B12. Pyrroles are central to a number of human health areas. These include hereditary porphyrias (genetic defects in porphyrin biosynthesis), drug metabolism and steroid biosynthesis (which require cytochrome P-450), erythropoiesis (heme and hemoglobin synthesis), nutrition (vitamin B12), liver development (neonatal jaundice) and environmental toxicology (chemical-induced defects in pyrrole and pyrrole-dependent drug metabolism). Related areas that have contributed to the general understanding of pyrrole chemistry and biology include photosynthesis, microbial metabolism, oxidation-reduction and coordination chemistry, and micronutrient (metal) metabolism. The Pyrroles GRC is the only regularly held conference whose participants include both chemists and biologists having the wide and varied interests in the areas outlined above. Because of the breadth of coverage, the conference is considered by many of the participants to be the most important conference attended.