NONPLANAR PORPHYRINS AND THEIR SIGNIFICANCE IN PROTEINS

Nonplanar distortions of tetrapyrroles are prevalent in the hemes of h emoproteins, the pigments of photosynthetic proteins, and cofactor F-4 30 of methylreductase, The nonplanarity of these porphyrin cofactors i s currently believed to influence factors in the biological activity o f the proteins, in part, because the porphyrin deformations are often conserved within functional classes of proteins, The occurrence, class ification, and study of nonplanar porphyrins in proteins and synthetic nonplanar porphyrin analogs are reviewed.