title: The porphinedione structure of heme d1. Synthesis and spectral properties of model compounds of the prosthetic group of dissimilatory nitrite reductase.
abstract: In an attempt to verify the recent proposal that the heme d1 prosthetic group isolated from cytochrome cd1 is not a chlorin, but a dioxo-isobacteriochlorin (Chang, C. K. (1985) J. Biol. Chem. 260, 9520-9522), a model dioxo-isobacteriochlorin has been synthesized possessing a pi-electron system exactly identical to that as proposed. The presence of an acrylic acid substituent strongly perturbs the absorption spectrum of the chromophore and produces a visible spectrum virtually indistinguishable from that of the iron-free heme d1. Based on this finding, buttressed by additional spectral correspondence between the model iron heme and heme d1, we conclude that the proposed diketo ring structure is indeed correct, and the trivial names "dioneheme" and "acryloporphyrindione" are suggested for heme d1 and the demetallated macrocycle, respectively.
mesh_terms: D006418:Heme / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009572:Nitrite Reductases / Q000378:metabolism*; D013053:Spectrophotometry; D013329:Structure-Activity Relationship
chemical_list: D006418:Heme; C029400:heme d1; D009247:NADH, NADPH Oxidoreductases; D009572:Nitrite Reductases