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Biomedical subjects

D Dolphin

Publications and source records attributed to D Dolphin.

At least 55 records · Page 3Linked to original sources
PubMed1976

Carbon monoxide binding to pentacoordinate mercaptide-heme complexes: kinetic study on models for cytochrome P-450.

Mercaptide anions form exclusively penta-coordinate heme complexes [RS-heme] in polar and nonpolar solution over a wide range of mercaptide concentration. These complexes have a Soret peak at 408 nm and a formation constant of about 2.5 X 10(4) M(-1), and combine with CO to give a CO-cytochrome P-450 type spectrum. Kinetics of CO binding to mercaptide-heme complexes [RS-heme] have been studied by the flash photolysis method. Characteristic constants for this reaction suggest close similarities between [CH3-(CH2)3-S-heme] and cytochrome P-450. The reaction of alkoxide anion with heme has also been examined but no evidence was found for the existence of the [RO-heme-CO[ species.

Carbon Monoxide↗
PubMed1974

The cation radicals of free base and zinc bacteriochlorin, bacteriochlorophyll, and bacteriopheophytin.

One-electron oxidation of zinc tetraphenylbacteriochlorin and its metal-free base yielded stable cation radicals. Electron spin resonance hyperfine splittings were assigned by selective deuterations. These results indicate that the protons of the saturated rings of the bacteriochlorins carry large spin densities, in accord with molecular orbital calculations. Comparison in vitro of the optical spectra of bacteriochlorins and their cation radicals with those of bacteriochlorophyll show close correspondence and suggest that the electron spin resonance data from the former may also prove a guide to the biological molecule. The surprising similarity in properties between the radicals of free base and zinc bacteriochlorins is maintained in the chlorophylls: cation radicals of bacteriopheophytin and methyl pheophorbide (the free bases of bacteriochlorophyll and methyl chlorophyllide, respectively) exhibit electron spin resonance properties similar to those of their magnesium-containing derivatives. The possibility that metal-free chlorophylls participate in photosynthesis is discussed.

Journal Article↗
PubMed1974

Oxaziridines as possible intermediates in flavin monooxygenases.

The enzymatic hydroxylation reactions of flavin monooxygenases are suggested to involve an oxaziridine as the active oxygenating agent. The chemistry of these monooxygenases and their nonenzymatic model systems are consistent with an oxaziridine intermediate. Several advantages of the oxaziridine model over the previously proposed "carbonyl oxide" and flavin peroxide models are discussed.

Azirines↗