Biomaterial Database

Magnetic-circular-dichroism studies of haem a and its derivatives. 1978

T Brittain, and C Greenwood, and J P Springall, and A J Thomson

The low-temperature m.c.d.(magnetic-circular-dichroism) spectra of haem a derivatives are presented. It is shown that reduced haem a in pyridine contains the low-spin ferrous ion and that oxidized haem a in the presence of excess imidazole has the low-spin ferric form. Both the m.c.d. and the absorption spectra of haem a in excess pyridine are changed by the addition of excess sodium dithionite into a form similar to that of haems b and c. This is interpreted in terms of an attack, by reduced pyridine, at the 8-formyl group of the haem a ring. This leads to a partial assignment of the electronic spectrum of haem a.

UI	MeSH Term	Description	Entries
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D011725	Pyridines	Compounds with a six membered aromatic ring containing NITROGEN. The saturated version is PIPERIDINES.
D002621	Chemistry	A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D004227	Dithionite	Dithionite. The dithionous acid ion and its salts.	Hyposulfite,Sodium Dithionite,Dithionite, Sodium
D006418	Heme	The color-furnishing portion of hemoglobin. It is found free in tissues and as the prosthetic group in many hemeproteins.	Ferroprotoporphyrin,Protoheme,Haem,Heme b,Protoheme IX
D013054	Spectrophotometry, Atomic	Spectrophotometric techniques by which the absorption or emmision spectra of radiation from atoms are produced and analyzed.	Spectrophotometry, Atomic Absorption,AA Spectrophotometry,AE Spectrophotometry,Atomic Absorption Spectrophotometry,Atomic Emission Spectrophotometry,Atomic Spectrophotometry,Inductively Coupled Plasma Atomic Emission Spectrophotometry,Inductively Coupled Plasma Atomic Emission Spectroscopy,Spectrophotometry, Atomic Emission,AA Spectrophotometries,AE Spectrophotometries,Absorption Spectrophotometry, Atomic,Emission Spectrophotometry, Atomic,Spectrophotometries, AA,Spectrophotometries, AE,Spectrophotometry, AA,Spectrophotometry, AE
D055598	Chemical Phenomena	The composition, structure, conformation, and properties of atoms and molecules, and their reaction and interaction processes.	Chemical Concepts,Chemical Processes,Physical Chemistry Concepts,Physical Chemistry Processes,Physicochemical Concepts,Physicochemical Phenomena,Physicochemical Processes,Chemical Phenomenon,Chemical Process,Physical Chemistry Phenomena,Physical Chemistry Process,Physicochemical Phenomenon,Physicochemical Process,Chemical Concept,Chemistry Process, Physical,Chemistry Processes, Physical,Concept, Chemical,Concept, Physical Chemistry,Concept, Physicochemical,Concepts, Chemical,Concepts, Physical Chemistry,Concepts, Physicochemical,Phenomena, Chemical,Phenomena, Physical Chemistry,Phenomena, Physicochemical,Phenomenon, Chemical,Phenomenon, Physicochemical,Physical Chemistry Concept,Physicochemical Concept,Process, Chemical,Process, Physical Chemistry,Process, Physicochemical,Processes, Chemical,Processes, Physical Chemistry,Processes, Physicochemical