Biomaterial Database

Kinetic studies on the reduction of metmyoglobins by ascorbic acid. 1983

K Tsukahara, and Y Yamamoto

The kinetics of the reduction of metmyoglobins by ascorbic acid (H2A) were studied under a nitrogen atmosphere at 25 degrees C, at an ionic strength of 0.30 M (NaCl), and between pH 7.18 and 8.09. Neither Tris-HCl nor phosphate buffers had any effect on the reduction of metmyoglobin. Imidazol and 1-methylimidazol accelerated this reaction, but N3- and CN- ions inhibited it. It is concluded that the reduction of imidazolmetmyoglobin or 1-methylimidazolmetmyoglobin is faster than that of aquametmyoglobin and that neither azidometmyoglobin nor cyanometmyoglobin can be reduced by ascorbate under the present experimental conditions. The second-order rate constants were determined for the reductions of aqua-, imidazol-, and 1-methylimidazolmetmyoglobin by ascorbate (HA- and A2-). The higher reactivity of imidazolmetmyoglobin with ascorbate may be due to the easy transfer of an electron of ascorbate to partially exposed imidazol or porphyrin ring because of expansion of the heme pocket induced by the coordination of imidazol.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008786	Metmyoglobin	Myoglobin which is in the oxidized ferric or hemin form. The oxidation causes a change in color from red to brown.	Ferrimyoglobin
D008956	Models, Chemical	Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.	Chemical Models,Chemical Model,Model, Chemical
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
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
D006420	Hemeproteins	Proteins that contain an iron-porphyrin, or heme, prosthetic group resembling that of hemoglobin. (From Lehninger, Principles of Biochemistry, 1982, p480)	Hemeprotein,Heme Protein,Heme Proteins,Protein, Heme,Proteins, Heme
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001205	Ascorbic Acid	A six carbon compound related to glucose. It is found naturally in citrus fruits and many vegetables. Ascorbic acid is an essential nutrient in human diets, and necessary to maintain connective tissue and bone. Its biologically active form, vitamin C, functions as a reducing agent and coenzyme in several metabolic pathways. Vitamin C is considered an antioxidant.	Vitamin C,Ascorbic Acid, Monosodium Salt,Ferrous Ascorbate,Hybrin,L-Ascorbic Acid,Magnesium Ascorbate,Magnesium Ascorbicum,Magnesium di-L-Ascorbate,Magnorbin,Sodium Ascorbate,Acid, Ascorbic,Acid, L-Ascorbic,Ascorbate, Ferrous,Ascorbate, Magnesium,Ascorbate, Sodium,L Ascorbic Acid,Magnesium di L Ascorbate,di-L-Ascorbate, Magnesium
D014907	Whales	Large marine mammals of the order CETACEA. In the past, they were commercially valued for whale oil, for their flesh as human food and in ANIMAL FEED and FERTILIZERS, and for baleen. Today, there is a moratorium on most commercial whaling, as all species are either listed as endangered or threatened.	Beaked Whales,Berardius,Caperea,Dwarf Sperm Whale,Giant Bottle-Nosed Whales,Goose-Beaked Whale,Gray Whale,Mesoplodon,Narwhals,Pygmy Right Whale,Pygmy Sperm Whale,Right Whale, North Atlantic,Right Whale, Southern,Ziphiidae,Ziphius,Eschrichtius robustus,Eubalaena australis,Grey Whale,Monodon monoceros,North Atlantic Right Whale,Beaked Whale,Bottle-Nosed Whale, Giant,Bottle-Nosed Whales, Giant,Dwarf Sperm Whales,Giant Bottle Nosed Whales,Giant Bottle-Nosed Whale,Goose Beaked Whale,Goose-Beaked Whales,Gray Whales,Grey Whales,Narwhal,Pygmy Right Whales,Pygmy Sperm Whales,Right Whale, Pygmy,Right Whales, Pygmy,Right Whales, Southern,Southern Right Whale,Southern Right Whales,Sperm Whale, Dwarf,Sperm Whale, Pygmy,Sperm Whales, Dwarf,Sperm Whales, Pygmy,Whale,Whale, Grey,Whale, Southern Right,Whales, Grey,Whales, Southern Right