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As an alternative, ascorbic acid can be treated with iodine in excess, followed by back titration with sodium thiosulfate using starch as an indicator. [40] This iodometric method has been revised to exploit the reaction of ascorbic acid with iodate and iodide in acid solution. Electrolyzing the potassium iodide solution produces iodine, which ...
The Reichstein process in chemistry is a combined chemical and microbial method for the production of ascorbic acid from D-glucose that takes place in several steps. [1] This process was devised by Nobel Prize winner Tadeusz Reichstein and his colleagues in 1933 while working in the laboratory of the ETH in Zürich.
Ascorbic acid efflux by embryos of dicot plants is a well-established mechanism of iron reduction and a step obligatory for iron uptake. [a] All plants synthesize ascorbic acid. Ascorbic acid functions as a cofactor for enzymes involved in photosynthesis, synthesis of plant hormones, as an antioxidant and regenerator of other antioxidants. [96]
An example of a mineral ascorbate drug is sodium ascorbate injections (the acid form, ascorbic acid, of vitamin c is too acidic for injections). Ascorbate salts may be better tolerated by the human body than the corresponding weakly acidic ascorbic acid. Ascorbates are highly reactive antioxidants used as food preservatives. [2]
As the sodium salt of ascorbic acid, it is known as a mineral ascorbate. It has not been demonstrated to be more bioavailable than any other form of vitamin C supplement. [2] Sodium ascorbate normally provides 131 mg of sodium per 1,000 mg of ascorbic acid (1,000 mg of sodium ascorbate contains 889 mg of ascorbic acid and 111 mg of sodium).
Dehydroascorbic acid (DHA) is an oxidized form of ascorbic acid (vitamin C). It is actively imported into the endoplasmic reticulum of cells via glucose transporters. [ 1 ] It is trapped therein by reduction back to ascorbic acid by glutathione and other thiols . [ 2 ]
Ascorbate peroxidase (or L-ascorbate peroxidase, APX or APEX) (EC 1.11.1.11) is an enzyme that catalyzes the chemical reaction. L-ascorbate + H 2 O 2 dehydroascorbate + 2 H 2 O. It is a member of the family of heme-containing peroxidases.
These three reactions are catalyzed by large, multi-subunit enzymes prolyl 4-hydroxylase, prolyl 3-hydroxylase, and lysyl 5-hydroxylase, respectively. These enzymes require iron (as well as molecular oxygen and α-ketoglutarate). They consume oxygen (the oxidant) and ascorbic acid (vitamin C, the reductant).