A reaction between tryptophan and ascorbic acid: A possible source of error in the assay of tryptophan oxygenase (tryptophan pyrrolase)
✍ Scribed by Gene A. Morrill; Leonard A. Feiner; Adele B. Kostellow
- Publisher
- Elsevier Science
- Year
- 1968
- Tongue
- English
- Weight
- 403 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
335 diluted) was measured at 550 and 565 nm (3) and the ratio (OD& OD,,, = 0.775/0.115) found to be 6.7 indicating a percentage reduction of 84% (4). For use in the cytochrome oxidase assay, the ratio should be greater than 6 (3,4).
Storage of the reduced cytochrome c at 3°C proved that it was stable for at least three days. The reduced pigment becomes autoxidizable only at high temperatures (70-100°C) and at extreme values of pH (above 13 and below 4) (1).
Although this met.hod has been used only for t.he separation of ascorbate from reduced cytochrome c, it is clearly likely that the separation of the pigment from other reducing agents of comparable molecular size could he achieved by a similar technique.
Note: Since the development of this method, it has been brought to t,he attention of the author that a brief description of a similar method may be found in C. E. R. Maddox, Ph. D. Thesis, University of Birmingham, 1965. L., in "Methods in Enzymology" (9. P. Colowick and ?;. 0. Kaplan, eds.). Vol. 2, p. 732. Academic Press,