. Biological structure and function; proceedings. Biochemistry; Cytology. EFFECTS OF THYROXINE AND RELATED COMPOUNDS ON LIVER MITOCHONDRIA 19 antimycin A. A further valuable property of this preparation was that it also contained the external type of DPNH-cytochrome c reductase, known to occur in liver mitochondria and characterized by an insensitivity to amytal and antimycin A [38, 39, 47, 91-95]. IOOL 02(+cytc). DCPIP D-?sanrtmofhyroxine ,mM Fig. 9. Effect of desaminothyroxine on the oxidation of DPNH by various electron acceptors in mitochondrial fragments prepared according to Kie
. Biological structure and function; proceedings. Biochemistry; Cytology. EFFECTS OF THYROXINE AND RELATED COMPOUNDS ON LIVER MITOCHONDRIA 19 antimycin A. A further valuable property of this preparation was that it also contained the external type of DPNH-cytochrome c reductase, known to occur in liver mitochondria and characterized by an insensitivity to amytal and antimycin A [38, 39, 47, 91-95]. IOOL 02(+cytc). DCPIP D-?sanrtmofhyroxine ,mM Fig. 9. Effect of desaminothyroxine on the oxidation of DPNH by various electron acceptors in mitochondrial fragments prepared according to Kielley and Kielley [Ho]. All assay systems contained 0-02 M phosphate buffer, pH 7-5, and Q-1 DPNH, in a final volume of 3 ml. In the case of O2 as acceptor, either no further additions were made (line marked "O.,"), or 0-005 cytochrome c was added (" O., (+ cyt. c.)"), and the oxidation of DPXH was followed at 340 m/x. In the case of 2,6-dichlorophenolindophenol ("DCPIP") as terminal electron acceptor, the dyestuff was added in a final concentration of 0-04 mM, and its reduc- tion was followed at 600 m/t; in the case of cytochrome c (" cyt. c ") this was added in a final concentration of 0-05 mM, and its reduction was followed at 550 m/x. In both latter cases, 0-33 mM KCN was included in the test. " loo^^o activity" was (in terms of /xmoles DPNH oxidized/min. per g. liver): 0-146 with , 0-218 with , (+ cyt. r), 0-620 with cyt. r, and 0-487 with DCPIP as electron acceptor. As can be seen in Fig. 9, desaminothyroxine greatly inhibited the DPNH oxidase activity of the Kielley and Kielley preparation as measured without added cytochrome r, as well as the diaphorase activity as measured. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original IUB/IUBS Inter
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