| Description |
ix, 74 leaves : illustrations ; 29 cm. |
| Summary |
"A porcine thyroid enzyme was extracted from thyroid tissue by homogenization and differential centrifugation. The enzyme was capable of metabolizing both 3-iodotyrosine and 3,5-diiodotyrosine. All of the thyroid subcellular particles produced a fluorescent compound when incubated with these substrates. When the 1,000 x g sediment was supplemented with the 48,000 x g supernatant a second compound was formed. The compound was UV absorbing and has been identified as either 3-iodo-4-hydroxybenzaldehyde or 3,5-diiodo-4-hydroxybenzaldehyde depending upon which substrate was used. The 1,000 x g sediment was solubilized with 1% Conoco 1012-6 detergent. The activating factor in the 48,000 x g supernatant was shown to be a macromolecule, probably a protein, by dialysis and ammonium sulfate precipitation. The enzymes in both fractions are required to form 3-iodo-4-hydroxybenzaldehyde. Conversion of the reaction products to their dinitrophenylhydrazones followed by paper chromatography indicated that the benzaldehydes were formed by decomposition of the corresponding p-hydroxyphenylpyruvic acid. This rules out the enzymatic formation of the benzaldehydes. This study lends support to model system studies which have suggested that 3,5 diiodo-4- hydroxyphenylpyruvic acid should be an intermediate in the formation of thyroxine"--Abstract, leaf ii. |
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