Fatty Acid Oxidizing Activity in a Red Marine Alga, Porphyra sp.

A crude enzyme solution prepared from fronds of Porphyra sp. showed rem arkable oxygen uptake activity when linoleic acid was added as a substrate. Fatty acid oxidizing activity was mainly present in the soluble fraction of the crude homogenate. The activity was purified 769- fold from mature fronds by ammonium sulfate fractionation, ion-exchange and hydrophobic chromatography. SDS-PAGE analysis of the purified proteins indicated that its subunit size was about 13 kDa. Gel filtration chromatography equipped with a photodiode array detector revealed that the activity was associated with a protein having a molecular weight of 12,500- 13,000. It eluted with a chromophore having the maximum absorbance at 417 nm, thus, the a protein was suggested to be a heme protein. The spectrophotometric property of the protein was highly similar to that of cytochrome c suggesting that it has heme c as a prosthetic group. The protein showed highest oxygenation activity against linoleic acid, and α-linolenic acid and arachidonic acid followed, but oleic acid could not be oxidized. From linoleic acid the protein form ed 9- and 13-hydroperoxides to the same extent, and both were shown to be racemic. These results showed that the oxidizing activity is accountable to a cytochrome, but not to a typical lipoxygenase.

SYNTHESIS OF FATTY ACIDS BY TESTICULAR TISSUE IN VITRO

The fatty acids palmitic, palmitoleic, stearic, and oleic have been isolated from rabbit testis and evidence for the synthesis of palmitic and stearic acids de novo from acetate-1-C14 is presented. ICSH did not produce demonstrable stimulation of the synthesis of these acids in vitro although the hormone stimulated the production of testosterone-C14 by the same tissue. Adrenal tissue was shown to contain palmitic, stearic, and oleic acids, and ACTH did not increase the incorporation of acetate-1-C14 into a fatty acid fraction extracted following incubation of adrenal tissue in the presence of this substrate. Fatty acid biosynthesis, therefore, is probably not influenced by the mechanisms by which tropic hormones increase steroid formation.

SYNTHESIS OF FATTY ACIDS BY TESTICULAR TISSUE IN VITRO

The fatty acids palmitic, palmitoleic, stearic, and oleic have been isolated from rabbit testis and evidence for the synthesis of palmitic and stearic acids de novo from acetate-1-C14is presented. ICSH did not produce demonstrable stimulation of the synthesis of these acids in vitro although the hormone stimulated the production of testosterone-C14by the same tissue. Adrenal tissue was shown to contain palmitic, stearic, and oleic acids, and ACTH did not increase the incorporation of acetate-1-C14into a fatty acid fraction extracted following incubation of adrenal tissue in the presence of this substrate. Fatty acid biosynthesis, therefore, is probably not influenced by the mechanisms by which tropic hormones increase steroid formation.