Jonas E. Richmond

A note on the synthesis of fatty acids in bone marrow homogenates as affected by X-radiation☆

1. 1. The synthesis of saturated and unsaturated fatty acids in bone marrow homogenates from untreated and X-radiated rabbits has been studied with α-14C-acetate as a precursor. 2. 2. Two and three-fold increases, respectively, over preradiation levels in saturated and unsaturated fatty acid synthesis were observed immediately after radiation. 3. 3. Whereas saturated fatty acid synthesis, which approached control values at 48 hours after radiation, again increased 312 times 72 hours after radiation, unsaturated fatty acid synthesis had fallen to 18% of the preradiation value. At 158 hours after radiation, the relationship between saturated and unsaturated fatty acid synthesis was reversed since unsaturated fatty acid synthesis had risen to 283% and saturated fatty acid synthesis had dropped to 58% of the preradiation value. 4. 4. Oxygen uptake and 14CO2 production increased immediately after radiation, reaching preradiation values 48 hours after exposure. 14CO2 evolution decreased steadily throughout the experimental period while oxygen uptake was unchanged 158 hours after exposure. 5. 5. Hemin synthesis after radiation has been found to behave in a manner similar to that observed in other studies. 6. 6. The term W has been introduced to denote the capacity of the bone marrow to synthesize fatty acids from α-14C-acetate.

The role of the carbon skeleton of lysine in the biosynthesis of hemoglobin

Abstract 1. 1. It has been shown that lysine-ϵ-C 14 , led to a dog, contributes significantly to the biosynthesis of the protoporphyrin IX in erythrocyte hemoglobin. 2. 2. The C 14 -activity of such hemoglobin protoporphyrin was found to be localized largely in carbon atoms C -10 and D -10 as ascertained by isolation of the two carbon atoms in question by means of the Schmidt reaction. 3. 3. A comparison of the specific millimolar C 14 -activities of protoporphyrin IX, and of glutamic and aspartic acids isolated from erythrocyte globin, suggests that the conversion of the carbon skeleton of lysine to the afore-mentioned metabolites occurs without preceding fragmentation through a five carbon intermediary metabolite which may be identical with α-ketoglutarate.

Studies on the biosynthesis of hemin in soy bean nodules

Soy bean nodule homogenates are able to incorporate the carbon atoms of acetate and glycine into hemin. Acids of the Krebs cycle, malonate and sodium azide inhibited the incorporation of the a-carbon atom of glycine into hemin. CoA and substances containing sulfhydryl groups also inhibited the above reaction. Magnesium, acetate, glycine, hydrosulfite and fluoride stimulated. The effects of various combinations of these substances were also investigated. Some implications of the results obtained are discussed.