Untersuchungen über Enzymaktivitäten der Leberzelle bei Vitamin‐E‐Mangel

The enzymatic elongation of acyl‐CoA esters by malonyl‐CoA, respectively de novo synthesis of fatty acids from malonyl‐CoA by liver microsomes and non particulate fraction of α‐tocopherol deficient rats is diminished versus controls. However, liver microsomes of vitamin E deficient rats synthesize more eicosatetraenic acid from γ‐linolenic acid and more γ‐linolenic acid from linolic acid than do those of tocopherol supplemented animals. It has often been shown that the liver phosphatides of tocopherol deficient rats contain more arachidonic acid than those of controls, a fact which can be explained now by increased activity of the enzymes involved in the biosynthesis of arachidonic acid. Certain polyenic fatty acids are more rapidly synthesized in the absence of naturally occuring antioxidants. Some enzymes of the respiratory chain have also been examined. No vitamin E deficiency effect has been found on enzymes such as gluconate‐6‐P‐dehydrogenase, isocitrate‐dehydrogenase, malate‐dehydrogenase and lactate dehydrogenase contained in the non particulate fraction. Sonicated mitochondria of tocopherol deficient rats show a greater activity towards cytochrome, oxydase and β‐hydroxy‐acetyl‐CoA‐dehydrogenase than controls, possibly due to ultrastractural alteration of this particle.