[Influence of monodehydroascorbate on the acyl-CoA-desaturase system of rat liver microsomes (author's transl)].

The microsomal NADH- as well as the ascorbate-dependent fatty acid desaturation are diminished by monodehydroascorbate. This effect can be neutralized by borate. Borate forms an adduct with didehydroascorbate and thus prevents the formation of monodehydroascorbate. The ascorbate-dependent oleate formation is increased significantly by the same reaction (p less than 0.01). The NADH-dependent reaction is diminished by parallel reactions of the desaturase system and L-ascorbate: ferricytochrome b5 oxidoreductase at ferrocytochrome b5. In the case of the ascorbate-dependent reaction the diminished oleate formation is caused by the more positive oxidation state of cytochrome b5 in presence of monodehydroascorbate.