Fatty acid α-oxidation of tetradecylthioacetic acid and tetradecylthiopropionic acid in cucumber (Cucumis sativus)

Fatty acid α-oxidation in cucumber (Cucumis sativus) involves enzymatic conversion of long-chain C_n-fatty acids to the C_(n−1)-aldehyde and CO₂. However, the mechanism of this process is not well understood. In this study, the α-oxidation of the fatty acid analogues tetradecylthioacetic acid (TTA) and tetradecylthiopropionic acid (TTP) with a sulphur atom substituting the methylene group in positions 3 and 4, respectively, was investigated and compared to palmitic acid. Both [1-¹⁴C]TTA and [1-¹⁴C]TTP could be α-oxidised in the cucumber subcellular 150 000×g_max fraction. [1-¹⁴C]TTP was an even better substrate compared to the natural palmitic acid, while [1-¹⁴C]TTA was α-oxidised to a lower extent. [2-¹⁴C]TTA revealed no ¹⁴CO₂, indicating that only one cycle of α-oxidation occurred. TTA was an inhibitor of the palmitic acid α-oxidation, and the inhibitory effects were examined.