Solubilization of C18‐Co A and C20‐CoA elongases from Allium porrum L. epidermal cell microsomes

The effects of n‐octyl‐β‐D‐glucopyranoside, Triton X‐100 and deoxycholate on acyl‐CoA elongation by Allium porrum L. epidermal cell microsomes showed that the Triton X‐100 specifically stimulated the synthesis of C22–C26 acids using C18‐CoA as primer, whereas the fatty acid elongation products of C20‐CoA remained essentially unchanged. n‐Octyl‐β‐D‐glucopyranoside increased the C20 and C22 fatty acid syntheses to the same extent and deoxycholate inhibited C18‐CoA and C20‐CoA elongation. The presence of two different elongation systems, as suggested by these results, has been demonstrated. After solubilization by Triton X‐100, the C18‐CoA and C20‐CoA elongases were separated by sucrose density centrifugation. The fractions corresponding to sucrose concentrations of 0.51 and 0.62 M presented the maximal activities for C18‐CoA and C20‐CoA elongases, respectively. In addition, by gel filtration on a Sephacryl S‐300 column, the C20‐CoA and the C18‐CoA elongases have estimated apparent molecular masses under detergent conditions of 600 and 350 kDa, respectively.