Abstract:

【Objective】 The attributes of linoleate isomerases from both Propionibacteriu freudenreichii ssp. shermanii and Lactobacillu plantarum were studied to understand the different characters of linoleate isomerase originated from different strains. 【Method】 Dynamic and characteristic parameter such as Michaelis constant, molecular weight of linoleate isomerase with different origins were determined using the method of enzyme activity analysis and electrophoresis. The peptide mass fingerprints produced by P. freudenreichii ssp. shermanii and L. plantarum linoleate isomerase were studied by HPLC–ESI–MS system. 【Result】 The optimum pH for P. freudenreichii ssp. shermanii linoleate isomerase was 8.0 and the optimum temperature was about 30℃. The Km and Vmax of linoleic acid was 20.53 μmol•L-1 and 0.44 μg•ml-1•min-1. The optimum pH for L. plantarum linoleate isomerase was 7.5 and the optimum temperature was about 50℃. The Km and Vmax of linoleic acid was 17.85 μmol•L-1 and 0.73 μ•ml-1•min-1, respectively. Molecular structure of linoleate isomerase produced by P. freudenreichii ssp. shermanii and L. plantarum showed some extent homogeny on sequences. 【Conclusion】 The linoleate isomerase originated from the two strains has different attributes. The sequences of both linoleate isomerases have some extent homogeny and the characteristic parameters of experimental linoleate isomerase are different from those of reported.

Key words: conjugated linoleic acid (CLA), L. plantarum, P. freudenreichii ssp. shermanii, linoleate isomerase