Purification, immobilization and characterization of linoleic acid isomerase on modified palygorskite

Abstract

Linoleic acid isomerase from Lactobacillus delbrueckii subsp. bulgaricus 1.1480 was purified by DEAE ion-exchange chromatography and gel filtration chromatography. An overall 5.1% yield and purification of 93-fold were obtained. The molecular weight of the purified protein was ~41 kDa which was analyzed by SDS-PAGE. The purified enzyme was immobilized on palygorskite modified with 3-aminopropyltriethoxysilane. The immobilized enzyme showed an activity of 82 U/g. The optimal temperature and pH for the activity of the free enzyme were 30 °C and pH 6.5, respectively; whereas those for the immobilized enzyme were 35 °C and pH 7.0, respectively. The immobilized enzyme was more stable than the free enzyme at 30-60 °C, and the operational stability result showed that more than 85% of its initial activity was retained after incubation for 3 h. The K (m) and V (max) values of the immobilized enzyme were found to be 0.0619 mmol l(-1) and 0.147 mmol h(-1) mg(-1), respectively. The immobilized enzyme had high operational stability and retained high enzymatic activity after seven cycles of reuse at 37 °C.

Esterification of conjugated linoleic acid by yeasts for increasing the value of plant materials

“…shermanii and L. debruechii ssp. bulgaricus, were reported to be soluble after sonication-assisted extraction (Lin et al, 2002;Lin, 2006;Farmani et al, 2010;You et al, 2011).…”

“…Crude enzyme preparations containing LAI extracted from lactobacilli and propionibacteria have also been investigated as biocatalysts for CLA production (Lin et al, 2002 and2003;Lin, 2006;Irmak et al, 2006;Kishino et al, 2011). Lysozyme treatment and sonication or homogenization were used for cell disruption, followed by collection and concentration of the enzyme fractions (Lin et al, 2002 and2003;Lin, 2006;You et al, 2011, Peng et al, 2007. The reported CLA levels obtained by these enzyme systems have been modest.…”

“…Immobilization of purified LAI from L. delbrueckii ssp. bulgaricus 1.1480 on modified palygorskite, a fibrillar type of hydrated magnesium aluminium silicate, enhanced the thermal and operational stability of the enzyme (You et al, 2011). The immobilized enzyme activity was less sensitive to temperature and pH than the free enzyme.…”