engleski

Influence of 2-mercaptoethanol concentration on the activity of immobilized lipase

The aim of this study was to examine influence of three different concentrations of 2-mercaptoethanol, a well-known blocking reagent of non-occupied sites of Eupergit CM, on the activity of immobilized Thermomyces lanuginosus lipase (TLL). Enzyme immobilization on Eupergit CM was conducted in 1 M phosphate buffer pH = 7.5 for 24 hours at 25 °C, followed by filtration. Afterwards, blocking of non-occupied sites on Eupergit CM was performed with 0.2, 0.1 and 0.05 M 2-mercaptoethanol for 4 hours at 4 °C. Immobilization efficiency was monitored by determination of protein content and residual activity of lipase in filtrates, while activity retention by determination of Eupergit CM bound lipase activity. Results showed that immobilization of TLL on Eupergit CM during 24 hours, resulted with high immobilization efficiency. On average, 90.0 ± 1.5% of proteins and 98.5 ± 1.8% of lipase was found covalently bound on Eupergit CM. Blocking of non-occupied sites on Eupergit CM containing covalently bound TLL, by different concentrations of 2-mercaptoethanol caused significant reduction in lipase activity. Lipase activity retention was 13% for treatment with 0.2 M 2-mercaptoethanol, 30% for treatment with 0.1 M and 25% for treatment with 0.05 M 2-mercaptoethanol. This indicates that reduction in 2-mercaptoethanol concentration for non-occupied sites blocking of Eupergit CM, have beneficial effect on Thermomyces lanuginosus lipase activity retention. However, further investigation using blocking reagents such as glycine and aspartic acid, which does not have potential for disruption of disulphide bonds within enzyme structure, is on interest.

lipase; Thermomyces lanuginosus; immobilization; Eupergit CM

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