심해퇴적물 메타게놈으로부터 저온 적응된 신규 리파제의 특성

Abstract

To obtain novel biocatalysts, 8,823 clones library in Escherichia coli using fosmid with DNA extracted directly from deep-sea sediments had previously been constructed. The isolation of the lipase gene screened on tricaprylin-containing agar plates. Sequence analysis appeared an open reading frame (EML1) consisting of 915 nucleotides that encoded a protein (EML1) of 304 amino acid with a molecular mass 33,600 Da. We performed gene expression and purification of the recombinant protein. The enzyme was stable between pH 8 and 8.5, and the optimal pH for the enzymatic hydrolysis of olive oil was about 8. The optimal temperature for EML1 was 25 ℃, and it was unstable at temperature higher than 40 ℃. The activation energy for the hydrolysis of olive oil was determined to be 3.28 kcal/mol in the temperature range 5 to 30 ℃. The enzyme was increased lipase activity in the presence of Zn2+, Mg2+, Cu2+ and Fe2+ but was inhibited by Ca2+. The addition of detergents enhanced the enzyme activity but containing SDS almost abolished lipase activity. When triglyceride substrates of various chain-lengths were examined, the lipase showed highest activity towards trilaurin (C12). Natural substrates presented high lipase activity for saturated fatty acid such as coconut oil, palm oil.