An ultraviolet spectrophotometric assay for the screening of sn-2-specific lipases using 1,3-O-dioleoyl-2-O-α-eleostearoyl-sn-glycerol as substrate

J Lipid Res. 2012 Jan;53(1):185-94. doi: 10.1194/jlr.D019489. Epub 2011 Nov 23.

Abstract

In the present study, we propose a continuous assay for the screening of sn-2 lipases by using triacylglycerols (TAGs) from Aleurites fordii seed (tung oil) and a synthetic TAG containing the α-eleostearic acid at the sn-2 position and the oleic acid (OA) at the sn-1 and sn-3 positions [1,3-O-dioleoyl-2-O-α-eleostearoyl-sn-glycerol (sn-OEO)]. Each TAG was coated into a microplate well, and the lipase activity was measured by optical density increase at 272 nm due to transition of α-eleostearic acid from the adsorbed to the soluble state. The sn-1,3-regioselective lipases human pancreatic lipase (HPL), LIP2 lipase from Yarrowia lipolytica (YLLIP2), and a known sn-2 lipase, Candida antarctica lipase A (CALA) were used to validate this method. TLC analysis of lipolysis products showed that the lipases tested were able to hydrolyze the sn-OEO and the tung oil TAGs, but only CALA hydrolyzed the sn-2 position. The ratio of initial velocities on sn-OEO and tung oil TAGs was used to estimate the sn-2 preference of lipases. CALA was the enzyme with the highest ratio (0.22 ± 0.015), whereas HPL and YLLIP2 showed much lower ratios (0.072 ± 0.026 and 0.038 ± 0.016, respectively). This continuous sn-2 lipase assay is compatible with a high sample throughput and thus can be applied to the screening of sn-2 lipases.

Publication types

  • Validation Study

MeSH terms

  • Candida / enzymology
  • Humans
  • Lipase / metabolism*
  • Plant Oils / metabolism
  • Spectrophotometry, Ultraviolet / methods*
  • Stereoisomerism
  • Substrate Specificity
  • Triglycerides / metabolism*
  • Yarrowia

Substances

  • 1,3-O-dioleoyl-2-O-alpha-eleostearoylglycerol
  • Plant Oils
  • Triglycerides
  • tung oil
  • Lipase
  • PNLIP protein, human