Characteristics of lipase-catalysed hydrolysis of triacylglycerols in Aerosol-OT/iso-octane reverse-micellar media

M. T. Patel, R. Nagarajan, Arun Kilara

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Abstract

In a reverse-micellar system of Aerosol-OT [bis-(2-ethylhexyl) sodium sulphosuccinate]/iso-octane, triacylglycerols (TAG) could be hydrolysed up to 6098%, depending upon the enzyme source. Hydrolysis reactions obeyed Michaelis-Menten kinetics and exhibited a linear relationship of the initial rate with enzyme concentration, which suggests that the reaction rate in reverse micelle is kinetically controlled and not limited by mass-transfer considerations. The kinetic parameters for hydrolytic reactions are related to enzyme source and physicochemical characteristics of substrate. The Michaelis constant (K(m)) and maximum reaction rate (V(max.)) for hydrolysis of olive (Olea europaea) TAG by Rhizopus javanicus lipase were significantly higher than that by Candida cylindracea lipase. The kinetic parameters for coconut TAG were lower than that of olive TAG. The K(m) and V(max.) for TAG hydrolysis increased with increase in reaction temperature and decreased with increase in reaction pH. Buffer components may have considerable effect on enzyme activity and R-activity (R is the molar ratio of water to surfactant) profile of lipases in reverse micelles. When considering the influence of reaction variables on lipase-catalysed reactions for practical purposes, the initial rate as well as reaction rate over extended periods of time should be studied. The effect of reaction variables, surfactant concentration as an example, could be different on initial rate and degree of hydrolysis at 24 h. Lipase activity is rapidly reduced in reverse-micellar media in absence of any substrate. The effect is severe at higher value of R. The stability of enzyme in reverse micelles is also related to enzyme source. Reverse-micellar systems, in conjunction with other bioseparation techniques, could be used for lipase-catalysed bioconversion of TAG and other sparingly-water-soluble compounds for the production of value-added products.

Original languageEnglish (US)
Pages (from-to)1-14
Number of pages14
JournalBiotechnology and Applied Biochemistry
Volume22
Issue number1
StatePublished - Jan 1 1995

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All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Bioengineering
  • Molecular Medicine
  • Biomedical Engineering
  • Applied Microbiology and Biotechnology
  • Drug Discovery
  • Process Chemistry and Technology

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