Activities of Candida rugosa lipase and other esterolytic enzymes coated on glass beads and suspended in substrate and water vapor: enzymes in thin liquid films.
Candida rugosa lipase was enzymatically active when coated on glass beads and exposed to mixtures of substrate and water vapor over a range of relative humidities up to 100%. Evidence was obtained for operation of the enzyme in a thin liquid film of concentrated buffer on the surface of the glass beads. Formation of the thin film was associated with hygroscopicity of the buffer used to suspend the enzyme in preparation of the enzyme-coated beads. At some buffer concentrations estimated to be on the bead surface, the enzyme was partially soluble and both soluble and insoluble forms were enzymatically active. The vapor mode of operation over a range of relative humidities had comparatively small effects on kinetic constants for hydrolysis of ethyl acetate, which were also similar to those in phosphate buffer. The extent of reaction occurred in the order hydrolysis greater than alcoholysis greater than ester interchange greater than esterification. Reaction preference between alcoholysis and hydrolysis changed as acyl chain length of substrate increased with C. rugosa lipase, as well as with Rhizopus arrhizus lipase and porcine liver esterase, with details depending on the enzyme. The vapor mode approach has the potential of being used with a wide variety of substrates, as shown by the ability to obtain hydrolysis at 30 degrees C with substrate vapor pressures as low as 0.08 mm Hg and with substrates with boiling points as high as 206 degrees C.
Division of Biological Sciences, National Research Council of Canada, Ottawa, Ontario.
N W
NW
Ross
H
H
Schneider
D002175:Candida / Q000201:enzymology*; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000378:metabolism*; D004950:Esterases / Q000378:metabolism*; D005898:Glass; D008049:Lipase / Q000378:metabolism*; D013379:Substrate Specificity; D014867:Water
D004800:Enzymes, Immobilized; D014867:Water; D004950:Esterases; D008049:Lipase