PROPERTIES OF IMMOBILIZED AND FREE LIPASE FROM RHIZOPUS COHNII
 
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Pol. J. Food Nutr. Sci. 2003;53(3):39–44
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ABSTRACT
Rhizopus cohnii lipase was immobilized by adsorption on porous chitosan polyphosphate beads. The obtained preparation, active against fatty acids esters of p-nitrophenol and against olive oil, was characterised and compared with the free enzyme. Both lipase forms displayed the highest activity at pH 8-9. The optimum activity temperature of free and immobilized lipase was 37oC and 30oC respectively. Immobilization did not significantly change the thermal stability of lipase in comparison with the free enzyme. Both forms of the enzyme were stable at 30oC, they lost half of their activity within 45-50 min at 50oC, and at 60oC they were fully inactivated within 10 min. Affinity to p-nitrophenylpalmitate (pNPP) for both the free and immobilized lipase was identical and amounted to Km = 0.2 mmol/L. With the use of HPLC, enzymatic hydrolysis of olive oil by the free and immobilized lipase was compared with the chemical hydrolysis of this substrate. It was found that both forms of the enzyme were active only against emulsified substrate, and the chromatograms of products of reactions catalysed by free and immobilized lipase showed no qualitative differences. Among the products of olive oil degradation by both forms of the enzyme, fractions identified as palmitic and linoleic acids were detected, whereas oleic acid, normally generated in the largest amount after chemical hydrolysis, was not detected.
ISSN:1230-0322