title: Differences in hydrolytic abilities of two crude lipases from Geotrichum candidum 4013.
abstract: The fungus Geotrichum candidum 4013 produces two types of lipases (extracellular and cell-bound). Both enzymes were tested for their hydrolytic ability to p-nitrophenyl esters and compounds having a structure similar to the original substrate (triacylglycerols). Higher lipolytic activity of extracellular lipase was observed when triacylglycerols of medium- (C12) and long- (C18) chain fatty acids were used as substrates. Cell-bound lipase preferentially hydrolysed trimyristate (C14). The differences in the abilities of these two enzymes to hydrolyse p-nitrophenyl esters were observed as well. The order of extracellular lipase hydrolysis relation velocity was as follows: p-nitrophenyl decanoate > p-nitrophenyl caprylate > p-nitrophenyl laurate > p-nitrophenyl palmitate > p-nitrophenyl stearate. The cell-bound lipase indicates preference for p-nitrophenyl palmitate. The most striking differences in the ratios between the activity of both lipases (extracellular : cell-bound) towards different fatty acid methyl esters were 2.2 towards methyl hexanoate and 0.46 towards methyl stearate (C18). The Michaelis constant (K(m) ) and maximum reaction rate (V(max) ) for p-nitrophenyl palmitate hydrolysis of cell-bound lipase were significantly higher (K(m) 2.462 mM and V(max) 0.210 U/g/min) than those of extracellular lipase (K(m) 0.406 mM and V(max) 0.006 U/g/min).
authors.affiliation: Institute of Organic Chemistry and Biochemistry AS CR, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Brabcová
authors.forename: Marie
authors.initials: M
authors.lastname: Zarevúcka
authors.forename: Martina
authors.initials: M
authors.lastname: Macková
mesh_terms: D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005848:Geotrichum / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D006868:Hydrolysis; D007700:Kinetics; D008049:Lipase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D014280:Triglycerides / Q000737:chemistry / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D014280:Triglycerides; D008049:Lipase