Publications

• Stereoselective hydrolysis of triglycerides by animal and microbial lipases.

  Rogalska E., Cudrey C., Ferrato F., Verger R.

  In the present paper, a study on the stereoselectivity of 25 lipases of animal and microbial origin towards homogeneous prochiral triglycerides is presented. All the lipases tested catalyse the hydrolysis of the chemically alike but sterically nonequivalent ester groups in trioctanoin and triolein ... >> More

  In the present paper, a study on the stereoselectivity of 25 lipases of animal and microbial origin towards homogeneous prochiral triglycerides is presented. All the lipases tested catalyse the hydrolysis of the chemically alike but sterically nonequivalent ester groups in trioctanoin and triolein with different degrees of stereobias, depending on the fatty acyl chain length of the substrate (Rogalska et al., J. Biol. Chem. 256:20271-20276, 1990). Hydrolysis of the sn-2 ester group is catalysed by very few lipases and only Candida antarctica A shows a clear preference for this position. Most of the lipases investigated (12 with trioctanoin and 16 with triolein) showed a preference for the sn-1 position. Using trioctanoin as substrate we observed a total stereoselectivity for position sn-1 with Pseudomonas sp. and Pseudomonas aeruginosa and for position sn-3 with Candida antarctica B. This was not the case with triolein as substrate. Among the 23 lipases studied here and the other two lipases described previously (Rogalska et al., J. Biol. Chem. 256:20271-20276, 1990), 17 show a higher stereoselectivity with trioctanoin than with triolein. With guinea pig pancreatic lipase and with three mold lipases (Geotrichum candidum M, Geotrichum candidum A, and Candida antarctica B), the preference switches from sn-3 to sn-1 when the acyl chain length increases from eight to 18 carbon atoms. The main conclusion to emerge from the present study is that the specific stereopreference of each lipase for a given substrate under given lipolytic conditions can be said to be its fingerprint. << Less

  Chirality 5:24-30(1993) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.

• A novel extracellular esterase from Bacillus subtilis and its conversion to a monoacylglycerol hydrolase.

  Eggert T., Pencreac'h G., Douchet I., Verger R., Jaeger K.-E.

  A novel gene lipB, which encodes an extracellular lipolytic enzyme, was identified in the Bacillus subtilis genomic DNA sequence. We have cloned and overexpressed lipB in B. subtilis and Escherichia coli and have also purified the enzyme from a B. subtilis culture supernatant to electrophoretic ho ... >> More

  A novel gene lipB, which encodes an extracellular lipolytic enzyme, was identified in the Bacillus subtilis genomic DNA sequence. We have cloned and overexpressed lipB in B. subtilis and Escherichia coli and have also purified the enzyme from a B. subtilis culture supernatant to electrophoretic homogeneity. Four different lipase assays were used to determine its catalytic activity: pH-stat, spectrophotometry, fluorimetry and the monomolecular film technique. LipB preferentially hydrolysed triacylglycerol-esters and p-nitrophenyl-esters of fatty acids with short chain lengths of </= 10 carbon atoms. Triolein, which is a typical substrate for true lipases, was not hydrolysed at all. These results led us to classify LipB as an esterase rather than a lipase. The catalytic triad of LipB consists of residues Ser78, Asp134, and His157 as demonstrated by amino-acid sequence alignments and site-directed mutagenesis. The nucleophile Ser78 is located in a lipase-specific consensus sequence, which is Ala-X-Ser-X-Gly for most Bacillus lipases. All other bacterial lipases contain a glycine residue instead of the alanine at position-2 with respect to the catalytic serine. We have investigated the role of this alanine residue by constructing LipB variant A76G, thereby restoring the lipase-specific consensus motif. When compared with LipB this variant showed a markedly reduced thermostability but an increased stability at pH 5-7. Determination of the specific activities of wild-type LipB and variant A76G using a monomolecular film of the substrate monoolein revealed an interesting result: the A76G substitution had converted the esterase LipB into a monoacylglycerol hydrolase. << Less

  Eur. J. Biochem. 267:6459-6469(2000) [PubMed] [EuropePMC]

  This publication is cited by 10 other entries.

• Studies on the substrate specificity of purified human milk lipoprotein lipase.

  Wang C.S., Kuksis A., Manganaro F.

  The fatty acid specificity of purified human milk lipoprotein lipase was studied using the C18 to C54 (total acyl carbon number) saturated and the C54 mono-, di- and triunsaturated monoacid triacylglycerols. Kinetic determinations indicated that the medium-chain triacylglycerols were better substr ... >> More

  The fatty acid specificity of purified human milk lipoprotein lipase was studied using the C18 to C54 (total acyl carbon number) saturated and the C54 mono-, di- and triunsaturated monoacid triacylglycerols. Kinetic determinations indicated that the medium-chain triacylglycerols were better substrates than long- or very short-chain saturated triacylglycerols. The unsaturated triacylglycerols were hydrolyzed at rates comparable to that of tricaprylin with triolein having the highest rate of hydrolysis of the unsaturated species tested. The enzyme attacked the primary ester bond much more readily than the secondary ester bond. The purified human milk lipoprotein lipase showed a preferential stereospecific lipolysis of the sn-1-position of the triacylglycerol molecule. << Less

  Lipids 17:278-284(1982) [PubMed] [EuropePMC]

  This publication is cited by 8 other entries.