Investigations on the enzymes and toxins of staphylococci. Hydrolysis of triglycerides and other esters by lipase

Substrate specificity of Staphylococcus aureus (TEN5) lipases with isomeric oleoyl-sn-glycerol ethers as substrates

For the first time fully protected substrates with only one hydrolyzable ester bond have been used to analyze the substrate specificity of microbial lipases. In these substrates the ester is attached to the glycerol molecule in a precisely defined position. The use of three different substituents generates chirality and thus allows the analysis of positional specificities of individual lipases. Therefore, these new substrates have been used to study the enzymatic activities of two closely related lipases isolated from Staphylococcus aureus (TEN5) designated the 44 and 43 kDa lipase. The lipases, especially the 44 kDa molecule, show a high specificity for the hydrolysis of the ester in the sn-1 position (S-configuration), which is hydrolyzed by a factor of ten faster than that in the sn-3 position. In addition, the study demonstrates for the first time that the rate of hydrolysis of a fatty acid ester attached to the sn-2 position of glycerol by microbial lipases depends on the configuration of the substrate molecule.

Isolation and characterization of the extracellular lipase of Acinetobacter calcoaceticus 69 V

The extracellular lipase of Acinetobacter calcoaceticus 69 V was purified by hydrophobic interaction chromatography to homogeneity as suggested by gel electrophoretic analysis. The lipase existed as a high molecular complex of about 300 kDa, with a subunit molecular weight of 30.5 kDa being obtained by SDS-PAGE. The hydrodynamic molecular radius obtained by gel electrophoresis was 3.27 nm. The lipase had an isoelectric point of 5.5 and was stimulated by additions of deoxycholate. The activation energy for the hydrolysis of p-nitrophenyl palmitate was 39.9 kJ mol-1. Tri-, di- and monoacylglycerols were hydrolyzed. Hg2+ and p-hydroxymercuribenzoate inhibited the enzyme activity at very low concentrations. One sulfhydryl group was found per molecule of lipase.

Purification and some properties of the staphylococcal extracellular lipase

Staphylococcal lipase has been purified by application of a multistep procedure involving ammonium sulfate precipitation, and hydrophobic interaction chromatography followed by gel filtration through Sepharose CL-4B. A purified enzyme was obtained which appeared to be homogeneous by molecular sieving, polyacrylamide gel electrophoresis and sucrose gradient centrifugation. The enzyme was then subjected to physicochemical analysis. It has been found that staphylococcal lipase appears in two molecular forms: light (45 kDa) and heavy (300 kDa). Amino acid analysis indicates that lipase contains 17 amino acids with a prevalence of hydrophobic amino acids. No sulfur-containing amino acid was found in the enzyme molecule. The lipase contains about 2% sugars and some amount of lipids. The lipase preparation is stable within pH 5.0 to 9.0 and exhibits maximal activity at pH 8.0. The optimal temperature for the enzymatic reaction was established at 55 degrees C.

Separation and characterization of two isolated lipases from Staphylococcus aureus (TEN5)

The purified lipases from Staphylococcus aureus (TEN5) showing two enzymatically active protein bands on SDS-polyacrylamide gel electrophoresis have been separated by ion-exchange chromatography. The separated proteins show some properties which are different (e.g., apparent molecular weight, charge, binding of detergent, enzymatic activity towards triolein) and some which are almost identical (spur in immunodiffusion).