title: Nucleotide sequencing, purification, and biochemical properties of an arylesterase from Lactobacillus casei LILA.
abstract: An esterase gene, designated estB, was isolated from a genomic library of Lactobacillus casei LILA. Nucleotide sequencing of the estB gene revealed a 954-bp open reading frame encoding a putative peptide of 35.7 kDa. The deduced amino acid sequence of EstB contained the characteristic GXSXG active-site serine motifidentified in most lipases and esterases. An EstB fusion protein containing a C-terminal 6-histidine tag was constructed and purified to electrophoretic homogeneity by affinity chromatography. The native molecular weight of EstB was 216.5 +/- 2.5 kDa, while the subunit molecular weight was 36.7 +/- 1.0 kDa. Optimum pH, temperature, and NaCl concentration for EstB were determined to be pH 7.0,50 to 55 degrees C, and 15% NaCl, respectively. EstB had significant activity under conditions simulating those of ripening cheese (pH 5.1, 10 degrees C, and 4% NaCl). Kinetic constants (KM and Vmax) were determined for EstB action on a variety of ethyl esters and ester compounds consisting of substituted phenyl alcohols and short n-chain fatty acids. For comparison purposes, EstA from Lb. helveticus CNRZ32 was purified to electrophoretic homogeneity and its substrate selectivity determined in a similar fashion. Different substrate selectivities were observed for EstB and EstA.
authors.affiliation: Department of Food Science, University of Wisconsin-Madison, Madison 53706, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Fenster
authors.forename: K L
authors.initials: KL
authors.lastname: Parkin
authors.forename: J L
authors.initials: JL
authors.lastname: Steele
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification; D002611:Cheese / Q000382:microbiology; D002846:Chromatography, Affinity; D015723:Gene Library; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007780:Lacticaseibacillus casei / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016366:Open Reading Frames; D017421:Sequence Analysis; D012965:Sodium Chloride; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D012965:Sodium Chloride; D002265:Carboxylic Ester Hydrolases; C019734:arylesterase