Guinea-pig liver leukotriene A4 hydrolase. Purification, characterization and structural properties.
Leukotriene A4 hydrolase from perfused guinea-pig liver was purified 1200-fold to near homogeneity with a yield of about 20%. Apparent values of Km and Vmax at 37 degrees C (27 microM and 68 mumol x mg-1 x min-1), turnover number, and activation energy for the conversion of leukotriene A4 into leukotriene B4 were estimated from kinetic data obtained at -10 degrees C, 0 degree C and +10 degrees C (Arrhenius plots). Physical properties including Mr (67,000-71,000), pH optimum, isoelectric point and Stokes' radius were determined. The amino acid composition and N-terminal amino acid sequence were established after carboxymethylation of the enzyme. Unlike liver cytosolic epoxide hydrolase, the purified enzyme did not catalyze the conversion of leukotriene A4 into (5S,6R)-5,6-dihydroxy-7,9-trans-11,14-cis-icosatetraenoic acid.
Haeggström
J
J
Department of Physiological Chemistry, Karolinska Institutet, Stockholm, Sweden.
Bergman
T
T
Jörnvall
H
H
Rådmark
O
O
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D004851:Epoxide Hydrolases / Q000302:isolation & purification*; D006168:Guinea Pigs; D007700:Kinetics; D008099:Liver / Q000032:analysis*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010477:Perfusion
D000596:Amino Acids; D004851:Epoxide Hydrolases; C043134:leukotriene A4 hydrolase