Leukotriene A4 hydrolase in the human B-lymphocytic cell line Raji: indications of catalytically divergent forms of the enzyme.
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Odlander B, Claesson HE, Bergman T, Radmark O, Jornvall H, Haeggstrom JZ
Leukotriene A4 hydrolase in the human B-lymphocytic cell line Raji: indications of catalytically divergent forms of the enzyme.
Arch Biochem Biophys. 1991 May 15;287(1):167-74.
- PubMed ID
- 1897988 [ View in PubMed]
- Abstract
Leukotriene A4 hydrolase was purified 1400-fold, with an approximate yield of 25%, to apparent homogeneity from the human B-lymphocytic cell line Raji. The purification included ammonium sulfate precipitations followed by anion exchange, hydrophobic interaction, and molecular exclusion fast protein liquid chromatography. Kinetic properties at 2 degrees C varied between different enzyme preparations. Two patterns were observed, one with a Km of about 12 microM and Vmax of about 1.1 mumol LTB4/mg protein/min which correlated well with the properties of the human leukocytic LTA4 hydrolase. In other enzyme preparations a higher catalytic activity was observed. These enzyme batches did not obey Michaelis-Menten kinetics but were compatible with a mixture of enzymatic species. Heat treatment (60 degrees C) led to a time-dependent decline in catalytic activity. However, certain enzyme preparations contained a subfraction of enzymatic activity which was more resistant to heat treatment, yielding a biphasic inactivation pattern. It is thus suggested, on the basis of the kinetic properties and the heat-inactivation pattern, that these enzyme preparations contained an addition form of LTA4 hydrolase.