Glutathione transferase isoenzymes in olfactory and respiratory epithelium of cattle

Abstract

Glutathione transferase (GST) was investigated in the olfactory and respiratory epithelium of cattle. A significantly more abundant GST in terms of either protein amount or activity was found in the olfactory rather than in the respiratory epithelium. No apparent qualitative differences in the isoelectric focusing, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and HPLC profiles were noted in the reduced glutathione (GSH) affinity purified GST pool of olfactory and respiratory epithelium. Both tissues have at least six GST isoenzymes with isoelectric point values of 4.9 (peak I), 5.3 (peak II), 5.95 (peak III), 6.5 (peak IV), 7.1 (peak V) and 9.3 (peak VI). From both tissues at least seven different GST subunits can be resolved by HPLC analysis. The GST isoenzymes having pI at 5.3 and 9.3 were predominantly expressed in the olfactory than in the respiratory epithelium. These latter forms conjugate GSH efficiently with alkenals and hydroperoxides, respectively. Kinetic, immunological and structural properties, including HPLC analysis and N-terminal region amino acid sequence seem to indicate that the bovine nasal mucosa tissue in addition to a GST subunit which is orthologue to rat subunit 8 (alpha class) express tissues specific subunits.