Human brain sulphotransferase and glucuronyltransferase.
The activities of cytosolic sulphotransferase (ST) and microsomal glucuronyltransferase (GT) were measured with 1-naphthol as the substrate in three frontal cortex, three temporal cortex, one parietal cortex, one occipital cortex and two cerebellar cortex specimens from human brain. The average activity was 11.7 +/- 4.2 pmol/min/mg protein/(ST) and 26.8 +/- 13.6 pmol/min/mg protein (GT). The kinetics of ST were studied varying the concentration of 1-naphthol in five brain specimens (temporal cortex, temporal subcortex, occipital cortex, cerebellum cortex and frontal cortex) whereas those of GT were studied in a sample obtained by pooling the microsomal fractions from the following eight brain tissues: one frontal cortex, four temporal cortex, one parietal cortex and two cerebellar cortex specimens. The Km of the first and second enzyme was 1.55 +/- 0.47 microM (mean +/- s.d.) and 121 microM, respectively. The Vmax values were 13.70 +/- 8.16 (mean +/- s.d.) pmol/min/mg protein (ST) and 103 pmol/min/mg protein (GT). Vmax/Km was ten times higher for ST than GT. These data suggest that ST is the predominant pathway at low concentrations of 1-naphthol whereas at higher concentrations, GT becomes the predominant pathway.
Viani
A
A
Department of General Pathology, Medical School, University of Pisa, Italy.
Temellini
A
A
Tusini
G
G
Pacifici
G M
GM
D000368:Aged; D001921:Brain / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D005260:Female; D014453:Glucuronosyltransferase / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008297:Male; D008861:Microsomes / Q000201:enzymology; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000032:analysis; D015238:Sulfotransferases / Q000378:metabolism*
D009419:Nerve Tissue Proteins; D014453:Glucuronosyltransferase; D015238:Sulfotransferases