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Human Brain Sulphotransferase and GlucuronyltransferaseDepartment of General Pathology, University of Pisa, via Roma 55, 56100 Pisa Italy
Department of General Pathology, University of Pisa, via Roma 55, 56100 Pisa Italy
Department of Neurosurgery, Medical School, University of Pisa, via Roma 55, 56100 Pisa Italy
Department of General Pathology, University of Pisa, via Roma 55, 56100 Pisa Italy 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 µM (mean ± s.d.) and 121 µM, 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.
Human & Experimental Toxicology, Vol. 9, No. 2,
65-69 (1990) |
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