Reversible microsomal binding of hepatic aldolase.
نویسندگان
چکیده
Fructose-1,6-bisphosphate aldolase (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate lyase, EC 4.1.2.13) partitions between the microsomes and the cytosol when a rat liver homogenate is fractionated by differential centrifugation. Gel electrophoresis and immunodiffusion indicate that the one isozyme present in the liver of the young adult rat is found in both fractions. The association of the aldolase with membranes is differentially sensitive to a variety of metabolites and inorganic salts. In the absence of cellular salts, 1 mM fructose 1,6-bisphosphate or glucose 1,6-bisphosphate elutes 50% of the enzyme from the microsomes. About 9 mM Pi or citrate is necessary to produce the same effect. With other metabolites or inorganic salts higher concentrations are required. The fraction of total enzyme which partitions with the microsomes when a homogenate is submitted to high speed centrifugation, correlates inversely with the level of fructose 1,6-bisphosphate in the supernatant solution and this concentration is higher when the tissue concentration in the homogenate is greater. The Km for fructose 1,6-bisphosphate of 3 . 10(-4) for aldolase bound to microsomes is decreased to 6 . 10(-6) M when the enzyme is dissociated from the membranes with salt. These observations appear relevant to the ongoing discussion regarding the physiological relevance of the subcellular localization of glycolytic enzymes.
منابع مشابه
Interspecies variation in the hepatic biotransformation of zearalenone: Evidence for bio-inactivation of mycoestrogen zearalenone in sturgeon fish
Zearalenone (ZEA) as mycoestrogen is found in human foods and animal feeds. Its estrogenic potency depends on its biotransformation fate. The hepatic biotransformation of ZEA in two species of sturgeon fish (Acipenser persicus and Huso huso) was investigated. ZEA was incubated with the hepatic microsomal and post-mitochondrial sub-fractions in the presence of NADPH and the metabolites were dete...
متن کاملInterspecies variation in the hepatic biotransformation of zearalenone: Evidence for bio-inactivation of mycoestrogen zearalenone in sturgeon fish
Zearalenone (ZEA) as mycoestrogen is found in human foods and animal feeds. Its estrogenic potency depends on its biotransformation fate. The hepatic biotransformation of ZEA in two species of sturgeon fish (Acipenser persicus and Huso huso) was investigated. ZEA was incubated with the hepatic microsomal and post-mitochondrial sub-fractions in the presence of NADPH and the metabolites were dete...
متن کاملIon-trapping, microsomal binding, and unbound drug distribution in the hepatic retention of basic drugs.
This study investigated the relative contribution of ion-trapping, microsomal binding, and distribution of unbound drug as determinants in the hepatic retention of basic drugs in the isolated perfused rat liver. The ionophore monensin was used to abolish the vesicular proton gradient and thus allow an estimation of ion-trapping by acidic hepatic vesicles of cationic drugs. In vitro microsomal s...
متن کاملIn vitro reduction of zearalenone to β-zearalenol by rainbow trout (Oncorhynchus mykiss) hepatic microsomal and post-mitochondrial subfractions
Mycoestrogen zearalenone (ZEA) is found in human foods and animal feeds. Its estrogenic potencymainly depends on its biotransformation fate. The hepatic biotransformation of ZEA in rainbow trout wasinvestigated in this study. Various concentrations of ZEA were separately incubated with the hepaticmicrosomal and post-mitochondrial sub-fractions in the presence of NADPH, and the metabolites wered...
متن کاملMultifocal Stimulation of the Binding of Iodothyronines by Tissues
tration of protein-bound iodine in plasma was decreased, and the binding of the hormones by plasma proteins was increased. The enhanced rate of metabolism of iodothyronines was associated with stimulation of the binding of these hormones by diverse tissues, suggesting the participation of extrahepatic degradative foci in the increased hormonal deiodination observed in vivo. Increased hepatocell...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Biochimica et biophysica acta
دوره 661 2 شماره
صفحات -
تاریخ انتشار 1981