Abstract
In the present study we have determined the kinetics of 3-deoxy-3-fluoro-D-glucose (3-FG) as a substrate for the aldose reductase reaction in vitro. In addition, we compared the 3-deoxy-3-fluoro-sorbitol (3-FS) production rates from 3-FG in the intact lens using 19F NMR with conventional aldose reductase determinations in extracts from the same lenses. The affinity of in vitro aldose reductase for 3-FG was approximately 20 times greater (9.3 mM) than that for glucose (188 mM). An excellent correlation between the rate of 3-FS production in the intact canine lens, determined with 19F NMR, and extracted aldose reductase activity was observed. The relatively high affinity of aldose reductase for 3-FG and the correlation of 3-FS production with enzyme activity in the intact lens suggests that 3-FS production from 3-FG detected by 19F NMR could provide an accurate noninvasive determination of aldose reductase activity in the eye lens.
Highlights
In the present study we have determinedthe kinetics of 3-deoxy-3-fluoro-~-g~uco(3s-eFG)as a substrate for the aldose reductase reaction in vitro.In addition, we compared the 3-deoxy-3-fluoro-sorbitol(3-FS) production rates from 3-FG in the intact lens using ‘‘F NMR with conventional aldose reductase determinations in extracts from the same lenses
While the causes of diabetic complications remain unknown, evidence suggests that the enzyme aldose reductase provides a common biochemical link in the pathogenesis of various diabetic complications including cataract, keratopathy, retinopathy, neuropathy, and possibly nephropathy (15 ) .For example, experimental sugar cataracts rapidly form in a variety of diabetic and galactose-fed animals [6]
Production was observed when lenses were incubated in medium containing glucose levels representative of those observed in diabetes (-25 mM)
Summary
Vol 266,No 31,Issue of November 5,pp. 20970-20975,1991 Printed in U.S.A. 19FNMR Quantitation of Lens Aldose ReductaseActivity Using 3-Deoxy-3-fluoro-~-g~ucose*. While the causes of diabetic complications remain unknown, evidence suggests that the enzyme aldose reductase provides a common biochemical link in the pathogenesis of various diabetic complications including cataract, keratopathy, retinopathy, neuropathy, and possibly nephropathy (15 ) .For example, experimental sugar cataracts rapidly form in a variety of diabetic and galactose-fed animals [6] Their rate of formation is proportional to the lenticular levels of aldose reductase and theirformation is inhibited by aldose reductase inhibitors. We report the i n vitro kinetic properties of aldose reductase with 3-FG as substrate, and compare the rate of production of 3-FS in the intact lens, monitored by ”F NMR, with conventional enzyme assays of aldose reductase activity on the same lens
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