Improved determination of D-glucaric acid in urine.
Using a simplex optimization procedure, we have elaborated a sensitive and reliable micromethod for determining D-glucaric acid, based on inhibition of glucuronidase activity by 1,4-D-glucarolactone, produced from D-glucaric acid by heating. The maximum attainable difference between glucuronidase activity in the reaction mixture with and without D-glucaric acid was used as an optimization criterion. From the optimization scheme, 1 mmol/L 4-nitrophenyl-beta-D-glucuronide and pH 5.0 were found to be optimal conditions for determination of D-glucaric acid with this test. In contrast to other similar methods, in which a logarithmic calibration curve is used, we calculate D-glucaric acid with a linear calibration curve by using the Dixon (Biochem. J. 55: 170, 1953) plot. The coefficient of variation for the method (within-run and between-day precision) was from 3.1 to 5.8%. Men excrete more D-glucaric acid than do women per 24 hours, but we saw no sex-related differences in excretion of D-glucaric acid when it was expressed in terms of urinary creatinine.
D005260:Female; D005937:Glucaric Acid / Q000031:analogs & derivatives / Q000494:pharmacology / Q000652:urine*; D005966:Glucuronidase / Q000037:antagonists & inhibitors; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007783:Lactones / Q000494:pharmacology; D008297:Male; D012737:Sex Factors; D013400:Sugar Acids / Q000652:urine*
D007783:Lactones; D013400:Sugar Acids; C009194:saccharolactone; D005966:Glucuronidase; D005937:Glucaric Acid