Conjugated estrogens IV. Separation of urinary estrogens by gel-filtration and the effect of endogenous inhibitor on the rate and extent of hydrolysis by β-glucuronidase

Kushinsky, Stanley; Otterness, Ivan G.

doi:10.1016/0039-128x(64)90039-x

Cited by 26 publications

(6 citation statements)

References 21 publications

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“…It is clear from earlier reports [1,3,8,14,20,21] as well as from the data presented here that there are inhibitors of ß-glucuronidase in urine. It is clear also that there are variations in the properties of the inhibitors in different specimens of urine and when urine is main tained under different conditions.…”

Section: Discussionsupporting

confidence: 64%

“…General: Gel-filtration of urine, measurement of radioactivity and related procedures were carried out as described earlier [14,16]. Measurement of pH was done with a Radiometer Model TTT-1 pH meter.…”

Section: Experiments and Resultsmentioning

confidence: 99%

“…In a recent publication, data were presented showing that an inhibitor of ß-glucuronidase present in urine appears to selectively inhibit the hydrolysis of some estrogen glucuronosides [14]. The endogenous inhibitor (1,4-saccharolactone) previously had been separated from the estrogens by gel-filtration using the method of Beling [3] and then added back in the concentration reported by Marsh to be present in urine [20,21].…”

Section: Introductionmentioning

confidence: 99%

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Urinary Inhibitors of ß-Glucuronidase

Kushinsky¹,

Chen²

1967

Enzymol Biol Clin

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A study has been made of some of the properties of the inhibitors of ß-glucuronidase in human urine. The inhibitory properties were determined by comparing the effect on the activity of ß-glucuronidase of urine pre-treated in many ways with that of a control containing no urine. A significant though variable fraction of the inhibition is caused by rapidly hydrolyzing competitive substrates of normal dietary or therapeutic origin. Other inhibitors such as 1,4-saccharolactone probably account for a substantially greater fraction of the inhibition than do the competitive substrates. The inhibition by 1,4-saccharolactone is a function of the pH, temperature and time of equilibration of the medium. Saccharolactone can he separated from the conjugated estrogens in urine by gel-filtration on Sephadex. The extent which non-substrate, competitive inhibitors or competitive substrates reduce the activity of ß-glucuronidase is a function of the inhibitor constant (K(I)) or the Michaelis constant (Km) respectively and the concentrations of these substances. On prolonged standing the activity of ß-glucuronidase is reduced more in the presence of urine than in the absence of urine. This phenomenon probably is due at least partially to the slow formation of saccharolactone from endogenous saccharic acid in urine.

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Section: Discussionsupporting

confidence: 64%

Section: Experiments and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Urinary Inhibitors of ß-Glucuronidase

Kushinsky¹,

Chen²

1967

Enzymol Biol Clin

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“…Steroid conjugates have been isolated from biological fluids by extraction with organic solvents ( l ) , extraction as pyridinium salts into chloroform (3), gel atration (4- 7), and adsorption on charcoal or alumina-diatomaceous earth1 (2, 8). Group separations of steroid sulfates and glucuronides have been accomplished by adsorption chromatography on alumina (9,10) or diatomaceous earth (ll), paper chromatography ( 12), thin-layer chromatography (13), and ion exchange (14).…”

mentioning

confidence: 99%

“…Group separations of steroid sulfates and glucuronides have been accomplished by adsorption chromatography on alumina (9,10) or diatomaceous earth (ll), paper chromatography ( 12), thin-layer chromatography (13), and ion exchange (14). Steroid sulfates have been separated by partition chromatography on diatomaceous earth (15) or on methylated dextran gel (16), by ion exchange (14), and steroid glucuronides have been partially separated by gel filtration on dextran gel (7).…”

mentioning

confidence: 99%