Sensitization of D-glucuronic acid transport system of E. coli to protein group reagents in presence of substrate or absence of energy source

AbstractIrinotecan inhibits cell proliferation and thus is used for the primary treatment of colorectal cancer. Metabolism of irinotecan involves incorporation of β-glucuronic acid to facilitate excretion. During transit of the glucuronidated product through the gastrointestinal tract, an induced upregulation of gut microbial β-glucuronidase (GUS) activity may cause severe diarrhea and thus force many patients to stop treatment. We herein report the development of uronic isofagomine (UIFG) derivatives that act as general, potent inhibitors of bacterial GUSs, especially those of Escherichia coli and Clostridium perfringens. The best inhibitor, C6-nonyl UIFG, is 23,300-fold more selective for E. coli GUS than for human GUS (Ki = 0.0045 and 105 μM, respectively). Structural evidence indicated that the loss of coordinated water molecules, with the consequent increase in entropy, contributes to the high affinity and selectivity for bacterial GUSs. The inhibitors also effectively reduced irinotecan-induced diarrhea in mice without damaging intestinal epithelial cells.

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Reconstitution into proteoliposomes and partial purification of the Golgi apparatus membrane UDP-galactose, UDP-xylose, and UDP-glucuronic acid transport activities.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)48465-7 ◽

1992 ◽

Vol 267 (1) ◽

pp. 103-107

Author(s):

M E Milla ◽

C A Clairmont ◽

C B Hirschberg

Keyword(s):

Golgi Apparatus ◽

Glucuronic Acid ◽

Partial Purification ◽

Acid Transport

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Osmotic Regulation of ATA2 mRNA Expression and Amino Acid Transport System A Activity

Biochemical and Biophysical Research Communications ◽

10.1006/bbrc.2001.4729 ◽

2001 ◽

Vol 283 (1) ◽

pp. 174-178 ◽

Cited By ~ 38

Author(s):

Roberta R. Alfieri ◽

Pier-Giorgio Petronini ◽

Mara A. Bonelli ◽

Alessandro E. Caccamo ◽

Andrea Cavazzoni ◽

...

Keyword(s):

Amino Acid ◽

Mrna Expression ◽

Transport System ◽

Amino Acid Transport ◽

Osmotic Regulation ◽

Acid Transport ◽

Amino Acid Transport System ◽

System A

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Inhibition of Amino Acid Transport in Rabbit Intestine by p-Chloromercuriphenyl Sulfonic Acid

The Journal of General Physiology ◽

10.1085/jgp.62.2.131 ◽

1973 ◽

Vol 62 (2) ◽

pp. 131-146 ◽

Cited By ~ 42

Author(s):

John F. Schaeffer ◽

Robert L. Preston ◽

Peter F. Curran

Keyword(s):

Transport System ◽

Conformational Changes ◽

Marked Reduction ◽

Sulfhydryl Group ◽

Major Effect ◽

Acid Transport ◽

Michaelis Constant ◽

Saturation Kinetics ◽

Rabbit Intestine ◽

Transport Site

Influx of phenylalanine across the brush border of rabbit intestine is markedly reduced by treatment with 5 mM p-chloromercuriphenyl sulfonate (PCMBS). The effect is rapidly and completely reversed by dithiothreitol. Phenylalanine influx into PCMBS-treated tissue can be competitively inhibited by other neutral amino acids and follows saturation kinetics. PCMBS causes an increase in the apparent Michaelis constant from the value observed in control tissue but does not alter the maximal influx significantly. Treatment of the tissue with PCMBS leads to a significant reduction in the Na-sensitivity of the transport, and a number of results indicate that the major effect of the reagent is to cause a marked reduction in the affinity of the transport system for Na. The transport system can be partially protected against reaction with PCMBS by phenylalanine and tryptophan but not by methionine or norleucine. The results suggest that PCMBS reacts with a sulfhydryl group in the region of the transport site and may alter conformational changes associated with the binding of substrates.

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