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Research Article Free access | 10.1172/JCI109859

Effect of Secreted Bacteroides Proteases on Human Intestinal Brush Border Hydrolases

Stan P. Riepe, Jeffrey Goldstein, and David H. Alpers

Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110

Find articles by Riepe, S. in: PubMed | Google Scholar

Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110

Find articles by Goldstein, J. in: PubMed | Google Scholar

Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110

Find articles by Alpers, D. in: PubMed | Google Scholar

Published August 1, 1980 - More info

Published in Volume 66, Issue 2 on August 1, 1980
J Clin Invest. 1980;66(2):314–322. https://doi.org/10.1172/JCI109859.
© 1980 The American Society for Clinical Investigation
Published August 1, 1980 - Version history
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Abstract

Selected bacteroides species secreted various amounts of protease and glycosidase into their growth medium. Bacteroides vulgatus, distasonis, and ovatus secreted the most (31-60% of total). The secreted protease was similar in action to the protease within the organism, in that it had a broad pH optimum of 6-9, a Km app. for casein of 0.1 μM, and was inhibited by benzamidine, phenylmethylsulfonyl fluoride, diisopropylfluorophosphate (DIFP), and by an elastase inhibitor, Ac(Ala)3AlaCH2Cl.

Exposure of human brush border preparations to the secreted protease reduced maltase and sucrase activities; the reduction could be prevented by DIFP. In contrast, brush border alkaline phosphatase activity either did not change or increased after exposure to bacterial secretions. >90% inhibition of secreted glycosidase using EDTA and p-chloromercuribenzoic acid did not prevent the reduction of brush border maltase and sucrase activity, suggesting that glucosidases were not likely to be involved in the destruction of brush border enzymes. Moreover, the bacterial proteases caused only a small net release of active maltase or sucrase from the brush border. Most of the loss of activity was due to destruction of the enzyme. Proximal bowel fluid of three patients with overgrowth contained DIFP-inhibitable protease that destroyed sucrase in isolated brush borders. A Bacteroides species was isolated from each sample that secreted protease and destroyed brush border sucrase. We conclude that in bacterial overgrowth syndromes, brush border damage may occur from protease(s) secreted by Bacteroides.

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