pH-Dependent Hydrolysis of 4,4′-Diformamidodiphenylsulfone

1971 ◽  
Vol 60 (4) ◽  
pp. 606-608 ◽  
Author(s):  
L.C. Garg
Keyword(s):  
Ph Dependent ◽  
Hydrolysis Of

Modeling the pH dependent hydrolysis of VX for aqueous releases

2009 ◽  
Vol 170 (1) ◽  
pp. 72-78 ◽  
Author(s):  
J.A. Cragan ◽  
M.C. Ward ◽  
C.B. Mueller
Keyword(s):  
Ph Dependent ◽  
Hydrolysis Of

pH-dependent hydrolysis of acetylcholine: Consequences for non-neuronal acetylcholine

2015 ◽  
Vol 29 (1) ◽  
pp. 27-30 ◽  
Author(s):  
Ignaz Wessler ◽  
Rosmarie Michel-Schmidt ◽  
Charles James Kirkpatrick
Keyword(s):  
Ph Dependent ◽  
Hydrolysis Of

scholarly journals pH-dependent spontaneous hydrolysis rather than gut bacterial metabolism reduces levels of the ADHD treatment, Methylphenidate

2020 ◽  
Author(s):  
Julia Aresti-Sanz ◽  
Walid Maho ◽  
Rob Rodrigues Pereira ◽  
Hjalmar Permentier ◽  
Sahar El Aidy
Keyword(s):  
Intestinal Bacteria ◽  
Bacterial Metabolism ◽  
Spontaneous Hydrolysis ◽  
Adhd Treatment ◽  
High Interindividual Variability ◽  
Carboxylesterase 1 ◽  
Ph Dependent ◽  
Small Intestinal ◽  
Hydrolysis Of

AbstractMethylphenidate is absorbed in the small intestine. The drug is known to have low bioavailability and a high interindividual variability in terms of response to the treatment. Gut microbiota has been shown to reduce the bioavailability of a wide variety of orally administered drugs. Here, we tested the ability of small intestinal bacteria to metabolize methylphenidate. In silico analysis identified several small intestinal bacteria to harbor homologues of the human carboxylesterase 1 enzyme responsible for the hydrolysis of methylphenidate in the liver. Despite our initial results hinting towards possible bacterial hydrolysis of the drug, up to 60% of methylphenidate was spontaneously hydrolyzed in the absence of bacteria and this hydrolysis was pH-dependent. Overall, the study shows that pH-dependent spontaneous hydrolysis rather than gut bacterial metabolism reduces levels of methylphenidate and suggest a role of the luminal pH in the bioavailability of the drug.

Intralysosomal hydrolysis of thyroglobulin

1983 ◽  
Vol 103 (1) ◽  
pp. 62-67 ◽  
Author(s):  
Francis Fouchier ◽  
John L. Mego ◽  
Josseline Dang ◽  
Claude Simon
Keyword(s):  
Proteolytic Activity ◽  
Iodine Content ◽  
Lysosomal Proteinases ◽  
The Mean ◽  
Hydrolytic Process ◽  
Ph Dependent ◽  
Hydrolysis Of

Abstract. Degradations of recently (1 h) iodinated thyroglobulin (Tg) and of Tg iodinated for 48 h (fully iodinated molecule) inside thyroid phagolysosomes have been measured in vitro, at different pH, in basal (lysosomes from normal rats) and stimulated (lysosomes from TSH-treated rats) conditions. In basal conditions, recently iodinated Tg was shown to be preferentially degraded at pH 5 but not at pH 8. Mercaptoethanol (ME) was found to preferentially stimulate the degradation of 48 h-iodinated Tg at pH 5 but not at pH 8. In stimulated conditions and in the presence of ME, no preferential hydrolysis of recently iodinated Tg was observed, whatever the pH. Since the degradation of Tg and its stimulation by ME are known to depend on the mean iodine content of the molecule, it was concluded that: 1) the recently iodinated Tg population contains both poorly and fully iodinated molecules, the degradations of which are faster or similar to that of 48 h-iodinated Tg, respectively, 2) among thyroid phagolysosomes, only those which exhibit a pH-dependent proteolytic activity contain poorly iodinated molecules while others, which are functional at either pH, contain solely fully iodinated molecules (1 and 48 h labelled), 3) reduction of the disulphide bridges of fully iodinated Tg, mediated by ME and probably a lysosomal transhydrogenase, is a prerequisite for its optimal degradation by lysosomal proteinases, 4) in addition, TSH, which preferentially stimulates the degradation of fully iodinated Tg, was concluded to interfere directly upon the intralysosomal hydrolytic process, independently of its effect upon Tg endocytosis. This effect of TSH, similar and additive to that of ME suggests that the hormone might activate a lysosomal transhydrogenase.

Folate binding and hydrolysis by pig intestinal brush-border membranes

1986 ◽  
Vol 251 (4) ◽  
pp. G481-G486 ◽  
Author(s):  
A. M. Reisenauer ◽  
C. J. Chandler ◽  
C. H. Halsted
Keyword(s):  
Brush Border ◽  
Metal Ion ◽  
Binding Capacity ◽  
Hydrolytic Enzyme ◽  
Jejunal Mucosa ◽  
Intestinal Brush Border Membrane ◽  
Intestinal Brush Border ◽  
Ph Dependent ◽  
Hydrolysis Of ◽  
Binding Component

The intestinal absorption of dietary polyglutamyl folate involves hydrolysis, binding, and transport at the brush-border surface of the enterocyte. We studied the binding of [3H]folic acid ([3H]PteGlu) and the hydrolysis of [14C]pteroyltriglutamate ([14C]PteGlu3) by use of brush-border vesicles prepared from pig jejunal mucosa. [3H] PteGlu associated with the vesicles was not affected by increasing the osmolarity of the incubation solution, verifying that the experiments describe binding and not transport of PteGlu. The binding of [3H]PteGlu was saturable (Kd = 0.08 microM) and pH dependent with maximal binding at pH 5.2. Binding was competitively inhibited by PteGlu3 (Ki = 0.25 microM) and 5-methyltetrahydrofolate (Ki = 0.8 microM) but was not affected by components of the PteGlu molecule. ZnCl2, MgCl2, and MnCl2 enhanced the binding capacity but not the affinity of the binding component for PteGlu. We distinguished the processes of folate binding and hydrolysis by demonstrating differences in metal ion requirements and susceptibilities to various inhibitors. In addition, the binding component and the hydrolytic enzyme had distinct affinities for PteGlu (Ki = 45 microM for PteGlu3 hydrolysis). These data demonstrate pH-dependent, specific, and saturable binding of PteGlu to the intestinal brush-border membrane and suggest that the binding component is separate from the hydrolytic enzyme.

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