Dataset Information

A Fast and Accurate Method to Identify and Quantify Enzymes in Brush-Border Membranes: In Situ Hydrolysis Followed by Nano LC-MS/MS.

ABSTRACT: A simple method for the identification of brush-border membrane ?-glucosidases is described. The proteins were first solubilized and separated in a gel under native, non-denaturing, conditions. The gel was then incubated in substrate solutions (maltose or sucrose), and the product (glucose) exposed in situ by the oxidation of o-dianisidine, which yields a brown-orange color. Nano-liquid chromatography coupled to mass spectrometry analyses of proteins (nano LC-MS/MS) present in the colored bands excised from the gels, was used to confirm the presence of the enzymes. The stain is inexpensive and the procedure permits testing several substrates in the same gel. Once enzymes are identified, their abundance, relative to that of other proteins in the brush border, can be semi-quantified using nano LC-MS/MS.

SUBMITTER: Brun A

PROVIDER: S-EPMC7189658 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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A Fast and Accurate Method to Identify and Quantify Enzymes in Brush-Border Membranes: In Situ Hydrolysis Followed by Nano LC-MS/MS.

Brun Antonio A Magallanes Melisa E ME Martínez Del Rio Carlos C Barrett-Wilt Gregory A GA Karasov William H WH Caviedes-Vidal Enrique E

Methods and protocols 20200210 1

A simple method for the identification of brush-border membrane α-glucosidases is described. The proteins were first solubilized and separated in a gel under native, non-denaturing, conditions. The gel was then incubated in substrate solutions (maltose or sucrose), and the product (glucose) exposed in situ by the oxidation of o-dianisidine, which yields a brown-orange color. Nano-liquid chromatography coupled to mass spectrometry analyses of proteins (nano LC-MS/MS) present in the colored bands ...[more]

PMID: 32050538

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Project description:Phosphate uptake by rat renal brush-border membrane vesicles was studied under experimental conditions where transmembrane electrical potential (delta psi) could be manipulated. Experiments were performed under initial rate conditions to avoid complications associated with the dissipation of ion gradients. First, phosphate uptake was shown to be strongly affected by the nature of Na+ co-anions, the highest rates of uptake being observed with 100 mM-NaSCN (1.010 +/- 0.086 pmol/5 s per micrograms of protein) and the lowest with 50 mM-Na2SO4 (0.331 +/- 0.046 pmol/5 s per micrograms of protein). Anion substitution studies showed that potency of the effect of the co-anions was in the order thiocyanate greater than nitrate greater than chloride greater than isethionate greater than gluconate greater than sulphate, which correlates with the known permeability of the membrane to these anions and thus to the generation of transmembrane electrical potentials of decreasing magnitude (inside negative). The stimulation by ion-diffusion-induced potential was observed from pH 6.5 to 8.5, indicating that the transport of both monovalent and divalent phosphate was affected. In addition, inside-negative membrane potentials were generated by valinomycin-induced diffusion of K+ from K+-loaded vesicles and showed a 57% stimulation of phosphate uptake, at pH 7.5. Similar experiments with H+-loaded vesicles, in the presence of carbonyl cyanide m-chlorophenylhydrazone gave a 50% stimulation compared with controls. Inside-positive membrane potentials were also induced by reversal of the K+ gradient (outside greater than inside) in the presence of valinomycin and gave 58% inhibition of phosphate uptake. The membrane-potential dependency of phosphate uptake was finally analysed under thermodynamic equilibrium, and a stimulation by inside-negative potential was observed. The transport of phosphate was thus driven against a concentration gradient by a membrane potential, implicating the net transfer of a positive charge during the translocation process. These results indicate a major contribution of electrical potential to phosphate uptake in renal brush-border membranes.

Dataset Information

A Fast and Accurate Method to Identify and Quantify Enzymes in Brush-Border Membranes: In Situ Hydrolysis Followed by Nano LC-MS/MS.

Publications

A Fast and Accurate Method to Identify and Quantify Enzymes in Brush-Border Membranes: In Situ Hydrolysis Followed by Nano LC-MS/MS.

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