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Proton Flux Measurements from Tissues in Buffered Solution


Arif, I and Newman, IA and Keenlyside, NS, Proton Flux Measurements from Tissues in Buffered Solution, Plant, Cell & Environment, 18, (11) pp. 1319-1324. ISSN 0140-7791 (1995) [Refereed Article]

DOI: doi:10.1111/j.1365-3040.1995.tb00191.x


Proton movement across plant cell membranes is part of many important physiological processes. The net proton flux to or from tissues can be determined non‐invasively by measuring the proton electrochemical potential gradient in the adjacent solution. In buffered solution, some of the protons crossing the tissue boundary diffuse as proto‐nated buffer whose flux is not included in the flux calculated from the proton (hydrogen ion) electrochemical gradient. In this theoretical paper, it is shown how experimenters can calculate the protonated buffer flux from the measured proton flux in solution. The ratio of these two components of total proton flux depends on the pH of the solution and on the concentration and pK of the buffer. For a given concentration of a buffer which has a single pK, the flux ratio rises with pH when the solution pH is lower than the buffer pK. The slope is about 2 on a log10 scale. As the pH increases above the pK, the flux ratio levels off to approach its maximum. With mixed buffers, or one having two or more pK values, the flux ratios are additive: each buffer acts independently based on its concentration and its pK value. Unbuffered solutions always have the buffering effects of water itself and also of carbonates due to carbon dioxide dissolved from the atmosphere. In unbuffered solutions at pH 6, the flux carried by water and carbonate is about 1 % of the measured proton flux. This validates measurements of proton flux from tissues, made by a number of workers, in unbuffered solutions below pH 6. Copyright © 1995, Wiley Blackwell. All rights reserved

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Medical and biological physics
Research Field:Biological physics
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the environmental sciences
UTAS Author:Arif, I (Mr Idam Arif)
UTAS Author:Newman, IA (Dr Ian Newman)
UTAS Author:Keenlyside, NS (Mr Noel Sebastian Keenlyside)
ID Code:3443
Year Published:1995
Web of Science® Times Cited:34
Deposited By:Physics
Deposited On:1995-08-01
Last Modified:2011-08-22

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