A cycle of deprotonation and reprotonation energizing amino-acid transport?
- 1 January 1975
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 72 (1) , 23-27
- https://doi.org/10.1073/pnas.72.1.23
Abstract
Although lowering the pK2 of neutral amino acids only weakens their concentrative uptake by Ehrlich cells, the same change greatly enhances uptake of diamino acids. This effect does not arise merely from putting the distal amino group in its uncharged form, but depends on an enhanced deprotonation of the alpha-amino group. Parallel effects are seen for the transport system for basic amino acids, for which the assignment of pK values within the membrane is less ambiguous. To explain the paradoxical advantages of having the alpha-amino group protonated yet readily deprotonated, we propose that a proton withdrawn from that group is pumped over an intramembrane interval to energize amino-acid transport.Keywords
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