Amino Acids

, Volume 6, Issue 3, pp 213–229

Permeability of membranes to amino acids and modified amino acids: Mechanisms involved in translocation

  • A. C. Chakrabarti
Review Article

DOI: 10.1007/BF00813743

Cite this article as:
Chakrabarti, A.C. Amino Acids (1994) 6: 213. doi:10.1007/BF00813743


The amino acid permeability of membranes is of interest because they are one of the key solutes involved in cell function. Membrane permeability coefficients (P) for amino acid classes, including neutral, polar, hydrophobic, and charged species, have been measured and compared using a variety of techniques. Decreasing lipid chain length increased permeability slightly (5-fold), while variations in pH had only minor effects on the permeability coefficients of the amino acids tested in liposomes. Increasing the membrane surface charge increased the permeability of amino acids of the opposite charge, while increasing the cholesterol content decreased membrane permeability. The permeability coefficients for most amino acids tested were surprisingly similar to those previously measured for monovalent cations such as sodium and potassium (approximately 10−12–10−13 cm · s−1). This observation suggests that the permeation rates for the neutral, polar and charged amino acids are controlled by bilayer fluctuations and transient defects, rather than partition coefficients and Born energy barriers. Hydrophobic amino acids were 102 more permeable than the hydrophilic forms, reflecting their increased partition coefficient values.

External pH had dramatic effects on the permeation rates for the modified amino acid lysine methyl ester in response to transmembrane pH gradients. It was established that lysine methyl ester and other modified short peptides permeate rapidly (P = 10−2 cm · s−1) as neutral (deprotonated) molecules. It was also shown that charge distributions dramatically alter permeation rates for modified di-peptides. These results may relate to the movement of peptides through membranes during protein translocation and to the origin of cellular membrane transport on the early Earth.


Amino acid Modified amino acid Permeability Liposome Membrane 





dimyristoyl phosphatidylcholine


egg phosphatidylcholine


large unilamellar vesicle


multilamellar vesicle


planar lipid membrane


small unilamellar vesicle


transmembrane pH gradient

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • A. C. Chakrabarti
    • 1
  1. 1.Section of Molecular and Cellular Biology, Storer HallUniversity of CaliforniaDavisUSA

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