Abstract
As a contribution to the understanding of the thermodynamic state of single salts in living systems, the activity coefficients of KCl were determined in concentrated bovine serum albumin (BSA) solutions. The concentration range studied was 0.01 to 0.5 M KCl and zero to 18% wt BSA, thus amply covering physiological conditions. The activity coefficients of the salt were measured using the EMF method with ion exchange membrane electrodes. Keeping the salt concentration constant, the activity coefficients of the salt decrease linearly with protein concentration, the effect being more pronounced for low salt content. The maximal deviations of the activity coefficients with respect to those in pure salt solution amount to ca. 40% for 0.01 M KCl and 18% wt BSA. The results were interpreted on the assumption of the superposition of three effects i.e. water bound to BSA molecules as “non-solvent” water, specific Cl− ion binding and the electrostatic interactions of the polyions with the salt ions. In view of the results it can be concluded that only a small portion of simple intracellular ions are bound, based on the assumption that the cytoplasm of living cells may be regarded as a concentrated protein-salt solution.
Similar content being viewed by others
References
Amberg CH (1957) Heats of adsorption of water on bovine serum albumin. J Am Chem Soc 79:3980–3984
Baker HP, Saroff HA (1965) Binding of sodium ions to β-lactoglobulin. Biochemistry 4:1670–1677
Bull HB, Breese K (1968) Protein hydration I. Binding sites. Arch Biochem Biophys 128:488–496
Carr CW (1952) Studies on the binding of small ions in protein solutions with the use of membrane electrodes I. The binding of the chloride ion and other inorganic anions in solution of serum albumin. Arch Biochem Biophys 40: 286–294
Carr CW (1968) Applications of membrane electrodes. Ann NY Acad Sci 148:180–190
Carrol WR, Callanan MJ, Saroff HA (1959) Physical and chemical properties of protamine from the sperm of salmon (Oncorhynchus tschawytscha) II. Anion binding characteristics. J Biol Chem 234:2314–2316
Cox DJ, Schumaker VN (1961) The preferential hydratation of proteins in concentrated salt solutions I. Sedimentation studies. J Am Chem Soc 83:2433–2438
Giese AC (1973) Cell physiology, 4th edn. WB Saunders, Philadelphia, p 56
Grigera JR, Mascarenhas S (1978) A model for NMR, dielectric relaxation and electret behavior of bound water in proteins. Studia Biophysica 73:19–24
Hale KD, Govindan KP (1969) Bi-ionic potentials with sulfonic and phosphonic acid cation-exchange membranes. J Electrochem Soc 116:1373–1381
Hasl G, Pauly H (1973) Schmelzverhalten und kalorische Eigenschaften einer Mischung von Rinderserumalbumin, Kochsalz und Wasser. Biophysik 10:125–136
Hinz HJ (1983) Thermodynamics of protein-ligand interactions: Calorimetric approaches. Annu Rev Biophys Bioeng 12:285–317
Kwak JCT (1973) Mean activity coefficients for the simple electrolyte in aqueous mixtures of polyelectrolyte and simple electrolyte. The system sodium polystyrenesulfonatesodium chloride. J Phys Chem 77:2790–2793
Kwak JCT, O'Brien MC, MacLean DA (1975) Mean activity coefficients for the simple electrolyte in Aqueous mixtures of polyelectrolyte and simple electrolyte. The system potassium chloride-potassium poly(styrenesulfonate), magnesium chloride-magnesium poly(styrenesulfonate) and calcium chloride-calcium poly(styrenesulfonate). J Phys Chem 79:2381–2386
Kwak JCT, Morrison NJ, Spiro EJ, Iwasa K (1976) Mean activity coefficients for the simple electrolyte in aqueous mixtures of polyelectrolyte and simple electrolyte. The mixed counterion system Na+, Ca2+, Cl−, polystyrenesulfonate. J Phys Chem 80:2753–2761
Lewis MS, Saroff HA (1957) The binding of ions to the muscle protein. Measurements of the binding of potassium and sodium ions to myosin A, myosin B and actin. J Am Chem Soc 79:2112–2117
Loeb GI, Saroff HA (1964) Chloride- and hydrogen-ion binding to ribonuclease. Biochemistry 3:1819–1826
Lyons JW, Kotin L (1965) Ion binding in polyelectrolyte systems with or without added salt. J Am Chem Soc 87: 1670–1678
Nossal R, Klinka CJ, Chen SH (1986) SANS studies of concentrated protein solutions I. Bovine serum albumin. Biopolymers 25:1157–1175
Oosawa F, Imai N, Kagawa I (1954) Theory of strong polyelectrolyte solutions I. Coiled macro ions. J Polym Sci 13: 93–111
Parsons R (1959) Handbook of electrochemical constants. Butterworths, London, p 20
Pauly H (1973) Über den physikalisch-chemischen Zustand des Wassers und der Elektrolyte in der lebenden Zelle. Biophysik 10:7–32
Peters Th Jr (1975) Serum albumin. In: Putnam FW (ed) The plasma proteins, 2nd edn. Academic Press, New York, pp 133–181
Peters Th Jr (1985) Serum albumin. Adv Protein Chem 37: 161–245
Pfister H (1970) Mittlerer Aktivitätskoeffizient von KCl in Zytoplasma-Fraktionen aus Kalbsleberzellen. Z Naturforsch 25:1130–1136
Pfister H (1971) Das chemische Potential von Kaliumchlorid in konzentrierten Proteinlösungen. Ein Beitrag zum Verständnis des thermodynamischen Zustandes des Zytoplasmas. Thesis, Universität Erlangen-Nürnberg, FRG
Pfister H, Pauly H (1969) Einfluß von Diffusionspotentialen auf Membranpotential und Ionenaktivitätsmessungen in biologischen Systemen am Beispiel von KCl-Rinderserumalbumin-Lösungen. Biophysik 6:94–112
Pfister H, Pauly H (1972) Chemical potential of KCl and its ion constituents in concentrated protein salt solutions. J Polym Sci Part C 39:179–189
Reboiras MD, Pfister H, Pauly H (1978) Activity coefficients of salts in highly concentrated protein solutions. I. Alkali chlorides in isoionic bovine serum albumin solutions. Biophys Chem 9:37–46
Reboiras MD, Pfister H, Pauly H (1986) Activity coefficients of salts in highly concentrated protein solutions. II. Potassium salts in isoionic bovine serum albumin solutions. Biophys Chem 24:249–257
Rosen D (1963) Dielectric properties of protein powders with adsorbed water. Trans Faraday Soc 59:2178–2191
Saroff HA, Carrol WR (1962) The binding of chloride and sulfate ions to ribonuclease. J Biol Chem 237:3384–3387
Saroff HA, Lewis MS (1963) The binding of calcium ions to serum albumin. J Phys Chem 67:1211–1216
Scatchard G (1953) Ion exchanger electrodes. J Am Chem Soc 75:2883–2887
Scatchard G, Scheinberg IH, Armstrong SH Jr (1950a) Physical chemistry of protein solutions IV. The combination of human-serum albumin with chloride ion. J Am Chem Soc 72:535–540
Scatchard G, Scheinberg IH, Armstrong SH Jr (1950b) Physical chemistry of protein solutions V. The combination of human serum albumin with thiocyanate ion. J Am Chem Soc 72:540–546
Scatchard G, Coleman JS, Shen AL (1957) Physical chemistry of protein solutions VII. The binding of some small anions to serum albumin. J Am Chem Soc 79:12–19
Scatchard G, Wu YV, Shen AL (1959) Physical chemistry of protein solutions X. The binding of small anions by serum albumin. J Am Chem Soc 81:6104–6109
Schmid WH (1976) Der mittlere Aktivitätskoeffizient von einfachen Kaliumsalzen in konzentrierten Rinderhämoglobinlösungen. Thesis, Universität Erlangen-Nürnberg, FRG
Sollner K (1968) Membrane electrodes. Ann NY Acad Sci 148:154–179
Steinhardt J, Reynolds JA (1969) Multiple equilibria in proteins. Academic Press, New York
Tretter N (1975) Der Aktivitätskoeffizient von NaCl in hochkonzentrierten Hämoglobinlösungen und in Erythrozyten. Thesis, Universität Erlangen-Nürnberg, FRG
Tsien RY (1983) Intracellular measurements of ion activities. Annu Rev Biophys Bioeng 12:91–116
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Ocon, P., Acerete, C. & Reboiras, M.D. Activity coefficients of KCl in highly concentrated protein solutions. Eur Biophys J 14, 477–484 (1987). https://doi.org/10.1007/BF00293257
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00293257