Methodological Problems in the Determination of Total and Free Plasma Tryptophan

  • G. Curzon
Part of the Journal of Neural Transmission book series (NEURAL SUPPL, volume 15)


There has been much discussion of the utility of plasma concentrations of tryptophan (total and free) and of amino acids competing with tryptophan for transport to the brain as predictors of brain tryptophan concentration. This issue now may be attaining resolution (Curzon, this volume; Green, 1978; Wurtman, this volume). It appears that large changes of competing amino acid concentrations (e.g. following food intake) have important effects on brain tryptophan while in other circumstances changes of plasma free tryptophan concentration (e.g. when drugs or physiological changes alter the binding of plasma tryptophan to albumin) also have considerable effects. In the past, different groups of workers have focused their attention on experimental situations in which one or other of the above influences were predominant and this has given an impression of a greater polarization of attitudes than was perhaps justified. Also much confusion has resulted from methodological problems and artefactual changes. The following note on methods for the determination of plasma tryptophan (total and free) and non-esterified fatty acid (NEFA) may therefore be helpful.


Ferric Chloride Great Polarization Tryptophan Concentration Plasma Tryptophan Unesterified Fatty Acid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Baumann, P., Perey, M.: The analysis of free tryptophan in human blood with the ultrafiltrator: a comparison with other methods. Clin. Chim. Acta 76, 223–231 (1977).PubMedCrossRefGoogle Scholar
  2. Bender, D. A., Boulton, A. P., Coulson, W. F.: A simple method for the study of tryptophan binding to serum albumin by small scale equilibrium dialysis: application to animals and human studies. Biochem. Soc. Trans. 3, 193–194 (1975).PubMedGoogle Scholar
  3. Bloxam, D. L., Warren, W. H.: Error in the determination of tryptophan by the method of Denckla and Dewey. A revised procedure. Anal. Biochem. 60, 621–625 (1974).CrossRefGoogle Scholar
  4. Bloxam, D. L., Warren, W. H., White, P. J.: Involvement of liver in the regulation of tryptophan availability: possible role in the response of liver and brain to starvation. Life Sci. 15, 1443–1445 (1974).PubMedCrossRefGoogle Scholar
  5. Bloxam, D. L., Hutson, P. H., Curzon, G.: A simple apparatus for ultrafiltration of small volumes: application to the measurement of free and albumin-bound tryptophan in plasma. Anal. Biochem. 83, 130–142 (1977).PubMedCrossRefGoogle Scholar
  6. Curzon, G.: Relationships between plasma, CSF and brain tryptophan. J. Neural Transm., Suppl. 15, pp. 81–92. Wien-New York: Springer. 1979.Google Scholar
  7. Curzon, G., Kantamaneni, B. D.: Fluorometric determination of plasma unesterified fatty acid. Clin. Chim. Acta 76, 289–292 (1977).PubMedCrossRefGoogle Scholar
  8. Denckla, W. D., Dewey, H. K.: The determination of tryptophan in plasma, liver and urine. J. Lab. Clin. Med. 69, 160–169 (1967).PubMedGoogle Scholar
  9. Dole, V. P.: A relation between non-esterified fatty acids in plasma and the metabolism of glucose. J. Clin. Invest. 35, 150–154 (1956).PubMedCrossRefGoogle Scholar
  10. Eccleston, E. G.: A method for the determination of free and total acid-soluble tryptophan using an ultrafiltration technique. Clin. Chim. Acta 48, 269–272 (1973).PubMedCrossRefGoogle Scholar
  11. Elpbick, M. C: Modified colorimetric ultramicro method for estimating NEFA in serum. J. Clin. Path. 21, 567–570 (1968).CrossRefGoogle Scholar
  12. Flentge, F., Venema, K., Korf, J.; Automated assay of tryptophan at the nanogram level: determination of tryptophan in cerebrospinal fluid and of total and non-protein bound tryptophan in serum. Biochem. Med. 11, 231–241 (1974).CrossRefGoogle Scholar
  13. Gentil, V., Lader, M. H., Kantamaneni, B. D., Curzon, G.: Effects of adrenaline injection on human plasma tryptophan and non-esterified fatty acids. Clin. Sci. Mol. Med. 53, 227–232 (1977).PubMedGoogle Scholar
  14. Green, A. R.: The effects of dietary tryptophan and its peripheral metabolism on brain 5-HT synthesis and function. Essays in Neurochemistry and Neuropharmacology 3, 103–127 (1978).PubMedGoogle Scholar
  15. Hutson, P. H., Knott, P. J., Curzon, G.: Control of brain tryptophan concentration in rats on a high fat diet. Nature 262, 142–143 (1976).PubMedCrossRefGoogle Scholar
  16. Knott, P. J., Curzon, G.: Free tryptophan in plasma and brain tryptophan metabolism. Nature 239, 452–453 (1972).PubMedCrossRefGoogle Scholar
  17. Laurell, S., Tibbling, H.: Colorimetric micro determination of free fatty acids in plasma. Clin. Chim. Acta 16, 57–62 (1967).PubMedCrossRefGoogle Scholar
  18. Lehmann, J.: Light-a source of error in the fluorometric determination of tryptophan. Scand. J. Clin. Lab. Invest. 28, 49–55 (1971).PubMedCrossRefGoogle Scholar
  19. Madras, B. K., Cohen, E. L., Messing, R. L., Larin, F., Munro, H. N., Wurtman, R. J.: Relevance of free tryptophan in serum to tissue tryptophan concentrations. Metabolism 23, 1107–1116 (1974).PubMedCrossRefGoogle Scholar
  20. McMenamy, R. H.: Binding of indole analogues to human serum albumin. Effects of fatty acids. J. biol. Chem. 24, 4235–4243 (1965).Google Scholar
  21. Sullivan, P. A., Murnaghan, D., Callaghan, N., Kantamaneni, B. D., Curzon, G.: Cerebral transmitter precursors and metabolites in advanced renal disease. J. Neurol. Neurosurg. Psychiat. 41, 581–588 (1978).PubMedCrossRefGoogle Scholar
  22. Williamson, J., Scott-Finnigan, T. J.: Phospolipid interference and other variables in analysis of non-esterified fatty acids by copper soap formation. Clin. Chim. Acta 57, 175–179 (1974).PubMedCrossRefGoogle Scholar
  23. Wood, K., Swade, C, Harwood, J., Eccleston, E., Bishop, M., Coppen, A.: Comparison of methods for the determination of total and free tryptophan in plasma. Clin. Chim. Acta 80, 299–303 (1977).PubMedCrossRefGoogle Scholar
  24. Wurtman, R. J., Pardridge, W. M.: Summary: Circulating tryptophan, brain tryptophan, and psychiatric disease. J. Neural Transm., Suppl. 15, pp. 227–236. Wien-New York: Springer. 1979.Google Scholar

Copyright information

© Springer-Verlag Wien 1979

Authors and Affiliations

  • G. Curzon
    • 1
  1. 1.Department of NeurochemistryInstitute of NeurologyLondonUK

Personalised recommendations