Plasma tryptophan binding to albumin in unipolar depressives.

The equilibrium binding constants of the interaction of tryptophan with albumin have been determined in plasma samples from both controls and patients suffering from affective disorders. The data corresponded with literature values for both the albumin concentration in plasma and the equilibrium constant for tryptophan binding to albumin. No differences in the equilibrium constants were detected between patients and controls but a small increase in the albumin concentration was noted in the depressives. It was agreed that this rise would be inadequate to lead to a significant effect on free tryptophan levels. Non-esterified fatty acid analysis indicated no differences between patient groups.