Unbound Amino Acid Concentrations in Human Blood Plasmas

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Abstract
A method of analysis is presented which emphasizes careful and rapid handling of the blood and the amino acid solutions. This involves using nonwettable surfaces during blood collection, low temperature, no change in pH and a rapid dialysis technique. The amino acids are determined on one-dimensional paper chromato-grams developed in salt saturated systems. Recovery studies showed tryptophan was bound to the nondialyzable fraction of plasma at physiological pH whereas the other amino acids were not. Unbound glutamic acid levels were very low in normal plasma compared to previous reports. Levels of amino acids were studied before and immediately, after operation in plasma of patients in good nutritional status and in patients with emaciation. In the former, the amino acid levels dropped an average of 34% after surgery. With the emaciated patients no postoperative drop was seen. Alanine behaved abnormally, in that, relative to the concentrations of the other amino acids, it increased 50% after operation in both groups of patients.