CONJUGATED AMINO ACIDS IN PLASMA OF PATIENTS WITH UREMIA*

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Abstract
Free alpha amino N in deproteinized plasma from patients with uremia was approximately normal. Hydrolysis with 6N HC1 produced a mean increase amounting to 3.0 mg/100 ml, as determined by the manometric ninhydrin method, in contrast with a mean increase of 0.6 mg/100 ml in normal subjects. Chromatographic separation with a preparative ion-exchange column yielded fractions which were analyzed for ninhydrin color before and after hydrolysis. Three peaks appeared after hydrolysis, with little or no color prior to hydrolysis. Other appropriate tests showed that one peak contained phenylacetylglutamine, a substance present in normal urine but not previously identified in blood. Another peak, not retained on the acidic resin, was eluted near column volume with the blood glucose. It could not be resolved further by chromatography on a basic resin or on paper. After hydrolysis aspartic acid, glutamic acid, threonine, serine, glycine, and alanine were identified. The 3d peak displayed properties similar to those of the 2d.