226 P. SOUPART 
enable one to recognize in normal urine more than 4o different ninhydrin-reacting 
substances when the manual procedure is used, and up to 50 or more when the auto- 
matic procedure is applied. Of those 50 ninhydrin-reacting substances 29 form the 
group of well-identified free amino acids, including taurine, asparagine, and glutamine. 
Under the experimental conditions used, ninhydrin-reacting peptides containing up 
to eight amino acids residues should show up as well-defined peaks if their color 
factor allows for it. The remaining unidentified peaks correspond to unknown 
amino acids or to amino acid derivatives or to peptides. They appear as very small 
peaks either because they are excreted in minute amounts or because their color 
Optical density 
Sifluent ml 


ot — Greatimne _ 





Fig. rb. Chronic lymphocytic leukemic patient’s urine. Determination of basic amino acids on 
a 50-cm column (automatic procedure). Free amino acid excretion in this case is normal, both 
qualitatively and quantitatively. 
factor is very low. Many of them are acid-stable. Acid hydrolysis of the urine samples 
produces a marked increase in some of the amino acids of the group of identified 
substances and a minor increase in almost all of the other amino acids of the same 
group. The bulk excretion of combined amino acids is chiefly composed of sub- 
stances such as hippuric acid or phenylacetylglutamine and even some peptides, 
although the presence of the latter in urine is still a matter for debate. WESTALL®, 
and BouLANGER ef al.3. 4 claim that there is evidence for the presence of peptides 
in normal urine, but they must be present in very minute amounts since these 
authors had to process considerable volumes of urine to recognize the presence 
of these peptides. The term “combined amino acids” refers in our opinion to 
substances in which the amino acid is linked to another substance by its amino 
group. We therefore include compounds such as glutamine and asparagine or still 
others, such as tyrosine-O-sulphate? in the group of free amino acids. 
Quantitative composition. Among the 29 free amino acids excreted in normal urine, 
11 have 24-h outputs which range from approx. 10-300 mg. For these amino acids 
References p. 261/262 
