200 R. G. WESTALL 
TABLE II 
THE FREE AMINO ACIDS OF NORMAL HUMAN ADULT URINE 
Values are expressed in mg/24 h. 
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Bae sos sos 28 8 as 
255 ass Bos Sans ES Sa 
Ros zee ave ES == ree 
BSE BSE BF 38s g5 3: 
8s ASS ARS nS S $ S 
Alanine 40 28 22 24 5- 7I Q- 44 
p-Alanine 6 3 3-10 2-  Q 
a-Aminoadipic acid 8 4 5- 13 o- 13 
fp-Aminoisobutyric acid 13 22 29 6— 37 10— 52 
Aspartic acid <10 8 4 3-2 2— It 
Arginine <10 6 4 O— 14 o- II 
Cystine 10 9 14 6 3-— 33 oO 13 
Glutamic acid <10 13 7- 40 
Glutamine 3} 62 40-103 43-— 88 
Glycine 132 109 104 142 53-200 67-312 
Histidine 216 97 138 128 20-320 79-208 
Isoleucine 18 13 15 10 5— 30 5- 20 
Leucine 14 8 II 9 5- 25 2— 16 
Lysine 19 12 9] 8 o— 48 o— 16 
Methionine 18 6 a 5 5- I1 3-12 
1-Methylhistidine 180 22 73 65 9Q-210 20-155 
3-Methylhistidine 40 65 48 33- 87 30— 69 
Ornithine I 2 Oo- 4 o- II 
Phenylalanine 18 14 13 13 8— 31 6— 41 
Proline <10 
Serine 43 42 37 25- 75 22— O61 
Taurine 156 59 123 87 35-300 27-161 
Threonine 28 17, 2 2— 50 5- 33 
Tyrosine 35 23 19 15 7— 50 Q— 26 
Valine 10 5 10 6 4— 17 o- 30 


in amounts of between 5 and 100 mg/day. Whilst, ornithine and 3-methylhistidine™ 
are also present in similar amounts. 
The complexity of the mixture of amino acids which can be detected in normal 
human urine is such that although all the amino acids in Table II are present so also 
are a large number of others occurring in amounts of 5-10 mg/day or less. Evidence 
for the occurrence of these substances which react with ninhydrin to give a coloured 
product has been provided by workers who have analysed urine concentrates by a 
variety of methods including the use of ion-exchange resins!*-®°, Many of these sub- 
stances are as yet uncharacterized and the number of these substances seems almost 
limitless as new methods lower the threshold of detection. The following amino acids 
have also been detected in urine: f-alanine, a-aminobutyric acid?!, y-aminobutyric 
acid (GABA), a-aminoadipic acid’, a-aminolevulinic acid”, y-guanidinobutyric acid”, 
phenylacetylglutamine?® and sarcosine!8. In addition the following substances, 
not strictly amino acids, give blue-coloured spots with ninhydrin on paper chromato- 
grams and may be often detected in urine: ethanolamine?® 2? and phosphoethanol- 
amine?’S, 29, 
There is apparently no appreciable difference in the amino acid excretion pattern 
References p. 217/219 
