注記 |
The effects of amino acids, such as cysteine, cystine, tryptophane, glycocoll, aspartic acid, tyrosine, alanine, leucine and histidine, and also of gelatine-cleavage-products, which contain all amino acids except cysteine, cystine, tyrosine and tryptophane, upon the methods of determining sugar was studied. According to the results of experiments, cysteine, eystine and tryptophane behave as glucose and give more influence than glucose, when taken weight for weight, upon Bang's method. For instance, when 0.3 mg. each of glucose, cystine, cysteine and tryptophane was subjected separately to Bang's method, 0.76, 0.98, 1.02, and 0.77 c.c. of 0.01 N. KIO3 were required respectively. The other amino acids examined have only a little or no effect. Cystine and cysteine show also a remarkable influence upon t h e methods of Polin-Wu, Benedict, Hagedorn, and Shaffer-Hartmann. An example will clearly indicate this relation : A sample, consisting of a mixtnre of 50 mg. each of glucose and Cystine, was subjected to the method§ of Benedict, Folin-Wu, Hagedorn, Shaffer-Hartmann, and Bang, and 73, 59, 76, 88, and 96 mg. of glucose respectively were obtained. Attention should be given to the results thus obtained in the determination of sugar in tissues and biological fluids, since cystine, cysteine, and their derivatives, as determined by many authors, are widely distributed in them.
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