Abstract
Potassium cyanide, in small amount, taken by mouth, produces as marked an increase of the thiocyanate content of the saliva as does an equimolecular amount of potassium thiocyanate, similarly taken. This argues for the physiological conversion of cyanide into thiocyanate.
Evidence is presented to show that potassium cyanide reacts with cystine to yield thicocyanate. This reaction occurs to a slight extent even in neutral solution, but is more pronounced in alkaline solutions of cystine.
The amount of thiocyanate produced is not influenced by varying the amount of potassium cyanide from 0.5 to 4.0 molar equivalents of the cystine, nor by varying the alkalinity between 0.05 and 1.0 m Na2CO3. On the other hand, heating the alkaline cystine solutions, before treating with cyanide, markedly increases their power to form thiocyanate. Apparently the sulfur which is liberated in the alkaline decomposition of cystine (labile S) oxidizes the potassium cyanide to thiocyanate. A smaller portion of the thiocyanate produced under these conditions is present in organic combination as α-amino-β-sulfocyanopropionic acid.
Footnotes
- Received September 23, 1929.
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