Cystine metabolism. II

Abstract

In our last communication 1 we stressed the data bearing on the equilibrium Cystine Cystein and gave a general outline of the program of the investigation of cystine metabolism. The twelve preparations of cystine and cystein therein described have been fed to rabbits and the urines corresponding to them have been analyzed. The analysis of the large mass of data is not yet complete. In this communication we will discuss the fate of cystine and cystein as such and one of the derivatives and compare our results with data of other workers, e. g., Wohlgemuth 2 , Lewis and Root 3 and Schmidt and Clark 4 . All the figures have been recast so as to give the increase in sulfur in mg. following the administration of cystine sulfur, as cystine or its derivative.

The total sulfur varies with the food and is reasonably constant. It is highest on the carrot diet, about 50 mg. per kilo, and lowest on the milk diet, 8 to 16 mg. per kilo. The sulfur partition of the control periods bears no relation to anything which is at present known. The per cent of total sulfate sulfur in the average control day urines is given as line A, the order of sequence being the same as that in the general table (I).

Arranged in the same way (line B) are the increments in per cent of total sulfur following the administration of cystine, that is the cystine sulfur eliminated. The two sets have about the same range, but are by no means parallel. The 81 per cent of the controls does not come opposite the 93 per cent of the eliminations nor does the 36 per cent from the line of eliminations come opposite the 30 per cent in control.