The fate of xylose in the animal body.

Abstract

The very similar chemical properties, correlated with closely corresponding structural configurations of the pentoses and hex-oses, make difficult the elaboration of chemical methods for the determination of one in the presence of the other. The resistance of pentoses to fermentation by ordinary baker's yeast has furnished a means that has been used at times to separate the two types of substances for analytical purposes. In the present study this procedure has been employed to determine the pentoses in the blood following their administration intravenously. The reducing power of normal blood can not be removed completely by fermentation with yeast, but since this residual reduction seems to remain small and fairly constant no real difficulty arises. It is scarcely unjustifiable to assume that in the presence of pentoses the difference from the usual unfermented reducing power of the blood furnishes a reliable index of the amount of pentoses present.

The details of this series of experiments may be summarized as follows: One gram of xylose in 15 cc. of solution was injected into the marginal ear vein of a 2 to 2.4 kg. fasting rabbit. The blood samples (2 to 3 cc.) were collected at the following intervals: one the preceding day, one just before and one just after the experiment, others after one, two, four and eight hours, respectively. These were analyzed for non-protein nitrogen, blood sugar and reducing power after fermentation. For this latter determination the whole blood was incubated one hour at 37 C. with a suspension of yeast. Then the proteins were precipitated according to the Folin-Wu procedure, and the reducing power of the filtrate determined by the Shaffer-Hartmann method, the results being expressed in terms of glucose.