The respiratory quotient, or the ratio of the volume of carbon dioxid expired to the volume of oxygen inspired, in the case of protein oxidation is stated by Loewy1 to be 0.801. This relation depends on the net result of the oxidation of the many amino-acids of which protein is composed. It is apparent that when some of these amino-acids are converted into glucose which is eliminated in the urine, the respiratory quotient for protein will not hold true. It has been shown2 that the carbon of glycocoll and alanin is completely converted into glucose in the diabetic organism, and that three of the carbon atoms which are contained in aspartic and glutamic acids are similarly convertible into glucose. Dakin3 states that prolin and arginin yield glucose comparable in quantity to that yielded by glutamic acid. According to this author cystin and serin also yield glucose.
The reactions involving
LUSK G. EIGHTH PAPER ON THE DIABETIC RESPIRATORY QUOTIENT. Arch Intern Med (Chic). 1915;XV(5_2):939-944. doi:10.1001/archinte.1915.00070240148008