SUGAR FORMATION FROM PROTEINS. 411 



teins do not raise the fat metabolism, but rather diminish it. The pro- 

 tein displaces a corresponding quantity of fat from the metabolism, 

 and if the fat were the only source of sugar then in this case we would 

 expect a diminished elimination of sugar instead of an increased one. 

 Nevertheless the above action of protein upon sugar elimination is much 

 more easily explained by the assumption of a sugar formation from pro- 

 tein than from fat. 



The action of monamino-acids upon the carbohydrate metabolism 

 has also given important ground for the assumption of a sugar forma- 

 tion from protein. That a deamidation occurs in the animal body was 

 shown by the earlier observations of BAUMANN and BLENDERMANN. 

 Further proofs of this were furnished by the investigations of NEUBERG 

 and LANGSTEIN, where in feeding experiments with alanine they found 

 abundance of lactic acid in the urine, and P. MAYER 1 observed glyceric 

 acid in the urine after the subcutaneous injection of diaminopropionic 

 acid. As from amino-acids by deamidation ketone acids or oxyacids 

 may be formed (see Chapter XIV) it would be of interest to test the action 

 of amino-acids upon the carbohydrate metabolism. Several investiga- 

 tions have been carried on with this in view, such as those of LANGSTEIN 

 and NEUBERG, R. COHN and F. KRAUS, which have shown a very prob- 

 able formation of carbohydrate under the influence of amino-acids; but 

 the investigations of EMBDEN and SALOMON, and of EMBDEN and ALMAGIA 

 have positively shown, in a dog without a pancreas, that the amino- 

 acids can bring about a re-formation of carbohydrate. LUSK alone 

 and with RINGER 2 have shown the same for several amino-acids by 

 experiments on dogs poisoned with phlorhizin. According to the exper- 

 iments and calculations of the two last mentioned investigators glycocoll 

 and alanine can be completely transformed into glucose. Of the four 

 carbon atoms of aspartic acid and of the five carbon atoms of glutamic 

 acid three appear as glucose. 



The investigations of WEINLAND S tend to prove a sugar formation 

 from protein. He studied the formation of sugar in the chrysalis pulp 

 of the Calliphora and showed that the sugar formed thereby did not orig- 

 inate from the fat, but that the protein was the only material from 



1 Baumann, Zeitschr. f. physiol. Chem., 4; Blendermann, ibid., 6; Neuberg and 

 Langstein, Arch. f. (Anat. u.) Physiol., 1903, Suppl.; Mayer, Zeitschr. f. physiol. Chem., 

 42. 



2 Langstein and Neuberg, 1. c.; Cohn, Zeitschr. f. physiol. Chem., 28; F. Kraus, 

 Berl. klin. Wochenschr., 1904; Embden and Salomon, Hofmeister's Beitrage, 5 and 

 6, and with Almagia, ibid., 7; Lusk, Amer. Journ. of Physiol., 22; Ringer and Lusk, 

 Zeitschr. f. physiol. Chem., 66. 



3 Zeitschr. f. Biol., 49 (N. F., 31); with Krummacher, ibid., 52. 



