Müller's work1 suggested that malignant tumors contain one or more proteolytic enzymes. Emerson,2 Fischer3 and many others have shown that such is the case. Recently Neubauer and Fischer4 and Abderhalden and his associates5 have found that malignant growths contain an enzyme capable of splitting certain polypeptids into amino-acids. Neubauer and Fischer4 have introduced, on this basis, the so-called "glycyltryptophan test" for carcinoma of the stomach.
Lyle and Kober6 regarded the glycyltryptophan test as a very good one, especially if more than two tests on every case are carried out. Weinstein7 has shown that the use of glycyltryptophan is unnecessary for the detection of a tryptophan-producing enzyme in gastric contents, since gastric contents always contain proteoses and peptones that are easily convertible by cancer enzyme into their hydrolytic products, among which tryptophan would be included. Therefore it is unnecessary to add a
SANFORD CH, ROSENBLOOM J. THE GLYCYLTRYPTOPHAN AND TRYPTOPHAN TESTS FOR CANCER OF THE STOMACH. Arch Intern Med (Chic). 1912;IX(4):445-451. doi:10.1001/archinte.1912.00060160048005