THE GLYCYLTRYPTOPHAN (PEPTID) SPLITTING AGENT IN HUMAN SALIVA

FRANK SMITHIES
1912 Archives of Internal Medicine  
Rather more than a year since, Warfield1 claimed the discovery of a new enzyme in human saliva,"a substance which has the power to split glycyltryptophan" (a dipeptid). This hydrolyzing property of saliva was stated as being lost when saliva is acid or when heated to 100 C. Warfield's report bases his conclusions on the action on glycyltryptophan of twenty-eight specimens of saliva. Of this number, saliva was alkaline (where stated) in all the positive reactions and acid in all negative
more » ... ll negative glycyltryptophan tests. The use of tobacco, observed in seven instances, did not materially alter the result so long as the salivas remained alkaline. About six months after Warfield's communication, Weinstein,2 in writing of the"t ryptophan" test for carcinoma ventriculi, confirmed Warfield's findings. Weinstein's observations are indefinitely stated. The few experiments actually quoted admit of dubious conclusions (vide 1 to 3, and A-B). In a footnote Weinstein states that his colleague, Professor Gies,"although suggesting the probability of ereptic and tryptic excretion Dy tne salivary glanas, tninks it possible also that the tryptophan pro¬ ducing enzyme in mixed saliva is derived in part from the bacteria in the mouth, especially from cavities in carious teeth." Previous to Warfield's report, ptyalin (diastase) had been considered the essential enzyme in human saliva. Maltase can hardly be regarded as distinctive. It would seem that if human saliva contain a proteolytic enzyme, new problems in the physiology of digestion would be presented. The observations included in this report were made in the endeavor to determine the existence of the peptid-splitting agent in saliva, the nature of this agent and the conditions under which it might be evidenced.
doi:10.1001/archinte.1912.00060240003001 fatcat:dkfmktdlo5batcv67rku7yaaeq