Studies on gastric proteolysis. 4. Proteinase activity of gastric juice and gastric-mucosal extracts at pH 6 to 8
- 1 April 1959
- journal article
- research article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 71 (4) , 626-632
- https://doi.org/10.1042/bj0710626
Abstract
Slight proteinase activity, with a pH maximum in the range pH 6.8-7.2, was found in the gastric juice of 9 out of 14 normal subjects. Similar activity occurred with extracts of normal human, swine and calf gastric mucosa and with swine pyloric juice. This activity was present when contamination with saliva or duodenal contents was excluded and was not concentrated in the desquamated cells and leucocytes of the centrifuged deposit. It did not result from a slight perpetuation at neutral pH of the action of pepsin. The responsible enzyme is precipitated from gastric juice at about pH 5.0 by 50-100% saturation with ammonium sulphate. Castle''s intrinsic factor may be concentrated similarly but the 2 substances are different. Saliva, from five normal subjects, possessed weak proteinase activity with a pH maximum near pH 7.5. This activity is concentrated in the centrifuged deposit which contains mainly buccal squamous cells.Keywords
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