Abstract
The physiological activity of the pressor and oxytocic principles of the posterior pituitary gland is not appreciably altered when treated with cysteine, in slightly alkaline solution, in contrast to the behavior of insulin. Reoxidation likewise did not affect the activity.
Inactivation resulted with benzylation or methylation of the reduced pitocin and pitressin whereas no effect on the activity of the reduced material resulted by such treatment. This demonstrated, furthermore, that both pitressin and pitocin were actually reduced by the cysteine in the above experiments.
The results obtained offer almost conclusive proof that these active principles contain sulfur in the disulfide form.
In addition the evidence obtained indicates the necessity of the presence of a sulfhydryl or a potential sulfhydryl group to the activity of both pitressin and pitocin.
Footnotes
- Received May 28, 1935.
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