The oxytocic hormone of the posterior lobe of the pituitary gland

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Abstract
II. HNO2 very rapidly converts the hormone into a derivative A which has an oxytocic strength equal to 35% of that of the original substance. HNO3 alone or in conjunction with HNO2 changes A into a substance B with an oxytocic strength of 20%. Prolonged action of HNO2 transforms B into a substance D with an oxytocic strength of about 0.1%. HNO3 converts the hormone into a substance C with strength of 90%. HNO2 converts C into a substance with an activity of 20% which is probably identical with B.[long dash]III. The hormone was inactivated by dipeptidase, aminopolypeptidase and proteinase which were prepared from yeast. Each of these preparations seems to have another enzyme present which is responsible for the inactivation. The optimum pH for this enzyme is 7.4. Papain preparations contained a similar enzyme. The enzyme reduces the activity to about 0.7% of the original value.