COMPARISON OF THE THERMOSTABILITY OF GROWTH AND KETOGENIC ACTIVITIES OF ANTERIOR PITUITARY EXTRACT

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Abstract
Portions of an alkaline extract of beef ant. pituitary were heated on a boiling water bath at pH 10.0, 7.5, 4.5, 2.0, and 1.0, and after readjustment to neutrality each portion was assayed for its growth promoting and ketogenic potencies. Both activities showed maximum thermostability in the acid range and were practically completely destroyed at pH 10.0. Growth activity was most stable at pH 2.0 and ketogenic activity at pH 4.5. At pH 2.0, 50 %of growth potency was retained and only 6% of ketogenic potency. The substantial alteration in potency ratios after heating at pH 2.0 strongly suggests that growth and ketogenic activities are due to 2 separate principles.