Glycogen metabolism in human hormone-producing trophoblastic cells in continuous culture—II. Characterization of BeWo glycogen phosphorylase

Abstract

1. 1. Conditions were established for assaying glycogen phosphorylase in crude sonicates from a human gestational choriocarcinoma cell line in continuous culture (BeWo). 2. 2. In sonicates from fresh cells, the specific activity of phosphorylase in the absence of AMP‡ was 21·07±1·32 units/mg protein. 3. 3. Addition of AMP increased this activity by about 50 per cent. 4. 4. The rate reaction increased with temperature up to 40°C and fell off sharply after 43°C. 5. 5. It was determined that optimal pH in the presence and absence of AMP was approximately 6·8. 6. 6. K m’ s were determined to be 25·38 and 9·97 mM glucose 1-phosphate for the activities in the absence and presence of AMP, respectively. 7. 7.|It was concluded that BeWo phosphorylase seemed to resemble muscle phosphorylase, rather than liver phosphorylase.