Abstract
It is well known that one of the actions of ACTH is fat mobilization. We previously proposed “ Calcium theory” on the action of ACTH ; ACTH stimulates calcium uptake to adipose tissue, and incorporated calcium ions stimulates lipolysis in the tissue. It has been clarified in this report that the stimulation of lipolysis via calcium ions results from increase of formation of lipase-fat (enzyme-substrate) complex.
This communication also examins the characters of adipose tissue lipase such as hormone-sensitive lipase and lipoprotein lipase. It was found that liver esterase antibody effectively precipitated both hormone-sensitive lipase and the lipoprotein lipase. In the presence of serum, a hormone-sensitive lipase prepared by the method of Dr. Vaughan shows the optimum at pH 8.0. On the other hand, the optimum decrease at pH 6.8 in the presence of NaCl or in the absence of serum. The lipoprotein lipase activity was clearly inactivated by acetone treatment.
From these results, it is suggested that hormone-sensitive lipase and lipoprotein lipase are the same entities, and not different ones.
