Calcium-Dependent Proteases in Neuroblastoma Cells

Abstract: Extracts of neuroblastoma cells contained calcium-dependent proteolytic activity. This activity was accounted for by two distinct proteases. These proteases were separated by ion-exchange chromatography. Although each was totally dependent on calcium, the calcium requirements of the enzymes were different; one enzyme required approximately 40 μM Ca²⁺ for half-maximal activity and the other enzyme required approximately 150 μM Ca²⁺ for half-maximal activity.     

Studies on the biosynthesis of dolichyl phosphate: Evidence for the in vitro formation of 2,3-dehydrodolichyl phosphate

A particulate enzyme preparation from hen oviduct is shown to carry out the biosynthesis of a long chain polyprenyl phosphate from isopentenyl pyrophosphate and farnesyl pyrophosphate. The compound has the physical and chemical properties of 2,3-dehydrodolichyl phosphate. The enzyme system is inhibited by EDTA and stimulated by Triton X-100 and dithiothreitol. If the product of the reaction is 2,3-dehydrodolichyl phosphate, it may be derived from 2,3-dehydrodolichyl pyrophosphate, a likely intermediate in the biosynthesis of dolichyl phosphate.     

Crucial demonstration of the proliferative growth regulating property of the naturally occurring chemical equilibrium composed of sulfhydryl and its partially oxidized derivatives

Summary and conclusion Four experimental criteria have been set up which are essential for the postulate that growth by increase in cell number is regulated by the naturally occurring chemical equilibrium composed of the sulfhydryl group and its partially oxidized derivatives.It has been shown that two of these have already been satisfied, and that a third can be considered as indirectly established. Report is made of an experiment which discharges the fourth.The cumulative data thus lead to the conclusion that the postulate is a true expression of a basic biological principle.Grateful acknowledgement should be given to the International Cancer Foundation established by Mr. Wm. H.Donner of Philadelphia for support in this work.These experiments were done at The Marine Experiment Station of The Research Institute of The Lankenau Hospital, North Truro, Massachusetts, under grants from Mr.August Bein of Philadelphia, and the Capt. L. D.Baker Estate of Boston and Wellfleet.