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Letters to Nature

Nature 165, 927-928 (10 June 1950) | doi:10.1038/165927a0

Nature of Placental Cholinesterase

M. G. ORD & R. H. S. THOMPSON

  1. Department of Chemical Pathology, Guy's Hospital Medical School, London, S.E.1. Feb. 7.
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IN the course of a study of the types of cholinesterase occurring in different mammalian tissues, we have examined the ability of both fresh and perfused human placentas to hydrolyse acetyl choline, acetyl-beta-methyl choline and benzoyl choline. Torda1 had previously shown that perfused, blood-free placental tissue hydrolysed acetyl choline; but she did not report on the specificity of the enzyme in this tissue. Typical results which we have obtained using Mendel, Mundell and Rudney's "specific" substrates2 are given in the accompanying table. Enzymic activity has been measured by the Warburg technique using homogenized preparations of fresh and perfused placentas; in the latter case, the tissue was perfused with tap-water through the umbilical vein until the effluent fluid was no longer visibly blood-stained.