The relation of various enzymes to cellular membranes

Summary The effect of pretreatment by M/1 NaCl or M/2 CaCl₂ on 11 enzymatic activities was studied in cryostat sections. The various enzymes were found to differ in their-reactions to these ions. In addition, different enzymes varied in their sensitivity to various noxious agents after these two pretreatments.The results are interpreted in terms of phase reversals of emulsions that can be expected to form as the result of an interaction of membrane anionic lipids and ions, with formation of oil in water (o/w) systems with monovalent cations and water in oil (w/o) systems with divalent cations. This assumption leads to the following interpretation of the data: in most instances the sensitivity of enzymes which are probably situated in the hydrophilic layer in a o/w system was greater to noxious agents presumed to act in the aqueous layer; the sensitivity of those enzymes which are probably situated in the hydrophobic layer was greater to noxious agents which are presumed to act in the less hydrophilic layer when in a w/o system. Some discrepancies were noted and suggestions for explaining them were proposed.This investigation was supported by Grant No. 4 × 5109 from the National Institutes of Health, U.S. Public Health Service.Preliminary reports on parts of this study were presented at the second congress of Histo- and Cytochemistry in Frankfurt on the Main in August 1964 and at the Sixteenth Annual Meeting of the Histochemical Society in Philadelphia, Penn., in April 1965.