title: Membrane lipids can modulate guanylate cyclase activity of rat intestinal microvillus membranes.
abstract: Studies of the temperature dependence (10-40 degrees C) of guanylate cyclase in rat intestinal microbillus membranes reveal a change in energy of activation (slope of the Arrhenius plot) at 30 +/- 1 degree C. The break point temperature corresponds to the lipid thermotropic transition in these membranes previously characterized by differential scanning calorimetry (range: 23-39 degrees C; peak temperature, 31 degrees C). The break point temperature for guanylate cyclase also corresponds to that of a number of other microbillus membrane enzymes and of D-glucose transport. These activities are defined as "intrinsic" membrane activities by this operational criterion. Treatment with the nonionic detergent Lubrol WX increased the guanylate cyclase activity 4- to 8-fold and removed the discontinuity in the Arrhenius plot.
mesh_terms: D000818:Animals; D004161:Diphenylhexatriene / Q000494:pharmacology; D004789:Enzyme Activation; D006162:Guanylate Cyclase / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000201:enzymology*; D007421:Intestine, Small / Q000201:enzymology; D008081:Liposomes / Q000494:pharmacology; D008297:Male; D008563:Membrane Lipids / Q000494:pharmacology*; D008871:Microvilli / Q000201:enzymology; D011092:Polyethylene Glycols / Q000494:pharmacology; D051381:Rats; D013696:Temperature
chemical_list: D008081:Liposomes; D008563:Membrane Lipids; C017474:Lubrol WX; D004161:Diphenylhexatriene; D011092:Polyethylene Glycols; D006162:Guanylate Cyclase