Regulation of trout gill AMP deaminase by lipid bilayers. Effects of phospholipid composition and temperature.
Trout gill AMP deaminase is inhibited by liposomes made of synthetic phosphatidylcholines containing higher saturated fatty acids. A preincubation of 1 hr, at 4 degrees C, was necessary to obtain the maximal effect. At 4 or 25 degrees C, these phospholipids modified essentially the substrate affinity of the enzyme by increasing the Michaelis constant proportionally to the length of the fatty acid chain. At 13 degrees C, the liposomes decreased the Hill coefficient also, thus inducing a negative cooperativity. Natural phosphatidylcholine and phosphatidylserine were without significant effect on gill AMP deaminase while natural sphingomyelin exhibited a similar effect to that shown in the presence of synthetic phosphatidylcholines. These results are discussed in relation to a possible effect of sphingomyelins in vivo.
D000659:AMP Deaminase / Q000378:metabolism*; D000818:Animals; D005880:Gills / Q000201:enzymology*; D007700:Kinetics; D008051:Lipid Bilayers; D009709:Nucleotide Deaminases / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013696:Temperature; D013816:Thermodynamics; D014337:Trout
D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D009709:Nucleotide Deaminases; D000659:AMP Deaminase