Soluble and membrane-bound forms of lipoprotein lipase in mouse lung tissue.
Homogenates of mouse lungs were separated by differential centrifugation into two fractions containing lipoprotein lipase, namely, a soluble and a membrane-bound fraction. Lipoprotein lipase was specifically identified by its inhibition by both protamine sulfate (3 mg/ml) and sodium chloride (0.9 mol/l). The enzymatic activity of each fraction was enhanced when serum was preincubated with the enzyme. Both enzyme fractions showed optimum activity at alkaline pH, but the membrane-bound enzyme showed a higher pH optimum. In addition, the apparent Km of the soluble enzyme was lower than that of the membrane-bound enzyme. It is concluded that there are two different forms of lipoprotein lipase in mouse lung tissue that differ in a number of aspects.
D000818:Animals; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008071:Lipoprotein Lipase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008168:Lung / Q000201:enzymology*; D008297:Male; D008566:Membranes / Q000201:enzymology; D051379:Mice; D011479:Protamines / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D012995:Solubility
D011479:Protamines; D012965:Sodium Chloride; D008071:Lipoprotein Lipase