Biochemical changes in mouse brain myelin during experimental primary amoebic meningo-encephalitis

Myelin membranes were purified from normal as well as experimental primary amoebic meningo-encephalitis-afflicted mouse brains. Infected myelin fractions were observed to form a floating fraction in 0.32 M sucrose. Total proteins, total lipids, phospholipids, cholesterol and galactolipids decreased markedly due to amoebic infection. Phosphatidyl choline, phosphatidyl ethanolamine plus phosphatidyl serine and sphingomyelin were decreased with a concomitant increase in lysophosphatidyl choline, lysophosphatidyl ethanolamine plus lysophosphatidyl serine and phosphatidic acid. SDS-polyacrylamide gel electrophoresis of myelin proteins exhibited six major protein fractions. Marked depletion in proteolipid protein was observed; 5'-nucleotidase activity increased while Na,K-ATPase and Mg-ATPase activities decreased. Infected myelin Na,K-ATPase had lower Vmax and higher Km values than normal. Arrhenius plots of normal myelin Na,K-ATPase exhibited transition temperature at 22 degrees C while no transition temperature could be observed in case of infected myelin Na,K-ATPase.