The effect of membrane phospholipid acyl-chain composition on the activity of brain-β-N-acetyl-d-glucosaminidase

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Abstract
The phospholipid acyl-chain dependence of the membrane-bound lysosomal .beta.-N-acetyl-D-glucosaminidase was examined on control membranes from rat brain primary cell cultures and on membranes modified by culturing the cells in media supplemented with polyunsaturated fatty acids. The relationship between .beta.-N-acetyl-D-glucosaminidase activity and the membrane phospholipid acyl-chain composition was evaluated. An increase in the unsaturation level of phosphatidylethanolamines and phosphatidylcholines, the most abundant phospholipids in this membrane fraction, is related to the rate of the enzymic reaction. The Arrhenius plot of the enzyme activity in modified membranes shows break-temperatures, starting from approximately 15.degree. C. The apparent activation energy below and above the break-temperature is not correlated with phospholipid acyl-chain unsaturation.