Physical Properties of Mammalian Sialidases

Most of the studies on the properties of sialidase have been done with particulate cellular fractions which have sialidase activity. The enzyme environment is influenced by the membrane components and the results obtained for the particulate enzyme may be quite different from those obtained if the enzyme could be studied free from membrane components. 

Many workers have studied the pH optimum of mammalian sialidases located in different cell fractions and acting upon different substrates. Table III is a compilation of the data obtained. In all the results obtained, the pH optimum for sialidase appears to be acidic, usually between pH 4 and 5. There are a few soluble preparations which have reported pH optima greater than 5, which may possibly indicate contaminating microbial sialidase. At higher ionic strengths, the pH optimum for microbial sialidases can become more acidic (Barton et aL, 1975). This possibility should be carefully investigated for soluble preparations. 

Guinea pig, bovine and Whole brain homogenate Endogenous sialyl-containing 3.S. 0 Morgan and Laurell (1%3) 

Calf brain Gray matter acetone powder Di- and trisialo-gangliosides 4.4 Leibovitz and Gatt (1968) 

Pig brain Purified ( 600-fold) Gangliosides 4.9 Tettamanti and Zambotti 

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