Action of Acidic and Neutral Sialidases on Endogenous Substrates (Glycolipids and Glycoproteins)
| . | Before Incubation . | After Incubation . | |
|---|---|---|---|
| . | . | pH 4.7 . | pH 7.2 . |
| Ganglioside-bound sialic acid | 9.7 ± 0.5 | 2.9 ± 0.2 | 3.2 ± 0.1 |
| Released sialic acid (%) | 0 | 70.1 | 67 |
| Protein-bound sialic acid | 134.6 ± 7.5 | 134.8 ± 5.4 | 115.7 ± 4.2 |
| Released sialic acid (%) | 0 | 0 | 14 |
| Total sialic acid | 147.8 ± 8.2 | 141.6 ± 8.2 | 122.4 ± 6.1 |
| Released sialic acid (%) | 0 | 4.2 | 17 |
| . | Before Incubation . | After Incubation . | |
|---|---|---|---|
| . | . | pH 4.7 . | pH 7.2 . |
| Ganglioside-bound sialic acid | 9.7 ± 0.5 | 2.9 ± 0.2 | 3.2 ± 0.1 |
| Released sialic acid (%) | 0 | 70.1 | 67 |
| Protein-bound sialic acid | 134.6 ± 7.5 | 134.8 ± 5.4 | 115.7 ± 4.2 |
| Released sialic acid (%) | 0 | 0 | 14 |
| Total sialic acid | 147.8 ± 8.2 | 141.6 ± 8.2 | 122.4 ± 6.1 |
| Released sialic acid (%) | 0 | 4.2 | 17 |
Enzyme preparation was resealed vesicles from human erythrocyte membranes. Incubation conditions was 50 mmol/L citric acid-sodium phosphate-0.15 mol/L NaCl, pH 4.7 and 7.2 (for the acidic and neutral sialidase, respectively), for 18 hours at 37°C. Data are expressed as nanomoles of total-bound, ganglioside-bound, and glycoprotein-bound sialic acid per milligram protein. The data are the mean values of five experiments ± SD values.