Influence on the Neutral Sialidase Activity Contained in Resealed Ghosts by (A) Proteins Released From White Ghosts During the Procedure Used to Prepare Resealed Ghosts, (B) Hypoosmotic Treatment of Resealed Ghosts, and (C) Isoosmotic Treatment of Hypoosmotically Treated Resealed Ghosts
| Enzyme Source and Treatment . | Sialidase Activity at pH 7.2 ( μU/mg protein) . |
|---|---|
| White ghosts | 1.2 ± 0.05 |
| RG | 56.9 ± 2.3 |
| (A)RG plus 0.5 μg supernatant proteins | 56.1 ± 2.5 |
| RG plus 1 μg supernatant proteins | 55.4 ± 1.9 |
| RG plus 2.5 μg concentrate supernatant proteins | 56.5 ± 2.1 |
| RG plus 8 μg concentrate supernatant proteins | 57.2 ± 1.8 |
| (B)RG after hypoosmotic treatment | 53.2 ± 1.3 |
| (C)Hypoosmotically treated RG after isoosmotic treatment | 54.8 ± 1.8 |
| Enzyme Source and Treatment . | Sialidase Activity at pH 7.2 ( μU/mg protein) . |
|---|---|
| White ghosts | 1.2 ± 0.05 |
| RG | 56.9 ± 2.3 |
| (A)RG plus 0.5 μg supernatant proteins | 56.1 ± 2.5 |
| RG plus 1 μg supernatant proteins | 55.4 ± 1.9 |
| RG plus 2.5 μg concentrate supernatant proteins | 56.5 ± 2.1 |
| RG plus 8 μg concentrate supernatant proteins | 57.2 ± 1.8 |
| (B)RG after hypoosmotic treatment | 53.2 ± 1.3 |
| (C)Hypoosmotically treated RG after isoosmotic treatment | 54.8 ± 1.8 |
All assays were performed with 30 μg, as protein, of resealed ghosts using the fluorimetric method (for details, see Materials and Methods). Proteins released from white ghosts were added using adequate aliquots of the supernatant obtained after treatment of white ghosts followed by centrifugation (for details, see Materials and Methods). Alternatively, and to concentrate released proteins, the supernatant was lyophilised, suspended with distilled water, and desalted. Hypoosmotic treatment of resealed ghosts was accomplished with 5 to 1.25 mmol/L PBS, pH 7.2, at 4°C according to Steck and Kant35; isoosmotic treatment of hypoosmotically treated resealed ghosts was accomplished with 5 mmol/L PBS-0.15 mol/L NaCl buffer, pH 8.0, at 37°C for 40 minutes according to Steck et al.36 The data are the mean values of four to five experiments ± SD values.
Abbreviation: RG, resealed ghosts.