Bovine serum albumin surface charge

Fig. 6. Plateau-values, I"P1 /mg m 2, of adsorption isotherms of lysozyme (LSZ), ribonuclease (RNase), a -lactalbumin (aLA), calcium-depleted (X -lactalbumin (aLA(-Ca )) and bovine serum albumin (BSA) on hydrophobic polystyrene (PS) and hydrophilic hematite (a — Fe203) and silica (Si02) surfaces. An indication of the charge density of the surface is given by the zeta-potential, C, and of the proteins by + and signs. Ionic strength 0.05 M T = 25°C. (Derived from Currie et al. 2003).

Shablakh et al. (1984) investigated the dielectric properties of bovine serum albumin and lysozyme at different hydration levels, at low frequency. Besides a relaxation attributed to the electrode—sample interface, they detected a further bulk relaxation that can be confused with a d.c. conduction effect. The latter relaxation was explained by a model of nonconductive long-range charge displacement within a partially connected water structure adsorbed on the protein surface. This model has nonconventional features that differ from the assumptions of other more widely accepted models based on Debye relaxations. 

Figure 3. Phase boundaries (r = 100) of six proteins, plotted as net surface charge density (net charge/nm ) vs. 1 (ionic strength) (O) bovine serum albumin ( ) lysozyme (A) ribonuclease (A) chicken egg albumin ( ) -lactoglobulin and ( ) trypsin.

Rezwan, K., Meier, L.P.. and Gauckler, L.J., Lysozyme and bovine serum albumin adsorption on uncoated sihca and AIOOH-coated sihca particles The influence of positively and negatively charged oxide surface coatings. Biomaterials, 26, 4351,... 

Basic proteins protamine (pKj = 12.4) and histone (pKj = 10.8) did not inhibit attachment. The effect of proteins on attachment were independent of surface charge density on the substratum and thus the decreased attachment in the presence of proteins may be due to non-electrostatic interactions. The behaviour of bovine serum albumin, which has a large number of non-polar side chains, indicates that hydrophobic interactions may be important (Tanford, 84 Goldsack and Chalifux, 85). The effects of hydrophyllic colloids on bacterial floccuTation have been studied by Hodge and Metcalfe (86) and the subject has been reviewed by Harris and Mitchell (87). 

---