Immunoglobulin, protein adsorption

Lassen and Malmsten have performed ellipsometrically determined in situ protein adsorption measurements on the above plasma polymer surfaces with human serum albumin (HSA). human immunoglobulin (IgG), and human fib-... 

Lens hazing and protein deposition are common problems for wearers of soft contact lenses. Previous experiments with hydrophobic-hydrophilic copolymers exposed to plasma showed protein adsorption to be minimal at intermediate copolymer compositions. Adsorption of proteins from artificial tear solutions to a series of polymers and copolymers ranging in composition from 100% poly (methyl methacrylate) (PMMA) to 100% poly(2-hydroxyethyl methacrylate) (PH EM A) was measured. The total protein adsorption due to the three major proteins in tear fluid (lysozyme, albumin, and immunoglobulins) was at a minimum value at copolymer compositions containing 50% or less PH EM A. The elution of the adsorbed proteins from these polymers and copolymers with various solutions also was investigated to assess the binding mechanism. 

Recent experiments indicate that polymers that contain a balance of hydrophobic (nonpolar) and hydrophilic (polar) chemical groups show minimal protein adsorption and cell adhesion (6). With the intent of rationally designing a contact lens material that would minimize protein adsorption, the adsorption of lysozyme, albumin, and immunoglobulin G (IgG) to a series of hydrophobic and hydrophilic polymers and copolymers was measured. The polymers ranged from 100% poly(methyl methacrylate) (PMMA) to 100% poly(2-hydroxyethyl methacrylate) (PHEMA). Adsorption varied significantly for each protein, as did the elutability of the proteins from the surfaces. 

In-situ ATR FTIR spectroscopy was used to study the interaction between the differently charged model proteins human serum albumin, lysozyme, immunoglobulin G and multilayer assemblies, which were deposited by alternating adsorption of polyethyleneimine and polyacrylic acid onto silicon crystals. Low adsorbed protein amounts were observed if the top polyelectrolyte layer and the protein were equally charged, whereas enhanced protein adsorption occurred for electrostatic attraction between protein and top polyelectrolyte layer. 18 refs. 

Holmberg M, Hou XL (2010) Competitive protein adsorption of albumin and immunoglobulin G from human serum onto polymer surfaces. Langmuir 26 938-942... 

Another application shows the preparative purification and polishing of a therapeutic fusion protein with a humanized recombinant IgG protein. The fusion protein was expressed by the fermentation of baby hamster kidney cells. The filtered culture supernatant (155 liters) contained 2.2 g of IgG and 75.5 g of total protein. After the immunoglobulins were isolated by expanded bed adsorption and rebuffering, the IgG fraction was bound to Fractogel EMD SOj (M). This column achieved baseline separation of complete antibodies (fusion protein) from small amounts of antibodies lacking the fusion part. The resulting highly purified IgG fraction (110 ml) was diluted to 150 ml and... 

Two investigations have combined TIR with FCS thus far. The first(126) adapted TIR/FCS to measure the absolute concentration of virions in solution. The other(127) measured the adsorption/desorption kinetics of immunoglobulin on a protein-coated surface on the millisecond time scale. 

The adsorption of protein on colloidal gold occurs in a relative small pH range. Immunoglobulins are bound at pH 7.4, Protein A has an optimum at pH 6.5. For adjusting the pH, the gold colloid as well as the protein solution are dialyzed twice at RT against a 100-fold volume of Soln. A for 1 h each. 

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