Proteins, polymer modified

Athreya, S.A., and D.C. Martin. 1999. Impedance spectroscopy of protein polymer modified silicon micromachined probes. Sens Actuators A 72 203. 

Separate unreacted protein from modified liposomes by gel filtration using a column of Sephadex G-75 or by centrifugal floatation in a polymer gradient (Derksen and Scherphof, 1985). 

The ionization properties of side-chain substituents will usually carry through into the peptide or protein and influence the behaviour of the polymer. However, the actual pATa values of the amino acid side-chains in the protein are modified somewhat by the position of the amino acid in the chain, and the environment created by other substituents. Typical pATa values are shown in Table 13.2. 

Surface-bound, neutral, hydrophilic polymers such as polyethers and polysaccharides dramatically reduce protein adsorption [26-28], The passivity of these surfaces has been attributed to steric repulsion, bound water, high polymer mobility, and excluded volume effects, all of which render adsorption unfavorable. Consequently, these polymer modified surfaces have proven useful as biomaterials. Specific applications include artificial implants, intraocular and contact lenses, and catheters. Additionally, the inherent nondenaturing properties of these compounds has led to their use as effective tethers for affinity ligands, surface-bound biochemical assays, and biosensors. 

Kochendoerfer GG, Chen SY, Mao F, Cressman S, Traviglia S, Shao H, et al. Design and chemical synthesis of a homogeneous polymer-modified erythropoiesis protein. Science 2003 299(5608) 884-887. 

Fang, F., Szleifer, I. Controlled release of proteins from polymer-modified surfaces. Proc. Natl. Acad. Sci. 2006,103, 5769-74. 

The combination of sohd phase peptide synthesis with polymer chemistry has proven to be a versatile method for the preparation of polymer-peptide hybrids. Introduction of native ligation methods even allows the synthesis of polymer modified polypeptides and proteins via an entire organic chemistry approach. In the field of polymer chemistry—besides the advances in NCA polymerization, which will be discussed by others and is therefore not part of the scope of this review—controlled radical polymerization has been shown to be a robust technique, capable of creating well-defined biofunctional polymer architectures. Through protein engineering, methods have been estabhshed that enable the construction of tailor-made proteins, which can be functionalized with synthetic polymer chains in a highly defined manner. 

Elegant work in which the chemical ligation methodology was used for the preparation of a polymer-modified protein was reported by Kochendoerfer... 

FIG. 3 Variation of the intrinsic viscosity of long alkyl-modified polyacrylic acids as a function of the concentration of bovine serum albumin in the solvent. Solvent used for dilutions 30 mM borate buffer pH 9 and protein (top curves) or same buffer plus 0.3 M NaCl and protein (bottom curves). Black circles polymer modified with 4 mol% of C18 side groups squares polymer modified with 3 mol% of C12 groups cross-circles unmodified poly (sodium acrylate). (Reprinted with permission from Ref. 33. Copyright 1998 American Chemical Society.)... 

FIG. 13 Log-log plot of the binding isotherms of amphiphilic proteins to amphiphilic poly anions. ( , o) /3-lactoglobulin to copolymer of maleic acid and octyl- or dodecyl vinylether, respectively pH 8.7 and ionic strength 0.1 M (data from Ref. 50). (0, , A) bovine serum albumin to C18 modified poly(acrylic acid), pH 9.0 in 30 mM NaOH-boric acid buffer. Modification rate 10, 3, and 1 mol% respectively (data from Ref. 63). Free protein in /rniol/L protein/polymer ratio in number of protein globules per 1000 monomers. 

FIG. 20 Sketch of the gelation-fluidification process in protein/hydrophobically-modified polymer systems. 

Bian, K. S. Sun. Adhesive performance of modified soy proteins polymers. Polym. Prepr. 1998, 39, 72-73. 

Kanazawa H, Yamamoto K, Kashiwase Y, Matsushima Y, Takai N, Kikuchi A, Sakurai Y, Okano T. Analysis of peptides and proteins by temperature-responsive chromatographic system using AT-isopropylacrylamide polymer-modified columns. J Pharmaceu Biomed Anal 1997 15 1545—1550. 

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