Polymerization of protein

F. Oozawa, S. Asakura. Thermodynamics in the Polymerization of Proteins. New York Academic Press, 1975. 

The theory of reversible helical polymerization of proteins has been fully described by Oosawa and Asakura (1975). The following equation describes polymer growth ... 

Oosawa, F. Asakura, S. (1975). Thermodynamics of the polymerization of protein. Academic Press, London. 

Prion diseases resulting in encephalopathy can be transmitted between individuals within species (more rarely between species) [26-28], A conformational variant of the normal cellular protein PrPs (PrPc) (protease-sensitive or cellular) is believed to catalyze [29] or nucleate [30-33] conversion to the pathological form, PrPR (protease-resistant). This highly unusual nongenetic mode of transmission of an infectious agent has been strongly debated [29]. The observation of multiple examples of nucleated catalysis of aberrant polymerization of protein subunits has... 

Most references to the use of EDC describe the optimal reaction medium to be at a pH from 4.7 to 6.0. However, the carbodiimide reaction occurs effectively up to at least pH 7.5 without significant loss of yield. Conjugations done under mildly alkaline pH conditions (e.g., pH 8.5) also can be done to limit the polymerization of proteins, while still facilitating the coupling of a carboxylate-containing molecule at a low substitution level per protein. See Chapter 19,... 

Since activated molecules and crosslinks formed between two species are identical to those formed using SPDP, it is of little advantage to use PDTP. Furthermore, an EDC-mediated reaction of the carboxylate end of the crosslinker with amine groups on proteins can cause concomitant zero-length crosslinking and polymerization of protein molecules. For these reasons, SPDP is the better choice for preparing conjugates. 

Bz s-imidoesters like DMS may be used to couple proteins to PE-containing liposomes by crosslinking with the amines on both molecules (Figure 22.24). However, single-step crosslinking procedures using homobifunctional reagents are particularly subject to uncontrollable polymerization of protein in solution. Polymerization is possible because the procedure is done with the liposomes, protein, and crosslinker all in solution at the same time. 

The initial products of the reactions between sugars and proteins may enter a cascade of reactions yielding fluorescence, browning, and polymerization of proteins ("cross-linking"). The brown pigments, so-called melanoidins, are polymers whose composition has not yet been established completely. Melanoidins bind calcium and may thus interfere with de- and remineralization in caries. 

F. Oosawa S. Asakura (1975) Thermodynamics of the Polymerization of Protein, Academic Press, New York. 

Laki, K. (1951). The polymerization of proteins The action of thrombin on fibrinogen. Arch. Biochem. Biophys 32, 317-324. 

A promising method for reducing allergenicity relies on the polymerization of proteins with polyethylene glycol (PEG). Conjugation of whey proteins with nontoxic... 

Figure 3-4 Reactions Involved in Sulfhydryl Polymerization of Proteins. Source From O. Kirchmeier, The Physical-Chemical Causes of the Heat Stability of Milk Proteins, Milchwis-senschaft (German), Vol. 17, pp. 408-412,1962.

The processes of polymerization of protein monomers into filaments, such as actin and tubulin, can be investigated based on a simple kinetic model. To develop a model, we let Ai represent the monomer and At represent the filaments made up of l subunits. Our simple kinetic model has two distinct steps ... 

Fig. 6. Cyclization and polymerization of proteins. Two approaches that employ inteins for the generation of circular recombinant protein, split intein system (A), and TWIN system (B), are demonstrated. (A), The target protein is inserted between the C-terminal intein (C-intein) and the N-terminal intein (N-intein) segment. After spontaneous intein assembly, the standard splicing reaction results in excised intein and cyclized target protein. (B), The two intein systems sandwich the target protein between two intein-CBD tags. Controlled C- and N-terminal intein cleavages lead to target protein owning both N-terminal cysteine and C-terminal thioester. Whereas the intramolecular condensation forms cycUzed proteins, intermolecular reaction gives dimeric and polymeric proteins.

Hossain, M.I. et al., Contribution of the polymerization of protein by disulfide bonding to increased gel strength of walley pollack surimi gel with preheating time, Fisheries Sci., 67, 710, 2001. 

Kinetic analyses in the absence of denaturants provided evidence that the conversion process can be separated into two stages, first the binding of PrP-sen to PrP and then a slower conversion of the bound PrP-sen to PrP-res (Bessen et al, 1997 DebBurman et al, 1997 Horiuchi et al, 1999). These observations, and the formation of amyloid fibril polymers by PrP-res, are consistent with an autocatalytic or templated nucleated polymerization mechanism. However, the fact that PrP-res usually induces the conversion of only substoichiometric quantities of PrP-sen in current cell-free reactions makes the reaction less continuous than typical nucleated polymerizations of proteins or peptides. This may be a technical problem rather than a fundamental limitation of the reaction mechanism. On the other hand, since PrP-res forms continuously for long periods of time in vivo, there may be important elements of the mechanism, such as cofactors or microenvironments, that remain to be elucidated (DebBurman et al, 1997 Saborio etal, 1999). 

However, before reaching the consumer, food emulsions undergo a variety of processes including chemical reactions such as denaturation, polymerization of protein, interface aging and lipid oxidation[2,9]. The latter has an appreciable influence on the technological, sensory and nutritional qualities of the products[3, 9, 10]. 

Biomol. Chem. 2003. Copyright 2003 PCS.) (b) Features of helical supramolecular polymerization ordinate unimer + linear oligomer concentration helical polymer concentration C average degree of polymerization DPn. Abscissa total initial unit concentration. (From F. Oosawa and S. Asakura. Thermodynamics of the Polymerization of Protein. London Academic Press, p. 25, 1975. With permission.)... 

---