Self-assembly due to specific kinds of biopolymer interactions

Self-Assembly due to Specific Kinds of Biopolymer Interactions 

Caseins are highly disordered proteins having rather limited secondary structure. This is mainly due to the unusually high proline content, which is fairly uniformly distributed along the polypeptide chain. This feature leads to an open extended structure of the casein molecules which differentiates them from the globular whey proteins like a-lactalbumin and (3-lactoglobulin. The caseins have been described as rheomorphic  

In contrast, the whey proteins are relatively small globular proteins. a-Lactalbumin represents about 20 % of the protein content of bovine whey (3.5 % of total bovine milk protein), and it is the principal protein in human milk (Brew and Grobler, 1992). Nanotube assembly has been discovered in some solutions containing a hydrolysed derivative of this protein. And it appears that the a-lactalbumin nanotube is unique in the sense that it is the only artificial nanotube that has so far been made from a food protein (Graveland-Bikker et al., 2004 Graveland-Bikker and de Kruif, 2006). As for p-lactoglobulin, it has the capacity under certain specific conditions to form nano-fibres in aqueous media (as can various other globular food proteins, such as ovalbumin, soy proteins, and bovine serum albumin) (van der Linden, 2006 Nicolai, 2007). 

The most commonly investigated casein in model colloidal systems is bovine p-casein. It consists of a polypeptide chain of 203-209 amino 

The casein responsible for colloidal stabilization of the casein micelle is K-casein. This glycoprotein has a molecular weight of 19 kDa and is composed of 169 amino acids (Swaisgood, 2003). K-Casein is special in being the only casein component that is insensitive to calcium ions (up to concentrations of 400 mM). 

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