Wheat puroindolin

The foam-negative effects of lipids can also be counteracted with the addition of a lipid-binding protein, wheat puroindoline (PIN), to beer. The PIN may bind the residual free lipids in such a way that they can no longer destabilize the foam. (Adapted from Cooper et ah, 2002)... 

Several other proteins that bind emulsifiers follow the general trends of this model. For example, the properties of the lipid binding protein from wheat called puroindoline has broadly similar properties [15]. 

The research efforts discussed in the previous sections of this chapter have steadily elucidated the genetic/molecular basis for variations in endosperm hardness. What is still not very well understood at this stage is the physical mechanism that causes soft wheat to become hard as a result of changes in the puroindoline proteins. In order to make progress in this challenging problem, the science of adhesion needs to be invoked. 

Morris, C. F. 2002. Puroindolines The molecular genetic basis of wheat grain hardness. Plant Molecular Biology 48 633-647. 

Rahman, S., G. J. Jolly, J. H. Skerritt, and A. Wallosheck. 1994. Gloning of a wheat 15 kDa grain softness protein (GSP). GSP is a mixture of puroindoline-like polypeptides. European Journal of Biochemistry 223 917-925. 

The wheat endosperm contains two basic, cysteine-rich proteins, puroindolin a and b (PIN-a and -b). The name is derived from the presence of tryprophan-rich segments in the amino aicd sequences Trp-Arg-Trp-Trp-Lys-Trp-Trp-Lys in PIN-a and Trp-Pro-Thr-Trp-Trp-Lys in PIN-b. PIN-a consists of a peptide chain with 115 residues (Mr 12,479) and five disulfide bridges. The peptide chains of PIN-a and PIN-b are homologous to an extent of 60%. It has been shown that the puroindolins are identical to the basic friabilins which have been discovered on... 

---