Wheat albumins/globulins

Weiss, W., Huber, G., Engel, K.H., Pethran, A., Dunn, M.J., Gooley, A.A. 1997. Identification and characterization of wheat grain albumin/globulin allergens. Electrophoresis 18 826-833. 

Wheat proteins contain albumins, globulins, gliadins, and glutenins, these four basic proteins depending on their varied solubility in different solvents (Figure 3.9). 

Some cereal proteins are quite soluble in aqueous solution (albumins, globulins) but the functional proteins—prolamins and glutelins—are difficult to solubilize. This is important because, for example, we do not want wheat gluten proteins to be soluble in a dough system. However, in order to characterize proteins, it is usually necessary to have them in solution. Because the property of solubility is such an important one with respect to cereal proteins, we will dedicate this chapter to the topic. In keeping with the objectives of the book, we will attempt to approach the subject from the most general and fundamental basis. 

Figure 10.1 SE-HPLC of wheat flour proteins. Peak 1 polymeric proteins peak 2 gliadins peak 3 albumins/globulins.

Substrate Peanut Arachin gg Albumin Bovine Serum Albumin Bovine Hemoglobin B-Lacto- globulin Wheat Gliadin Yam Protein... 

Wheat protein fractions Symmetrical Size distribution of wheat protein fractions (albumins and globulins, gliadins, glutenins) prepared by extraction influence of oxidation on size distribution of high-MW glutenin [S. G. Stevenson, T. Ueno, and K. R. Preston, Anal. Chem. 71 8-14 (1999)]... 

The cause, as already stated, is due to the constituents of the proteins of flour. The proteins of wheat are glutenin and gliadin, which constitute the ordinary insoluble protein gluten. The soluble proteins are vegetable albumin and globulin also the proteoses, and amino acids, and amides occur in the process of fermentation. 

Allergy to flour dust in bakers has been known since 1700 [44, 45]. Baker s asthma is a well-known occupational disease caused by IgE-mediated sensitization to cereal - mainly wheat, rye and barley - proteins. Hjorth [46] stated that most baker s dermatitis was associated with an immediate-type hypersensitivity. Herxheimer [47, 48] studied the development of skin sensitivity in baker s apprentices for 5 years and showed that the percentage of sensitive subjects increased gradually until a constant figure of 20% was reached. Many different proteins were identified as allergenic in wheat flour, especially in the water-soluble albumin and globulin fractions [49]. There is extensive cross-reactivity between these cereals, and -to a minor extent - between them and other cereals such as oat, corn and rice [50]. 

When we look at the amino acid compositions of the proteins from starchy endosperm and aleurone layers (Sect. 2.1.2) we can get some indication as to how the different kinds of protein are distributed within the kernel (Table 2.6). In wheat, the aleurone layer protein is clearly different from that in the remainder of the endosperm, being extremely rich in arginine this could reflect a high globulin level. Rice aleurone grains, however, are rich in albumins [69]. 

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