C-terminus engineering of soybean proglycinin: improvement of emulsifying properties

Abstract

Introduction of the extension region of beta-conglycinin alpha' subunit at the C-terminus of proglycinin A1aB1b results in the improvement of its emulsifying properties. To understand the basic for such improvement, we introduced the alpha' and alpha extension regions to the A2B1a C-terminus, and the alpha extension and A5A4B3 hypervariable regions, and an oligopeptide composed of 20 negatively or positively charged residues to the A1aB1b C-terminus, creating A2B1aalpha', A2B1aalpha, and A1aB1balpha, A1aB1bA4IV, A1aB1bNeg and A1aB1bPos, respectively. All the modified versions were produced in Escherichia coli. Their molecular size, thermal stability, surface hydrophobicity, solubility and emulsifying ability were studied. Analyses of molecular size and thermal stability suggested that all the modified versions formed the proper conformation similar to that of the wild type (WT). Solubility was intrinsic to each mutant. At ionic strength 0.5, the emulsifying abilities of all mutants were better than that of the WT except A1aB1bPos and A1aB1bNeg, and at ionic strength 0.08, all mutants especially A1aB1bPos exhibited better emulsifying ability than did the WT. The order of stability of the emulsion at both ionic strengths (0.08 and 0.5) was A1aB1balpha >or= A2B1aalpha > A1aB1balpha' >or= A2B1aalpha' >> A1aB1bPos > A1aB1bA4IV >or= A1aB1bNeg > A1aB1b, A2B1a. These results indicate that the emulsion stability of proglycinin mutants depends on length and hydropathy profile of the polypeptides added to the C-terminus of proglycinin.

Crystal structure of a major seed storage protein, 11S proglobulin, from Amaranthus hypochondriacus: Insight into its physico-chemical properties

“…Many studies have revealed that a protein's emulsifying ability is actually dependent on the balance between the surface hydrophobicity and hydrophilicity (solubility or surface charge) (Prak, Nakatani, Maruyama, & Utsumi, 2007;Tang & Sun, 2010;Voutsinas, Cheung, & Nakai, 1983). The 11S proglobulins used in this study generally have similar surface hydrophobicity, as shown in Fig.…”

Ultrasound-Assisted Mild Heating Treatment Improves the Emulsifying Properties of 11S Globulins

“…Proteins extracted from soybeans are essential ingredients for industrial food products such as beverages and nutraceuticals because they are affordable, with health benefits [1][2][3]. However, untreated soy proteins are not readily applicable because of limited surface-active properties (e.g., emulsifying property) and solubility.…”

Purification, crystallization and preliminary crystallographic analysis of soybean mature glycinin A1bB2

“…A large number of European and Japanese soybean-allergenic patients have IgE antibodies to glycinin and -conglycinin (Holzhauser et al, 2009;Ito et al, 2011). The structural analysis of these proteins is essential for the improvement of the nutritional qualities and functional properties of these proteins, as well as for elucidation of their allergenicity (Prak et al, 2006(Prak et al, , 2007Prak & Utsumi, 2009;Tandang et al, 2005). However, because of the heterogeneity of the molecular species, it is difficult to crystallize mature glycinin prepared from normal soybean cultivars (Utsumi, 1992).…”