59D-26 |
Polymerization of food proteins by microbial Transglutaminase from Streptoverticillium mobaraense |
C. W. PARK, Food science and nutrition, Yong-in University, Samgari San 141 Korea, Yong-in Si Koungki Do, 449-714, South Korea, W. S. Shin, Food safty research team, Korea Food Research Institute, 46-1 Baekhyeon -Dong Bundang, Songnam Si Kyonggi Do, 463-420, South Korea, Y. S. Jeong, Food engineering, Chunbuk University, Chunju Si Dukjin Gu, South Korea, and G. J. Woo, EasyBio system, Yuksam Do 83/11, Kangnam Gu Seoul, 135-080, South Korea. Recently, the use of enzyme to manipulate the functional properties of proteins has been circumvently concerned because of safety and nutritional effects. Our objective was to investigate gelation of globular proteins by mTGase originated from Streptoberticillium mobaraense for soybean glycinin, maleylated glycinin, bovine serum albumin (BSA) and ovalbumin (OVA). MTGase (EC 2. 3. 2.13) was purified from one-step method using an ion-exchange chromatography. Soybean glycinin was modified by maleic anhydride to the degree of 50% and 100% range. Protein concentration of 10 mg/mL was incubated with mTGase at 50°C for 0 to 240 min. The reaction products polymerized by mTGase were characterized by SDS-PAGE. Oscillatory shear measurements were employed to determine rheological properties of mTGase-treated proteins at 50 mg/mL in 0.01M Tris-HCl buffer, pH 7.5. Storage and loss moduli (G` and G°±) were measured at a constant frequency of 1 Hz and 50°C. The glycinin of soybean, Hwangkumkong variety, was susceptible to the mTGase reaction, although the basic subunit did not participate in the polymerization. Treatment with 1mM DTT and heat (70°C/15min) improved the polymerization of BSA, OVA and maleylated glycinin, which had been known to be poor substrates of mTGase. In oscillatory shear measurements, the protein solution exhibited near-zero storage moduli (G`, indication of gel elasticity) during the onset of mTGase treatment but progressively increased with the incubation time and eventually leveled off at the maximal G` values. The globular proteins including BSA and OVA have been known to be poor substrate, however, following treatment with reducing agent and heat, polymerization of BSA and OVA was improved compared with those of native state. In the case of glycinin, the basic subunit of glycinin after maleylation participated in the polymerization mediated by mTGase. In conclusion, globular proteins became more susceptible to the enzymatic reaction with partial denaturation.
Session 59D, Food Chemistry: Proteins and Physicochemical Properties
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