Effect of pH on Conformation and Surface Hydrophobicity of Soybean Protein Isolate

Abstract

Abstract: Lowry method, ANS fluorescence probe, circular dichroism and fluorescent spectroscopy were applied to explore the solubility, surface hydrophobicity, secondary structure and tertiary structure of soybean protein isolate at different pH conditions. The results showed that the transformation from β-sheet structure to α-helix structure, and the microenvironment polarity of Trp residues revealed an obvious increase with increasing pH. A negatively linear correlation between the surface hydrophobicity and solubility of soybean protein isolate was observed. Meanwhile, the surface hydrophobicity of soybean protein isolate was negatively correlated with the amount of α-helix structure.

Key words: soybean protein isolate, pH, hydrophobicity, structure

CLC Number:

TS201.2

References

[1]Sheard P R，Fellows A，Ledward D Aaa，et a1．Macromolecular charge associated with the heat treatment of soya isolate[J]．Food Technology。1988，21：55—60
[2]Weining Huang，Sun Xiuzhi．Adhesive properties of soy protein modified by sodium dodecyl sulfate and sodium dodecylbenzenz sulfonate[J]．JAOCS，2000，77(7)：705—708
[3]Fukushima D.Recent progress of soybean protein isolate foods:chemistry，technology and nutrition[J].Food Reviews International，1991，7(3):323一351.
[4]Lowry O H, Rosembroug H J, Lewis A, et a.l Protein measurementwith the folin phenol reagent[J]. Journal of BiologicalChemistry, 1951, 193(1): 265-275.
[5]Kato A，Nakai S．Hydrophobicity determined by a fluorescence probe method and its correlation with surface properties of proteins[J]．Biochem Biophy Acta，980.624(1)：13—20
[6]Huang，W N，X Sun．Adhensive properties of soy proteins modified by Urea and Guanidine hydrechloride[J]．JAOCS，2000，77(1)：101—104
[7] Shigeru Hayakaya, Shuryo Nakai. Relationships of Hydrophobicity and net Charge to the Solubility of Milk and Soy Proteins. J Fod Sci, 1985 ,50:486.
[8] Andrés Moure, J. Sineiro, Herminia Domínguez, Juan Carlos Parajó. Functionality of oilseed protein products: A review. Food Research International, 2006,39(9):945-963.
[9]Shuryo Nakai.Structure一Funetion Relationships of Food Proteins with an Emphasis on the lmportance of Protein HydroPhobicity.Agri Food Chem,1983,31:676一683
[10]Petruecelli S,AnonMC.Relationship Between the Method of Obtentionand the Structural and Functional Properties of Soy Protein Isolates.2.SurfaceProPerties.Agri Food Chem，1994，42:2170一2176
[11]John P,Cherry.Protein Funetionality in Foods.ACS Symposium,1980,147
[12]Sreerama N,Venyaminov S Y U,Woody R W.Estimation of the number of α-helical and β-strand segments in proteins using circular dichroism spectroscopy[J].Protein Science,1999,8(2):370-380.
[13]Sano T,Ohno T,Otsuka-Fuchino H,Matsumoto J J,Tsuchiya T.Carp natural actomyosin:Thermal denaturation mechanism.Journal of Food Science,1994,59(5):1002-1008.
[14]Damodaran S.Amino acids,peptides,and proteins//Food Chemistry (3rd ed.).New York:Marcel Dekker,1996:321-429.
[15]Liu R,Zhao S M,Xiong S B,Xie B J,Qin L H.Role of secondary structure in the gelation of porcine myosin at different pH values.Meat Science,2008,80:632-639.
[16] Kato, A.; Tsutsui, N.; Matsudomi, N.; Kobayashi, K.; Nakai, S. Effects of partial denaturation on surface properties of ovalbumin and lysozyme. Agric. Biol. Chem. 1981, 45, 2788-2760.
[17]KALAPATHY U,HETTIARACHCHY N S,RHEE K C.Effect of drying methods on molecular properties and functionalities of disulfide bond-cleaved soy proteins[J].Journal of the American Oil Chemists'Society,1997,74(3):195-199.
[18]Vivian J T,Callis P R.Mechanisms of tryptophan fluorescence shifts in proteins[J].Biophysical Journal,2001,80(5):2093-2109.
[19]刘清亮，吴双顶等.皖南尖吻蛇毒糖增水解酶的荧光光谱研究.无机化学学报，1998，14(1):53-57
[20] Anna, M., Zofia, D. Differential scanning microcalorimetry study of the thermal denaturation of haemoglobin[J]. Biophysical Chemistry, 2005, 118: 93-101