• 한국식품조리과학회지
• /
• 제6권3호통권12호
• /
• pp.9-15
• /
• 1990

Peanut prptein isolate was tested for the purpose of finding out the effect of pH, Sodium Chloride concentration and heat treatment on the solubility, surface hydrophobicity, foam expansion and foam stability. The solubility of peanut protein isolate was affected by pH and showed the lowest value at pH 4.5. When the peanut protein isolate was heated, the solubility decreased at pH 3 and pH 7 but at pH 9 solubility increased. At all pH range, solubility decreased as NaCl was added. The surface hydrophobicity of peanut protein isolate showed the highest value at pH 1.5. Generally, at acidic pH range the surface hydrophobicity was high, but at alkaline region, the surface hydrophobicity increased as the temperature increased. And when NaCl was added, the surface hydrophobicity was also increased. Foam expansion of peanut protein isolate was no significant difference among the values about pH. When the peanut protein was heated and NaCl was added, foam expansion was increased at pH 7. Foam stability was significantly low at pH 4.5 and foam stability was increased at acidic pH region below pH 4.5. At pH 7 and pH 9, heat treatment above $60^{\circ}C$ increased foam stability. When NaCl was added, foam stability was significantly increased at pH 3 and pH 7.

• 한국작물학회지
• /
• 제51권2호
• /
• pp.148-153
• /
• 2006

Effects of ${\alpha}$-chymotrypsin modification on degree of hydrolysis (DH), solubility, emulsifying capacity and thermal aggregation of laboratory-purified soy protein isolate (SPI) using a lipoxygenase-defected soybean (Jinpum-kong) and commercial soy protein isolate (Supro 500E) were compared. SPIs were hydrolyzed by ${\alpha}$-chymotrypsin at pH 7.8 and $37^{\circ}C$ for 30 min. DHs of Supro 500E and Jinpum-kong SPI were increased by ${\alpha}$-chymotrypsin modification, and DH of Supro 500E was higher than that of Jinpum-kong SPI. DH of ${\alpha}$-chymotrypsin treated Jinpum-kong SPI was similar with untreated Supro 500E and DH of treated Supro 500E was the highest. Solubility, emulsifying capacity and thermal aggregation of SPIs were increased by ${\alpha}$-chymotrypsin modification, and these changes were highly related to changes in DH. Functional properties of Supro 500E were higher than Jinpum-kong SPI in both of untreated and ${\alpha}$-chymotrypsin treated SPIs.

• 한국축산식품학회지
• /
• 제40권3호
• /
• pp.377-387
• /
• 2020

The aim of this study was to compare the effect of seawater to that of conventional salt (NaCl) on the technological properties of chicken emulsion sausages in a model system. Chicken sausages were prepared with seawater at three levels (10%, 15%, and 20%) in iced water (10%, 5%, and 0%, respectively) or with iced water (20%) and salt (1.2%). There was no difference in pH values and fat loss from emulsion stability between the two treatments. In general, with an increase in the amount of seawater, the water holding capacity (cooking yield and water loss), protein solubility (total and myofibrillar protein), and viscosity were increased. The addition of 20% seawater induced greater (p<0.05) water holding capacity, protein solubility, and viscosity compared to the control sample treated with salt, which was accompanied by an increase in the level of myosin heavy chain protein of samples with 10% and 20% seawater. Furthermore, addition of at least 15% seawater increased all of the main textural properties except for cohesiveness along with the moisture of sausage, whereas the fat and protein contents were decreased. Based on these results, the addition of ≥15% seawater to chicken breast sausage can induce equivalent or enhanced technological properties to those induced with salt, including water holding capacity, protein solubility, viscosity, and textural properties.

• 한국식품영양학회지
• /
• 제9권3호
• /
• pp.319-324
• /
• 1996

The functional properties of protein recovered from red crab (Chitinonecetes opiiie) processing in water (RCP) were examined and compared with those of soybean protein isolate at pH 2~10 in water and NaCl solu5ion. The solubilities of RCP and SPI were miniumu at pH 4, the isoelectric point and increased significantly at lower or higher than pH 4. Solubilities in NaCl solution for both proteins decreased with incr NaCl concentration increase at all pH ranges. Emulsion capacity for both proteins was also minimum at pH 4 and increased as protein concentration increased from 2 to 6%. Emulsion capacity of RCP was higher than these of SPI at pH 6∼10 and all protein concentrations. Emulsion stability showed a similar trend to that of emulsion capacity. RCP had higher oft absorption capacity and lower water absorption capacity than SPI.

• Journal of Applied Biological Chemistry
• /
• 제42권4호
• /
• pp.180-185
• /
• 1999

Protein concentrate was produced and succinylated from rice bran to assess and improve its functional properties for the purpose of expanding the uses of rice bran proteins. The most effective solvent for the extraction of rice bran proteins was 20% aqueous ethanol at pH 9. The protein content of rice bran protein concentrate produced was 70.0% and the total protein yield was 64.3%. The extent of succinylation of free amino groups in the modified products was 72.8%. Though the modified protein products showed good functional properties including solubility, emulsion properties, and oil absorption capacity, it did not form gel. Succinylation improved solubility and emulsion and gelling properties. These improvements in functionality will enhance the value of rice bran proteins, thus enabling them to be more competitive with other food proteins.

• Bulletin of the Korean Chemical Society
• /
• 제32권5호
• /
• pp.1640-1644
• /
• 2011

Water-soluble mutant of intrinsically insoluble protein, crambin, was produced by mutagenesis based on the sequence analysis with homologous proteins. Thr1, Phe13, and Lys33 of crambin were substituted for Lys, Tyr, and Lys, respectively. The resultant mutant was soluble in aqueous buffer as well as in dodecylphosphocholine (DPC) micelle solution. The $^1H-^{15}N$ spectrum of the mutant crambin showed spectral similarity to that of the wild-type protein except for local regions proximal to the sites of mutation. Solution structure of water-soluble mutant crambin was determined in aqueous buffer by NMR spectroscopy. The structure was almost identical to the wild-type structure determined in non-aqueous solvent. Subtle difference in structure was very local and related to the change of the intra- and inter-protein hydrophobic interaction of crambin. The structural details for the enhanced solubility of crambin in aqueous solvent by the mutation were provided and discussed.

• Journal of Microbiology and Biotechnology
• /
• 제32권11호
• /
• pp.1471-1478
• /
• 2022

2'-Fucosyllactose (2'-FL), the most abundant fucosylated oligosaccharide in human milk, has multiple beneficial effects on human health. However, its biosynthesis by metabolically engineered Escherichia coli is often hampered owing to the insolubility and instability of α-1,2-fucosyltransferase (the rate-limiting enzyme). In this study, we aimed to enhance 2'-FL production by increasing the expression of soluble α-1,2-fucosyltransferase from Helicobacter pylori (FucT2). Because structural information regarding FucT2 has not been unveiled, we decided to improve the expression of soluble FucT2 in E. coli via directed evolution using a protein solubility biosensor that links protein solubility to antimicrobial resistance. For such a system to be viable, the activity of kanamycin resistance protein (Kan^R) should be dependent on FucT2 solubility. Kan^R was fused to the C-terminus of mutant libraries of FucT2, which were generated using a combination of error-prone PCR and DNA shuffling. Notably, one round of the directed evolution process, which consisted of mutant library generation and selection based on kanamycin resistance, resulted in a significant increase in the expression level of soluble FucT2. As a result, a batch fermentation with the ΔL M15 pBCGW strain, expressing the FucT2 mutant (F#1-5) isolated from the first round of the directed evolution process, resulted in the production of 0.31 g/l 2'-FL with a yield of 0.22 g 2'-FL/g lactose, showing 1.72- and 1.51-fold increase in the titer and yield, respectively, compared to those of the control strain. The simple and powerful method developed in this study could be applied to enhance the solubility of other unstable enzymes.

• Journal of Microbiology and Biotechnology
• /
• 제16권2호
• /
• pp.299-302
• /
• 2006

A combinatorial library of artificial transcription factors (ATFs) was introduced into the bacterial cells that expressed the Akt1-GFP fusion protein. By measuring the level of fluorescence generated by the transformed E. coli cells, we were able to obtain clones in which ATFs increased the solubility of the Akt1. Our results show that ATF library is a useful tool for increasing the solubility of selected recombinant proteins in E. coli.

• 한국식품영양과학회지
• /
• 제18권4호
• /
• pp.410-422
• /
• 1989

숙시닐화 또는 트립신처리에 의한 대두단백질분리물의 화학적 변형은 단백질의 함량을 감소시키는 것으로 나타났고, 아미노산 조성에서 tyrosine의 증가가 현저하였으나 lysine은 트립신처리시에만 크게 증가하였다. 화학적 변형은 단백질의 용해성을 증가시키고 pH의존성이 뚜렷하여 등전점 변이시키는 효과를 나타내었다. 단백질의 용해성은 염류의 농도증가에 의해 감소하는 경향을 나타내었으며, 화학적 변형은 유흡수성과 수분흡수성, 유화특성 및 기포성 등을 증가시키는 반면에 기포안정성을 다소 저하시키고 자외선흡광도와 용적밀도를 감소시켰다. 한편 대두단백질 분리물과 우육단백질의 혼합에 따른 상호작용에 의해서는 유화활성, 유화활성지수 및 기포성의 증가를 가져봤으나 유화안정성에 대해서는 현저한 효과가 나타나지 않았다.