• 한국수산과학회지
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• 제54권4호
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• pp.543-551
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• 2021

Changes in gluten surface hydrophobicity, which play an important role in the functional characteristics of protein, were measured according to various protein concentrations, pH levels, electrolytes concentrations, and alginate molecular weights using 8-anilino-1-naphthalene sulfonic acid (ANS) as a fluorescent probe. Gluten surface hydrophobicity decreased as gluten concentration increased, reaching a maximum pH of 7.0. The effects of alginate molecular weights and alginate concentration on the surface hydrophobicity, emulsifying activity index (EAI), and emulsion stability index (ESI) of gluten-sodium alginate dispersion (GAD) were measured. Gluten surface hydrophobicity rapidly increased the asl NaCl concentration of gluten solution up to 300 mM and showed no significant increase above 300 mM. However, gluten surface hydrophobicity notably decreased until the concentration of CaCl₂ and MgCl₂ reached 30 mM, indicating no significant variations above 30 mM. GAD surface hydrophobicity increased as the concentration and molecular weight of sodium alginate increased, however, gluten concentration increased as the GAD surface hydrophobicity decreased. The EAI and ESI of GAD increased as both molecular weight and concentration of sodium alginate increased.

• 한국식품영양과학회지
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• 제45권9호
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• pp.1285-1292
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• 2016

분리콩단백질(SPI, soy protein isolate) 농도, pH, 전해질의 종류와 농도, alginates의 농도와 분자량이 SPI의 표면소수성에 미치는 영향을 조사한 결과는 다음과 같다. SPI 농도가 증가할수록 표면소수성은 감소하였다. SPI의 표면소수성이 pH 7.0에서 최대값을 나타내었다가 pH가 7.0을 기준으로 증가 혹은 감소함에 따라 표면소수성이 감소하는 경향을 나타내었다. SPI의 표면소수성은 NaCl의 농도가 100 mM까지 증가함에 따라 급격히 증가하지만 더 이상의 농도에서는 변화가 없었다. $CaCl_2$와 $MgCl_2$의 농도가 각각 50 mM과 30 mM까지 증가할수록 SPI의 표면소수성이 급격히 감소하였지만, 그 이상의 농도에서는 큰 변화가 없었다. Na-alginate의 농도와 분자량의 증가함에 따라 SPI의 표면소수성이 감소한 것으로 나타났다. Na-alginate의 분자량이 증가함에 따라 표면소수성의 증가속도가 감소하였다.

• Archives of Pharmacal Research
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• 제26권8호
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• pp.653-658
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• 2003

It has been reported that at low temperature region, poloxamers existed as a monomer. Upon warming, an equilibrium between unimers and micelles was established, and finally micelle aggregates were formed at higher temperature. In this study, the fluorescence spectroscopy was used to study the micelle formation of the poloxamer 407 in aqueous solution. The excitation and emission spectra of pyrene, a fluorescence probe, were measured as a function of the concentration of poloxamer 407 and temperature. A blue shift in the emission spectrum and a red shift in the excitation spectrum were observed as pyrene transferred from an aqueous to a hydrophobic micellar environment. From the $I_1/I_3 and I_{339}/I_{333}$ results, critical micelle concentration (cmc) and critical micelle temperature (cmt) were determined. Also, from the fluorescence spectra of the probe molecules such as 8-anilino-1-naphthalene sulfonic acid and 1-pyrenecarboxaldehyde, the blue shift of the $\lambda_{max}$ was observed. These results suggest a decrease in the polarity of the microenvironment around probe because of micelle formation. The poloxamer 407 above cmc strongly complexed with hydrophobic fluorescent probes and the binding constant of complex increased with increasing the hydrophobicity of the probe.

• BMB Reports
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• 제38권4호
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• pp.407-413
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• 2005

Calcium and zinc binding protein, calprotectin is a multifunctional protein with broad spectrum antimicrobial and antitumoural activity. It was purified from human neutrophil, using a two-step ion exchange chromatography. Since surface hydrophobicity of calprotectin may be important in membrane anchoring, membrane penetration, subunits oligomerization and some biological roles of protein, in this study attempted to explore the effect of calcium in physiological range on the calprotectin lipophilicity. Incubation of human calprotectin ($50\;{\mu}g/ml$) with different calcium concentrations showed that 1-anilino-8-naphthalene sulfonic acid (ANS) fluorescence intensity of the protein significantly elevates with calcium in a dose dependent manner, suggesting an increase in calprotectin surface hydrophobicity upon calcium binding. Our study also indicates that calcium at higher concentrations (6, 8 and 10 mM) induces aggregation of human calprotectin. Our finding demonstrates that the starting time and the rate constant of calprotectin aggregation depend on the calcium concentration.

• 대한화학회지
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• 제55권5호
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• pp.746-750
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• 2011

Fluorescence correlation spectroscopy (FCS) is an emerging fluorescence technique used to study the dynamics of proteins on a millisecond to microsecond time scale at the single-molecule level. Solution pH-modulated protein conformational changes can be manifested by binding rate, fluorescence lifetime, and binding specificity of a probe molecule. The fluorescence lifetime of Nile red (NR) bound to apomyoglobin (apoMb) was measured to be $6{\pm}0.3$ ns, much longer than that in water solution ($2.9{\pm}0.2$ ns). As the unfolding population of apoMb increased by lowering pH of solution, the fraction for the longer lifetime of NR decreased with an increasing fraction for the shorter lifetime of NR in water. Unlike 1-anilino-8-naphthalene sulfonic acid, which has many lifetimes due to nonspecific binding to the unfolded apoMb, NR bound to apoMb possesses only a single lifetime. These results suggest that NR binds specifically to native apoMb and thus can be utilized to probe the folding/unfolding dynamics of apoMb using FCS.