A sedimentation equilibrium study of the temperature-dependent association of bovine β-casein

Takase, Kazuma; Niki, Ryoya; Arima, Shunrokuro

doi:10.1016/0005-2795(80)90152-x

Cited by 34 publications

(17 citation statements)

References 20 publications

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“…12,22,53 CMC values determined for the no-sugar-PBS system at 25 1C and ionic strength of 0.1 M (0.72 AE 0.04 mg ml À1 ) were a bit smaller than the CMC value reported for b-Cas under identical conditions using ITC (B0.8 mg ml À1 ) 12 and slightly higher than the CMC value determined using the sedimentation equilibrium technique (B0.7 mg ml À1 ) at 20 1C in a 0.2 M sodium phosphate buffer of pH = 6.7. 54 Overall our results are thus in good agreement with the literature, and small differences may be due to different raw materials used, to differences in the methods for CMC determination and in the mathematical determination of CMC. 50 The effect of decreasing the CMC of b-Cas by the three aldohexoses, shown in Fig.…”

Section: Pyrene Fluorescencesupporting

confidence: 89%

The effect of sugar stereochemistry on protein self-assembly: the case of β-casein micellization in different aldohexose solutions

Setter

Livney

2015

Phys. Chem. Chem. Phys.

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Protein self-assembly applications, such as nanoencapsulation of drugs and nutraceuticals, require deep understanding of the parameters governing the micellization process, including the effects of ionic and non-ionic co-solutes, like salts and sugars respectively, which is often overlooked. Herein, with the aim of shedding light on the effect of nonionic cosolute stereochemistry on protein self-assembly, we studied the ternary system of water-protein-sugar by examining the concentration-dependent effects of three aldohexoses, d-glucose (Glu), d-galactose (Gal) and d-mannose (Man) and that of urea, on the micellization of beta casein (β-Cas), using pyrene as a fluorescent probe for the formation of hydrophobic domains. Pyrene's excitation spectra were recorded for several sets of samples with rising protein concentration (0-5 mg ml(-1)), each set with a different co-solute type and concentration. Critical micellization concentration (CMC) and cooperativity of micellization were evaluated according to changes in pyrene spectra as it partitioned from the aqueous environment to the hydrophobic cores of β-Cas micelles. All sugars examined lowered the CMC of β-Cas with increasing sugar concentration and with a diminishing degree of effectiveness (Glu > Gal > Man) which correlated well with the sugars' dynamic hydration number, defined by Uedaira, and correlated negatively with their hydrophobic to hydrophilic molecular surface ratio. These results support the hypothesis that sugars affect protein self-assembly through both changes in water structure and by hydrophobic interactions, both of which are evidenced to be highly sensitive to sugar stereochemistry.

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Section: Pyrene Fluorescencesupporting

confidence: 89%

The effect of sugar stereochemistry on protein self-assembly: the case of β-casein micellization in different aldohexose solutions

Setter

Livney

2015

Phys. Chem. Chem. Phys.

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“…l) As seen from Table 1, a rise in temperature from 25 "C to 38 "C contributes to decreasing the intrinsic viscosity and axial ratio from 23.1 cm3/g to 19.0 cm3/g, and from 16.8 to 14.3, respectively. With the data reported in [20] taken into account, such a decrease of the hydrodynamic parameters is indicative of the formation of associates more compact than separate polypeptide chains at 4 "C and the sphericity of which increases with temperature. This Hydrophobic interactions are very sensitive to ionic strenghts in solutions.…”

Section: Resultsmentioning

confidence: 91%

“…Therefore, under concrete conditions we may speak only of the most probable state of protein molecules. Using the equilibrium sedimentation results [20] we calculated the concentrational dependence of the monomer weight fraction vl) and associate weight fraction Vb) for /?-casein in a Na-phosphate buffer. In both cases inflection points are observed on the plots at a concentration of 0.3 g/100 ml when the associate fraction reaches about 80%.…”

Section: Resultsmentioning

confidence: 99%

Structure of protein solutions. Part 1. Investigation and interpretation of viscosity anomalies

Soloshenko

Сергеев

Безруков

1984

Nahrung

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The state of proteins in water-protein systems was investigated qualitatively using viscosimetric technique and preparative ultracentrifugation. In the case of cooperative processes, 4 concentration intervals bounded by three critical concentrations have been found for each protein.The first value of critical concentration is bound up with the initiation of supermolecular formations (herein also referred to as associates) due to self-association of polypeptide chains. The second critical concentration is observed when the weight fraction of associate becomes predominant (80-85 %) and when the change of secondary and tertiary structures is completed.The third critical concentration is connected with the change in the nature of supermolecular formations. The thermodynamic stability of the water-protein system varies when the critical concentrations are passed through. The system is stable and, apparently, close to the true solution over the first concentration interval. As soon as the first critical concentration is reached, colloid particles appear in the system and become predominant after the second critical concentration is passed, and the solution should be considered as a colloid one.According to the generally accepted definition the solution is a uniphase system consisting of at least two components [I]. As far as water-protein mixtures are concerned, the term "solutions" is applied to systems which entirely differ in phase state and structure. Such is the case with slurries and dilute enzyme solutions, the latter being close to the true solutions.The purpose of our experimentation is to particularize the physical sense of the term "solutions" in application to water-protein systems and generalize the structural features and characteristics of water-soluble proteins in a wide range of temperatures and concentrations. The present paper is the first report on a series of our experiments wherein the relation between the volumetric processes in the system and the observed viscosity anomalies is discussed in the light of data obtained by other methods. Materials and methods Materials

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“…Owing to the problems of temperature-dependent and ionic strength-dependent self-association, the molecular weights and degrees of polymerization calculated for bovine 0-casein, not surprisingly, have been found to depend greatly on experimental conditions (Payens etal., 1969;Andrews etal., 1979;Arima et al, 1979;Buchheim and Schmitt, 1979;Takase et al, 1980;Thum et al, 1987a;Morris, 2001). Such behaviour was reviewed by Rollema (1992): the degree of polymerization (DP) has been shown to vary from about 10 to up to 60, although at room temperature a DP between 40 to 50 has been found to be most prevalent (Swaisgood, 1992).…”

Section: Releelnvpg Eiveslssse Esitrinkki Ekfqseeqqq Tedelqdkih Pfaqtmentioning

confidence: 99%

The Self-Assembly and Structure of Caseins in Solution

Morris

2002

Biotechnology and Genetic Engineering Reviews

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A sedimentation equilibrium study of the temperature-dependent association of bovine β-casein

Cited by 34 publications

References 20 publications

The effect of sugar stereochemistry on protein self-assembly: the case of β-casein micellization in different aldohexose solutions

The effect of sugar stereochemistry on protein self-assembly: the case of β-casein micellization in different aldohexose solutions

Structure of protein solutions. Part 1. Investigation and interpretation of viscosity anomalies

The Self-Assembly and Structure of Caseins in Solution

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