Dataset Information

Investigations on the Effect of Fatty Acid Additives on Casein Micelles: Role of Ethylenic Unsaturation on the Interaction and Structural Diversity.

ABSTRACT: Casein, one of the major constituent of milk protein, is considered to be a good candidate for oral drug delivery system. Also, milk transports various essential fatty acid to blood through dietary supplements. In this study, we have explored the alteration in the structural characteristic in terms of the modulations in the microenvironment of the protein in the presence of different types of fatty acids. Herein, we have observed that the unsaturation of fatty acids mostly affects the structure of casein micelles (CMs) by impinging upon the hydrophobic force of interaction following a decrease in the electrostatic interaction of various amino acid unit. Alteration of such forces is responsible for the increase in the aggregate size, modification in the protein secondary structure, and different morphology of CMs. Fluorescence behavior of 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran indicates that the rigidity of the microenvironment is the main characteristic of the fatty acid binding, and the binding constant increases with the fatty acid chain length for saturated fatty acid or with the introduction of unsaturation onto it. Fluorescence lifetime imaging microscopy study indicates that the microstructure of CMs becomes more compact in the presence of unsaturated fatty acids, and this is also responsible for the increase in the diffusion time of the probe. Moreover, decrease in the fluorescence of extrinsic probe 8-anilinonaphthalene-1-sulfonate with the addition of unsaturated fatty acid reveals that these fatty acids alter the electrostatic interaction between casein units, more specifically in case of the surface-bound ?-casein. Therefore, this study provides a very useful information on the binding of fatty acids and helps to evaluate other fatty acid, as well as different small molecules binding in the applicative medicinal purpose.

SUBMITTER: Panja S

PROVIDER: S-EPMC6641531 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Investigations on the Effect of Fatty Acid Additives on Casein Micelles: Role of Ethylenic Unsaturation on the Interaction and Structural Diversity.

Panja Sudipta S Khatua Deb Kumar DK Halder Mintu M

ACS omega 20180123 1

Casein, one of the major constituent of milk protein, is considered to be a good candidate for oral drug delivery system. Also, milk transports various essential fatty acid to blood through dietary supplements. In this study, we have explored the alteration in the structural characteristic in terms of the modulations in the microenvironment of the protein in the presence of different types of fatty acids. Herein, we have observed that the unsaturation of fatty acids mostly affects the structure ...[more]

PMID: 31457932

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Project description:Milk alpha-, beta- and kappa-casein proteins assemble into casein micelles in breast epithelial cells. The glycomacropeptide (GMP) tails of kappa-casein that extend from the surface of the micelle are key to assembly and aggregation. Aggregation is triggered by stomach pepsin cleavage of GMP from para-kappa-casein (PKC). While one casein micelle model emphasizes the importance of hydrophobic interactions, another focuses on polar residues. We performed an evolutionary analysis of kappa-casein primary sequence and predicted features that potentially impact on protein interactions. We noted more rapid change in the earlier period (166 to 60 Ma). Pepsin and plasmin cleavage sites were avoided in the GMP, which may partly explain its amino acid composition. Short tandem repeats have led to modest expansions of PKC, and to large GMP expansions, suggesting the GMP is less length constrained. Amino acid compositional constraints were assessed across species. Polarity and hydrophobicity properties were insufficient to explain differences between PKC and GMP. Among polar residues, threonine dominates the GMP, compared to serine, probably reflecting its preference for O-glycosylation over phosphorylation. Glutamine, enriched in the bovine PQ-rich region, is not positionally conserved in other species. Among hydrophobic residues, isoleucine is clearly preferred over leucine in the GMP, and patches of hydrophobicity are not markedly positionally conserved. PKC tyrosine and charged residues showed stronger conservation of position, suggesting a role for pi-interactions, seen in other structurally dynamic protein membraneless assemblies. Independent acquisitions of cysteines are consistent with a trend of increasing stabilization of multimers by covalent disulphide bonds, over evolutionary time. In conclusion, kappa-casein compositional and positional constraints appear to be influenced by modification preferences, protease evasion and protein-protein interactions.

Project description:OBJECTIVE:Caseins and fatty acids of milk are synthesized and secreted by the epithelial cells of the mammary gland. All-trans retinoic acid (ATRA), an active metabolite of vitamin A, has been shown to promote mammary development. This study was conducted to determine the effect of ATRA on casein synthesis and fatty acid composition in MAC-T cells. METHODS:MAC-T cells were allowed to differentiate for 4 d, treated with ATRA (0, 1.0, 1.5, and 2.0 μM), and incubated for 3 d. We analyzed the fatty acid composition, the mRNA expression of casein and fatty acid synthesis-related genes, and the phosphorylation of casein synthesis-related proteins of MAC-T cells by gas chromatography, quantitative polymerase chain reaction, and western blotting, respectively. RESULTS:In MAC-T cells, ATRA increased the mRNA levels of αS1-casein and β-casein, janus kinase 2 (JAK2) and E74-like factor 5 of the signal transducer and activator of transcription 5 β (STAT5-β) pathway, ribosomal protein S6 kinase beta-1 (S6K1) and eukaryotic translation initiation factor 4E binding protein 1 of the mammalian target of rapamycin (mTOR) pathway, inhibited the mRNA expression of phosphoinositide 3-kinase and eukaryotic initiation factor 4E of the mTOR pathway, and promoted the phosphorylation of STAT5-β and S6K1 proteins. Additionally, ATRA increased the de novo synthesis of fatty acids, reduced the content of long-chain fatty acids, the ratio of monounsaturated fatty acids to saturated fatty acids (SFA), the ratio of polyunsaturated fatty acids (PUFA) to SFA, and the ratio of ω-6 to ω-3 PUFA. The mRNA levels of acetyl-CoA carboxylase 1, fatty acid synthase, lipoprotein lipase, stearoyl-CoA desaturase, peroxisome proliferator-activated receptor gamma, and sterol regulatory element-binding protein 1 (SREBP1) were enhanced by ATRA. CONCLUSION:ATRA promotes the synthesis of casein by regulating JAK2/STAT5 pathway and downstream mTOR signaling pathway, and it improves the fatty acid composition of MAC-T cells by regulating SREBP1-related genes.

Dataset Information

Investigations on the Effect of Fatty Acid Additives on Casein Micelles: Role of Ethylenic Unsaturation on the Interaction and Structural Diversity.

Publications

Investigations on the Effect of Fatty Acid Additives on Casein Micelles: Role of Ethylenic Unsaturation on the Interaction and Structural Diversity.

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