Effect of pH and Glucose on the Stability of α-lactalbumin

Velusamy, Vijayalakshmi; Palaniappan, L.

doi:10.1007/s11483-015-9423-2

Cited by 16 publications

(10 citation statements)

References 24 publications

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“…Dietary proteins have intrinsic characteristics that make them more stable under certain digestion conditions which in turn may also affect their susceptibility to pepsin, trypsin and chymotrypsin degradation. For example, α-La contains 4 pairs of disulfide bonds which should make it more stable, yet it unfolds at pH 2, permitting greater accessibility for digestive proteases [39]. This is in stark contrast to β-Lg, which contains only one pair of disulfide bonds yet retains its native conformation at pH 1 [40].…”

Section: Discussionmentioning

confidence: 99%

Presence of small resistant peptides from new in vitro digestion assays detected by liquid chromatography tandem mass spectrometry: An implication of allergenicity prediction of novel proteins?

Wang

Edrington

et al. 2020

PLoS ONE

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The susceptibility of newly expressed proteins to digestion by gastrointestinal proteases (e.g., pepsin) has long been regarded as one of the important endpoints in the weight-of-evidence (WOE) approach to assess the allergenic risk of genetically modified (GM) crops. The European Food Safety Authority (EFSA) has suggested that current digestion study protocols used for this assessment should be modified to more accurately reflect the diverse physiological conditions encountered in human populations and that the post-digestion analysis should include analytical methods to detect small peptide digestion products.The susceptibility of two allergens (beta-lactoglobin (β-Lg) and alpha-lactalbumin (α-La)) and two non-allergens (hemoglobin (Hb) and phosphofructokinase (PFK)) to proteolytic degradation was investigated under two pepsin digestion conditions (optimal pepsin digestion condition: pH 1.2, 10 U pepsin/μg test protein; sub-optimal pepsin digestion condition: pH 5.0, 1 U pepsin/10 mg test protein), followed by 34.5 U trypsin/mg test protein and 0.4 U chymotrypsin/ mg test protein digestion in the absence or presence of bile salts. All samples were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in conjunction with Coomassie Blue staining and, in parallel, liquid chromatography tandem mass spectrometry (LC-MS) detection. The results provide following insights: 1) LC-MS methodology does provide the detection of small peptides; 2) Peptides are detected in both allergens and non-allergens from all digestion conditions; 3) No clear differences among the peptides detected from allergen and non-allergens; 4) The differences observed in SDS-PAGE between the optimal and sub-optimal pepsin digestion conditions are expected and align with kinetics and properties of the specific enzymes; 5) The new methodology with new digestion conditions and LC-MS detection does not provide any differentiating information for prediction whether a protein is an allergen. The classic pepsin resistance assay remains the most useful assessment of the potential exposure of an intact newly expressed protein as part of product safety assessment within a WOE approach.

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Section: Discussionmentioning

confidence: 99%

Presence of small resistant peptides from new in vitro digestion assays detected by liquid chromatography tandem mass spectrometry: An implication of allergenicity prediction of novel proteins?

Wang

Edrington

et al. 2020

PLoS ONE

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“…In addition to many studies available in literature, one of our earlier works [3] reassures the role of pH and cosolvent on the stability of α-LA structure. The work cited was for α-lactalbumin normal sized protein particles dissolved in phosphate buffer and glucose cosolvent.…”

Section: Introductionmentioning

confidence: 91%

Affinity study of -lactalbumin nanoparticles in a mixed solvent environment using Laplace transform technique

Kavitha¹,

Palaniappan²

2022

Bull. Chem. Soc. Eth.

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ABSTRACT. Effect of pH and cosolvent on the stabilization of protein structure is a well established study in protein or food science. Of the various interesting applications of protein nanoparticles, making it as a drug or bioactive compound carrier is of vital importance. This application of protein nanoparticle demands the affinity priority of protein with the available components of the medium. The basis of such studies lies in the synthesis of such protein nanoparticles and their characterizations. Secondly the knowledge of priority in affinity of protein to a particular solvent is essential. On this basis, the present work deals with the ultrasonic analysis of hydophobic interactions exhibited by the α-lactalbumin nanoparticle synthesised by heat treatment using acetone as desolvating agent. In order to enrich the variations in hydrophobicity, pH and cosolvent (fructose) are included in the study. The results are compared with one of our earlier work and are interpreted in terms of the interactions existing among the components and the evolved discussions reveal that the bulk nature of the medium is controlled by the existing hydrophobicity interactions. Further, as a novel attempt, the preference of protein particle to interact with a particular solvent in mixed solvent environment is elucidated using Laplace transform technique. This approach is expected to torch light in protein science in fixing the most desirable solvent in mixed solvent environment. KEY WORDS: a-Lactalbumin, Fructose, Laplace Transform, Diffusion, Hydrophobic interactions Bull. Chem. Soc. Ethiop. 2021, 35(3), 659-668. DOI: https://dx.doi.org/10.4314/bcse.v35i3.16

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“…Protein study using ultrasonic techniques is an established attempt for resourceful information about the functional and structural features (Lin et al 2002, Velusamy andPalaniappan 2016). Various investigators (Hakin et al 1994, Zhang et al Sustainability, Agri, Food and Environmental Research, (ISSN: 0719-3726), X(X), 202X http://dx.doi.org/10.7770/safer-V0N0-art2231 3 3 2015, Kanjilal 2003) have used such techniques at different pH environments.…”

Section: Introductionmentioning

confidence: 99%

“…Various investigators (Hakin et al 1994, Zhang et al Sustainability, Agri, Food and Environmental Research, (ISSN: 0719-3726), X(X), 202X http://dx.doi.org/10.7770/safer-V0N0-art2231 3 3 2015, Kanjilal 2003) have used such techniques at different pH environments. Already we have made an extensive ultrasonic study on ovalbumin but with glucose (Velusamy and Palaniappan 2016) as cosolvent. Intermolecular free length and acoustic impedance were used by Aashees Awasthi and Shukla (2003) to explore the inertial and elastic properties of the proteins.…”

Section: Introductionmentioning

confidence: 99%

Response of Ovalbumin to Fructose Addition and pH Variations - Ultrasonic and FTIR Study

Palaniappan¹,

Kavitha²

2021

Sust. Agric. Food Env. Res.

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Main aim of this work is to understand how the protein ovalbumin is affected by the presence of cosolvent and variations in pH of the medium. The addition of cosolvent in many cases is found to control the extent of denaturation and pH is one of the main sources of denaturant of proteins. In this work, keeping fructose solution as cosolvent and pH of the solution as main variable, the extent of denaturation is analysed by ultrasonic methods and are further confirmed by FTIR amide-I second derivative spectra at 303 K. Obtained results shows that denaturation is sensitive to pH, however, acidic and alkaline behave totally in a different way. It was found that the impact of alkaline pH produces lesser denaturation and is slower whereas the impact of acidic pH is specific and instantaneous. Ultrasonic analysis shows that pH variation can denature the protein whereas the addition of cosolvent supports renaturation. FTIR spectra were recorded for the experimental samples from which the second derivative curve fitted spectra were constructed using Origin program. Quantitative assignment of peaks and the variations in cumulative areas calculated for the structures like α-helix, β-sheets etc confirms the observations of ultrasonic analysis that the pH variations aid in denaturation whereas the cosolvent supports the renaturation of protein.

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Effect of pH and Glucose on the Stability of α-lactalbumin

Cited by 16 publications

References 24 publications

Presence of small resistant peptides from new in vitro digestion assays detected by liquid chromatography tandem mass spectrometry: An implication of allergenicity prediction of novel proteins?

Presence of small resistant peptides from new in vitro digestion assays detected by liquid chromatography tandem mass spectrometry: An implication of allergenicity prediction of novel proteins?

Affinity study of -lactalbumin nanoparticles in a mixed solvent environment using Laplace transform technique

Response of Ovalbumin to Fructose Addition and pH Variations - Ultrasonic and FTIR Study

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