1
|
Cysteine residues are responsible for the sulfurous off-flavor formed in heated whey protein solutions. FOOD CHEMISTRY: MOLECULAR SCIENCES 2022; 5:100120. [PMID: 35865714 PMCID: PMC9294045 DOI: 10.1016/j.fochms.2022.100120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 05/30/2022] [Accepted: 07/09/2022] [Indexed: 10/25/2022]
|
2
|
Effect of solvent composition on the extraction of proteins from hemp oil processing stream. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2022; 102:6293-6298. [PMID: 35514139 PMCID: PMC9790205 DOI: 10.1002/jsfa.11979] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 04/29/2022] [Accepted: 05/05/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Hempseed meal, a by-product of the hempseed oil processing stream, is a potential alternative source for food proteins. Efficient extraction of proteins from hempseed meal is challenging owing to differences in the structure and solubility of various protein fractions present in the seed. In the present study, protein was extracted from hempseed meal using four different solvents, including aqueous NaOH, KOH, NaHCO3 and NaCl, at four different concentrations with the aim of improving the recovery of protein fractions rich in essential amino acids. RESULTS Extraction using alkaline solvents provided superior protein recovery (60-78%) compared with NaCl solution and control extractions (20-48% and 21%, respectively). The concentration of alkali or salt (0.25-1 mol L-1 ) had a minor but significant impact on the yield. Amino acid composition analysis revealed that hempseed meal contains 24% (54.5 ± 0.19 mg g-1 ) essential amino acids of total amino acids, and extraction with NaOH, KOH, NaHCO3 or NaCl did not improve the selective extraction of essential amino acids compared to control experiments. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis allowed the identification of edestin and albumin in the extracts obtained with NaHCO3 and NaCl solvents, with results further showing that the type of extraction solvent influences protein extraction selectivity. CONCLUSION Although alkali solvents provide superior extraction yields, extraction with water resulted in extracts containing the highest proportion of proteins bearing essential amino acids. According to the results of SDS-PAGE, extraction using alkali solvents induced protein crosslinking. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Collapse
|
3
|
A Pragmatic Perspective of the Initial Stages of the Contact Killing of Bacteria on Copper-Containing Surfaces. Appl Microbiol 2022. [DOI: 10.3390/applmicrobiol2030033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A consideration of the outer structures of Gram-positive and Gram-negative bacteria, and of the surface contaminants present on Cu-containing substrates, has led to the identification of Cu2O as a potent antimicrobial. In the presence of adsorbed water, the hydrated form ionizes to CuI-O−, which is capable of degrading the protective polysaccharide layer of the outer lipopolysaccharide membranes of Gram-negative bacteria; it is equally capable of attacking the peptidoglycan lattices present in both Gram-positive and Gram-negative bacteria. This Perspective underlines the importance of CuI-O− in the early stages of contact killing, and points to information, still lacking, that would optimize contact killing and lead to broader applications in the therapeutic management of bacterial infections.
Collapse
|
4
|
Comment on "High-Resolution Microscopical Studies of Contact Killing Mechanisms on Copper-Based Surfaces". ACS APPLIED MATERIALS & INTERFACES 2022; 14:16959-16960. [PMID: 35380799 DOI: 10.1021/acsami.2c03324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In the original paper, Chang and co-workers describe the contact killing of Bacillus subtilis, a Gram-positive bacterium, on copper-containing substrates and offer a mechanism for its accomplishment. The present Comment offers support for that mechanism and adds a necessary initial step, the degradation of the overlying peptidoglycan lattice. Degradation is necessary because the lattice is too thick, and its pores too small, for substrate-membrane contact without it. A suggestion is offered as to how degradation is accomplished.
Collapse
|
5
|
A Pragmatic Perspective of the Antibacterial Properties of Metal-Based Nanoparticles. NANOMATERIALS 2021; 11:nano11123214. [PMID: 34947563 PMCID: PMC8707375 DOI: 10.3390/nano11123214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/11/2021] [Accepted: 11/24/2021] [Indexed: 12/18/2022]
Abstract
A consideration of the antibacterial efficacy of metal-based nanoparticles, from the point of view of their physicochemical properties, suggests that such efficacy arises from the protein coronas that form around them, and that the contents of the coronas depend on the chemical groups found on the nanoparticle surfaces. We offer a new perspective and new insights, making use of our earlier observations of the physicochemical properties of nanoparticle surfaces, to propose that the nanoparticle serves as a mediator for the formation and activation of the protein corona, which attacks the bacterium. That is, the nanoparticle enhances the body’s natural defenses, using proteins present in body fluids.
Collapse
|
6
|
Effects of Protein-Derived Amino Acid Modification Products Present in Infant Formula on Metabolic Function, Oxidative Stress, and Intestinal Permeability in Cell Models. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:5634-5646. [PMID: 31017422 DOI: 10.1021/acs.jafc.9b01324] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Proteins present in infant formulas are modified by oxidation and glycation during processing. Modified amino acid residues released from proteins may be absorbed in the gastrointestinal tract, and pose a health risk to infants. In this study, the markers of glycation furosine (1.7-3.5 μg per milligram of protein) and Nε-(carboxymethyl)lysine (28-81 ng per milligram of protein) were quantitated in infant formulas. The effects of these species, and other amino acid modifications, at the levels detected in infant formulas, on 3T3-L1 (murine preadipocyte) and Caco-2 (human intestinal epithelial) cells were assessed. Incubation of 3T3-L1 cells for 48 h with amino acid side chain oxidation and glycation products (1 and 10 μM) resulted in a loss (up to 40%, p < 0.05) of cell thiols and decreased metabolic activity compared with those of the controls. In contrast, Caco-2 cells showed a stimulation (10-50%, p < 0.05) of cellular metabolism on exposure to these products for 24 or 48 h. A 28% ( p < 0.05) increase in protein carbonyls was detected upon incubation with 200 μM modified amino acids for 48 h, although no alteration in transepithelial electrical resistance was detected. Oxidation products were detected in the basolateral compartments of Caco-2 monolayers when modified amino acids were applied to the apical side, consistent with limited permeability (up to 3.4%) across the monolayer. These data indicate that modified amino acids present in infant formulas can induce effects on different cell types, with evidence of bioavailability and induction of cellular stress. This may lead to potential health risks for infants consistently exposed to high levels of infant formulas.
Collapse
|
7
|
Exploring the Identity of the General Base for a DNA Polymerase Catalyzed Reaction Using QM/MM: The Case Study of Human Translesion Synthesis Polymerase η. ACS Catal 2019. [DOI: 10.1021/acscatal.8b04889] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
|
8
|
The Collagen Suprafamily: From Biosynthesis to Advanced Biomaterial Development. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1801651. [PMID: 30126066 DOI: 10.1002/adma.201801651] [Citation(s) in RCA: 448] [Impact Index Per Article: 89.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 06/03/2018] [Indexed: 05/20/2023]
Abstract
Collagen is the oldest and most abundant extracellular matrix protein that has found many applications in food, cosmetic, pharmaceutical, and biomedical industries. First, an overview of the family of collagens and their respective structures, conformation, and biosynthesis is provided. The advances and shortfalls of various collagen preparations (e.g., mammalian/marine extracted collagen, cell-produced collagens, recombinant collagens, and collagen-like peptides) and crosslinking technologies (e.g., chemical, physical, and biological) are then critically discussed. Subsequently, an array of structural, thermal, mechanical, biochemical, and biological assays is examined, which are developed to analyze and characterize collagenous structures. Lastly, a comprehensive review is provided on how advances in engineering, chemistry, and biology have enabled the development of bioactive, 3D structures (e.g., tissue grafts, biomaterials, cell-assembled tissue equivalents) that closely imitate native supramolecular assemblies and have the capacity to deliver in a localized and sustained manner viable cell populations and/or bioactive/therapeutic molecules. Clearly, collagens have a long history in both evolution and biotechnology and continue to offer both challenges and exciting opportunities in regenerative medicine as nature's biomaterial of choice.
Collapse
|
9
|
The first report on the transition metal-free homocoupling of aryl halides in the presence of l-cysteine. NEW J CHEM 2018. [DOI: 10.1039/c8nj01518j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A green and efficient methodology for the coupling of aryl halides without the addition of a transition metal catalyst has been presented.
Collapse
|
10
|
|
11
|
Multifactorial level of extremostability of proteins: can they be exploited for protein engineering? Extremophiles 2017; 21:419-444. [PMID: 28283770 DOI: 10.1007/s00792-016-0908-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 12/19/2016] [Indexed: 12/20/2022]
Abstract
Research on extremostable proteins has seen immense growth in the past decade owing to their industrial importance. Basic research of attributes related to extreme-stability requires further exploration. Modern mechanistic approaches to engineer such proteins in vitro will have more impact in industrial biotechnology economy. Developing a priori knowledge about the mechanism behind extreme-stability will nurture better understanding of pathways leading to protein molecular evolution and folding. This review is a vivid compilation about all classes of extremostable proteins and the attributes that lead to myriad of adaptations divulged after an extensive study of 6495 articles belonging to extremostable proteins. Along with detailing on the rationale behind extreme-stability of proteins, emphasis has been put on modern approaches that have been utilized to render proteins extremostable by protein engineering. It was understood that each protein shows different approaches to extreme-stability governed by minute differences in their biophysical properties and the milieu in which they exist. Any general rule has not yet been drawn regarding adaptive mechanisms in extreme environments. This review was further instrumental to understand the drawback of the available 14 stabilizing mutation prediction algorithms. Thus, this review lays the foundation to further explore the biophysical pleiotropy of extreme-stable proteins to deduce a global prediction model for predicting the effect of mutations on protein stability.
Collapse
|
12
|
Heat-denaturation and aggregation of quinoa ( Chenopodium quinoa ) globulins as affected by the pH value. Food Chem 2016; 196:17-24. [DOI: 10.1016/j.foodchem.2015.08.069] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 08/07/2015] [Accepted: 08/18/2015] [Indexed: 10/23/2022]
|
13
|
Modifying the Cold Gelation Properties of Quinoa Protein Isolate: Influence of Heat-Denaturation pH in the Alkaline Range. PLANT FOODS FOR HUMAN NUTRITION (DORDRECHT, NETHERLANDS) 2015; 70:250-256. [PMID: 25986749 DOI: 10.1007/s11130-015-0487-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Heat-denaturation of quinoa protein isolate (QPI) at alkali pH and its influence on the physicochemical and cold gelation properties was investigated. Heating QPI at pH 8.5 led to increased surface hydrophobicity and decreases in free and bound sulfhydryl group contents. Heating at pH 10.5 caused a lesser degree of changes in sulfhydryl groups and surface hydrophobicity, and the resulting solutions showed drastically increased solubility. SDS PAGE revealed the presence of large aggregates only in the sample heated at pH 8.5, suggesting that any aggregates present in the sample heated at pH 10.5 were non-covalently bound and disintegrated in the presence of SDS. Reducing conditions partially dissolved the aggregates in the pH 8.5 heated sample indicating the occurrence of disulphide bonding, but caused no major alterations in the separation pattern of the pH 10.5 heated sample. Denaturation pH influenced the cold gelation properties greatly. Solutions heated at pH 8.5 formed a coarse coagulum with maximum G' of 5 Pa. Heat-denaturation at 10.5 enabled the proteins to form a finer and regularly structured gel with a maximum G' of 1140 Pa. Particle size analysis showed that the pH 10.5 heated sample contained a higher level of very small particles (0.1-2 μm), and these readily aggregated into large particles (30-200 μm) when pH was lowered to 5.5. Differences in the nature of aggregates formed during heating may explain the large variation in gelation properties.
Collapse
|
14
|
Control and role of pH in peptide–lipid interactions in oriented membrane samples. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:833-41. [DOI: 10.1016/j.bbamem.2014.12.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 12/01/2014] [Accepted: 12/04/2014] [Indexed: 12/22/2022]
|
15
|
|
16
|
Protein Modification During Ingredient Preparation and Food Processing: Approaches to Improve Food Processability and Nutrition. FOOD BIOPROCESS TECH 2014. [DOI: 10.1007/s11947-014-1326-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
17
|
|
18
|
Experimental investigation of egg ovalbumin scaling on heated stainless steel surface and scale-removal compared with that of whey protein. Colloids Surf B Biointerfaces 2013; 107:198-204. [DOI: 10.1016/j.colsurfb.2013.01.056] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 01/25/2013] [Accepted: 01/28/2013] [Indexed: 10/27/2022]
|
19
|
|
20
|
Effect of temperature, time and wheat gluten moisture content on wheat gluten network formation during thermomolding. J Cereal Sci 2011. [DOI: 10.1016/j.jcs.2011.08.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
21
|
Isolation of a thermostable variant of Lip2 lipase from Yarrowia lipolytica by directed evolution and deeper insight into the denaturation mechanisms involved. J Biotechnol 2011; 156:117-24. [DOI: 10.1016/j.jbiotec.2011.06.035] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Revised: 06/22/2011] [Accepted: 06/29/2011] [Indexed: 10/18/2022]
|
22
|
Cross-linking of wheat gluten proteins during production of hard pretzels. Amino Acids 2011; 42:2429-38. [DOI: 10.1007/s00726-011-1048-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 07/18/2011] [Indexed: 11/24/2022]
|
23
|
Proteomic analyses of corneal tissue subjected to alkali exposure. Invest Ophthalmol Vis Sci 2011; 52:1819-31. [PMID: 20861482 PMCID: PMC3101685 DOI: 10.1167/iovs.10-5472] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 08/10/2010] [Accepted: 08/25/2010] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To determine whether exposure to alkaline chemicals results in predictable changes in corneal protein profile. To determine whether protein profile changes are indicative of severity and duration of alkali exposure. METHODS Enucleated bovine and porcine (n = 59 each) eyes were used for exposure to sodium, ammonium, and calcium hydroxide, respectively. Eyes were subjected to fluorescein staining, 5-bromo-2'-deoxy-uridine (BrdU) labeling. Excised cornea was subjected to protein extraction, spectrophotometric determination of protein amount, dynamic light scattering and SDS-PAGE profiling, mass spectrometric protein identification, and iTRAQ-labeled quantification. Select identified proteins were subjected to Western blot and immunohistochemical analyses. RESULTS Alkali exposure resulted in lower protein extractability from corneal tissue. Elevated aggregate formation was found with strong alkali exposure (sodium hydroxide>ammonium, calcium hydroxide), even with a short duration of exposure compared with controls. The protein yield after exposure varied as a function of postexposure time. Protein profiles changed because of alkali exposure. Concentration and strength of the alkali affected the profile change significantly. Mass spectrometry identified 15 proteins from different bands with relative quantification. Plexin D1 was identified for the first time in the cornea at a protein level that was further confirmed by Western blot and immunohistochemical analyses. CONCLUSIONS Exposure to alkaline chemicals results in predictable and reproducible changes in corneal protein profile. Stronger alkali, longer durations, or both, of exposure resulted in lower yields and significant protein profile changes compared with controls.
Collapse
|
24
|
The kinetics of β-elimination of cystine and the formation of lanthionine in gliadin. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:10761-10767. [PMID: 20836554 DOI: 10.1021/jf102575r] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
When gliadin, a mixture of wheat storage proteins containing only intramolecular disulfide (SS) bonds, is heated at high temperatures and preferably at alkaline pH, the SS bonds are cleaved by β-elimination reactions leading to decreased cystine levels and the generation of dehydroalanine (DHA) and free sulfhydryl (SH) groups. DHA and the free SH group of cysteine can further react to form the irreversible cross-link lanthionine (LAN). The kinetics of this reaction were studied by heating model systems containing gliadin at different pH values (pH 6.0, 8.0 and 11.0) at temperatures up to 120 °C. Multiresponse modeling was applied to simultaneously describe the course of the reaction partners, intermediates and products. The estimated kinetic parameters indicate that the reaction rate constant for the elimination reaction increases with temperature and pH. Moreover, the predominant reaction consuming the intermediary DHA is the cross-link with cysteine to form LAN following second-order reaction kinetics. The corresponding reaction rate constant is less dependent on temperature and pH. Use of the proposed kinetic model to estimate reaction product concentrations in cereal-based foods allowed us to conclude that the β-elimination reaction may be less important during, e.g., bread making, but may well contribute to gluten network formation during the production of soft wheat products. It may also well be relevant in the production of bioplastics made from gluten.
Collapse
|
25
|
Rapid and irreversible reduction of protein disulfide bonds. Anal Biochem 2010; 405:67-72. [PMID: 20488157 DOI: 10.1016/j.ab.2010.05.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 05/05/2010] [Accepted: 05/12/2010] [Indexed: 11/29/2022]
Abstract
This report describes the development of a method that enables a rapid (less than 20s), quantitative, and irreversible reduction and inactivation of disulfide-containing proteins at room temperature (20 to 25 degrees C). The formula comprises the ingredients of optimized concentrations of denaturant, reductant, and hydroxide ion. The novelty of this formula is the application of a potent hydroxide ion in the concoction. The component of hydroxide ion serves two major functions. (1) It accelerates the cleavage of disulfide bonds mediated by the reducing agent and denaturant, leading to an instant and quantitative reduction of disulfide proteins. (2) It triggers a rapid covalent destruction of sulfhydryl groups and disulfide bonds via the mechanism of base-catalyzed beta-elimination, thus leading to the irreversible and permanent abolition of disulfide bonds. The usefulness of this formula has been demonstrated here with the effective and rapid reduction of numerous highly stable disulfide-containing proteins, including cardiotoxin and prion aggregates.
Collapse
|
26
|
Glutathione-Mediated Biodegradable Polyurethanes Derived from l-Arabinitol. Biomacromolecules 2009; 11:269-76. [DOI: 10.1021/bm9011216] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
27
|
Quality specifications for peptide drugs: a regulatory-pharmaceutical approach. J Pept Sci 2009; 15:697-710. [DOI: 10.1002/psc.1167] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
28
|
Assessment of antibody fragmentation by reversed-phase liquid chromatography and mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2008; 876:13-23. [DOI: 10.1016/j.jchromb.2008.10.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 09/29/2008] [Accepted: 10/08/2008] [Indexed: 10/21/2022]
|
29
|
|
30
|
Results and reliability of protein quantification for two-dimensional gel electrophoresis strongly depend on the type of protein sample and the method employed. Proteomics 2008; 8:3389-96. [DOI: 10.1002/pmic.200800236] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
31
|
|
32
|
Polyelectrolyte screening effects on the dissolution of whey protein gels at high pH conditions. Food Hydrocoll 2007. [DOI: 10.1016/j.foodhyd.2006.09.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
33
|
Methods for the regulation of the functional properties of isolated myofibrillar proteins in order to expand their use as foodstuffs. RUSSIAN CHEMICAL REVIEWS 2007. [DOI: 10.1070/rc1989v058n12abeh003504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
34
|
Peptic digestion of β-casein. J Chromatogr A 2007; 1166:108-15. [PMID: 17720176 DOI: 10.1016/j.chroma.2007.08.015] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 08/01/2007] [Accepted: 08/02/2007] [Indexed: 11/21/2022]
Abstract
Numerous peptides obtained by enzymatic digestion of food proteins have been reported to exhibit biological activities. In this study, the focus was placed on peptides of beta-casein from bovine milk after a gastro-analogous in vitro digestion with pepsin, a protease with broad specificity. In order to study the time course of the digestion, the process was stopped after specific times and the samples were subjected to HPLC separation followed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) and nanoelectrospray (nanoESI) quadrupole time-of-flight (qTOF) mass spectrometry. A combined sequencing approach using de novo interpretation and databases was employed. Overall, 100% of the beta-casein sequence was covered by identifying 125 peptides of 4-84 residues in length, including 3 phosphorylated species. The results show that the peptic hydrolysis starts at the C-terminus of the protein. The release of known bioactive peptides from beta-casein following the peptic digestion under simulated gastric conditions is unlikely with a few exceptions. Furthermore, an amino acid variation was found, providing evidence for the existence of an additional genetic variant of beta-casein.
Collapse
|
35
|
The pH Threshold in the Dissolution of β-Lactoglobulin Gels and Aggregates in Alkali. Biomacromolecules 2007; 8:1162-70. [PMID: 17378604 DOI: 10.1021/bm061100l] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The existence of a practical minimum pH for the dissolution of heat-induced whey gels in alkaline solutions has been studied using beta-lactoglobulin (betaLg) as a model protein. A sharp transition in solubility was observed between pH 11 and 12; this transition shifts to higher pHs for gels formed at higher temperatures and for longer gelling times. The breakdown reactions of heat-induced aggregates in alkali were monitored with size exclusion chromatography. The destruction of large aggregates was faster at higher pH and also showed a transition between pH 11 and 12. Using tryptophan fluorescence and near- and far-UV circular dichroism, this transition was assigned to the base-induced denaturation observed in solutions of aggregates (pK 11.53). It is suggested that the high protein repulsion caused by the large number of charges at pH > 11.5 drives the unfolding of the protein and the disruption of the intermolecular noncovalent bonds. Concentrated urea and GuHCl were found to be less effective than a pH 12 solution in destroying large aggregates. Aggregates formed for a long time (80 degrees C for 24 h) contained a larger number of intermolecular disulfide bonds that hinder the dissolution process. Gels formed at low temperatures (65 degrees C for 60 min), with fewer intermolecular noncovalent bonds, showed a similar solubility-pH profile to that observed for the base-induced denaturation of unheated beta-lactoglobulin (betaLg) (pK 10.63).
Collapse
|
36
|
Probing The Mechanisms Limiting Dissolution of Whey Protein Gels During Cleaning. FOOD AND BIOPRODUCTS PROCESSING 2006. [DOI: 10.1205/fbp06021] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
37
|
Synthesis and chemical stability of a disulfide bond in a model cyclic pentapeptide: cyclo(1,4)-Cys-Gly-Phe-Cys-Gly-OH. J Pharm Sci 2006; 95:2222-34. [PMID: 16883561 DOI: 10.1002/jps.20701] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Many cyclic peptides are formed using a disulfide bond to increase their conformational rigidity; this provides receptor selectivity and increased potency. However, degradation of the disulfide bond in formulation can lead to a loss of structural stability and biological activity of the peptide. Therefore, the objective of this study was to study the stability of peptide 1 (cyclo(1,4)-Cys-Gly-Phe-Cys-Gly-OH). This cyclic peptide was synthesized using Boc strategy via solution-phase peptide synthesis and purified using semi-preparative HPLC. The accelerated stability studies of the cyclic peptide were conducted in buffer solutions at pH 1.0-11.0 with controlled ionic strengths at 70 degrees C. The pH-rate profile shows that the peptide has an optimal stability around pH 3.0 with a V-shape between pH 1.0 and 5.0. Two small plateaus are observed at pH 5.0-7.0 and pH 8.0-10.0, indicating hydrolysis on different ionized forms of the cyclic peptide. One product was observed at acidic pH due to peptide bond hydrolysis at Gly2-Phe3. The number of degradation products increases as the pH increases from neutral to basic, and most of the degradation products at neutral and basic pH are derived from the degradation at the disulfide bond.
Collapse
|
38
|
Effect of gel structure on the dissolution of heat-induced beta-lactoglobulin gels in alkali. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2006; 54:5437-44. [PMID: 16848529 DOI: 10.1021/jf0605650] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The dissolution of heat-induced beta-lactoglobulin (betaLg) gels in alkaline solution plays an important role in the cleaning-in-place of fouled dairy and other food plants. The dissolution behavior is strongly influenced by the conditions under which the gel is formed. At low alkaline pH values (<13), the dissolution rate constant kg' decreases with longer gelation time and higher temperature. An inverse relationship is observed between the kg' value and the amount of covalently cross-linked proteins in the gel, which is mainly due to disulfide bonds. beta-Elimination kinetics of intramolecular cystines in betaLg have been used to estimate the amount of intermolecular disulfide bonds that are cleaved during dissolution. The results call into question current dissolution models for these systems based on external mass transfer through the fluid next to the swollen gel. At low temperatures, the amount of disulfide cleavage is estimated to be small, indicating that dissolution is likely to involve the (slow) disengagement of large protein clusters, analogous to the dissolution of synthetic polymers.
Collapse
|
39
|
Suppression of sodium dodecyl sulfate–polyacrylamide gel electrophoresis sample preparation artifacts for analysis of IgG4 half-antibody. Anal Biochem 2006; 353:204-8. [PMID: 16564018 DOI: 10.1016/j.ab.2006.02.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Revised: 02/15/2006] [Accepted: 02/20/2006] [Indexed: 10/24/2022]
Abstract
Human IgG4 subtype antibodies have often been reported to have a significant portion (5-50%) of a heavy chain-light chain dimer ("half-antibody") on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), in which the heavy chain is not covalently linked through the hinge disulfides to another heavy chain. We demonstrate here that there can be artifactual sources of half-antibody. One occurred during SDS-PAGE sample preparation where rapid disulfide scrambling was initiated by preexisting free sulfhydryls in the monoclonal antibody (mAb) and by free sulfhydryl produced by destruction of disulfide bonds during heating. Inclusion of N-ethylmaleimide in the sample buffer prevented the disulfide scrambling. Presumably, cyclization of the flexible IgG4 hinge during this disulfide scrambling leads to the preferential separation of heavy chains. A second condition producing half-antibody was reoxidation after exposure to reductant, where 46% of the antibody was trapped in the intrachain disulfide form. The amount of half-antibody was reduced to 4% by reoxidation in the presence of a mixture of oxidized and reduced glutathione. When the improved sample preparation conditions were used, IgG4 mAb freshly isolated from cells contained 4.5-15% half-antibody, indicating that equilibration of the interchain and intrachain hinge disulfide pairing was not always attained in cells.
Collapse
|
40
|
Characterisation and foaming properties of hydrolysates derived from rapeseed isolate. Colloids Surf B Biointerfaces 2006; 49:40-8. [PMID: 16581234 DOI: 10.1016/j.colsurfb.2006.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Accepted: 02/04/2006] [Indexed: 11/21/2022]
Abstract
Two hydrolysis methods used to obtain rapeseed isolate derivates were compared: chemical hydrolysis performed under alkaline conditions and pepsic proteolysis performed under acidic conditions. The mean molecular weights obtained for the hydrolysates varied from 26 to 2.5 kDa, depending on the level of hydrolysis. Further characterisation showed that, at the same level of hydrolysis, the chemical hydrolysates differed by their charges and hydrophobicity from those derived from enzymatic digestion. Analysis of the foaming properties showed, for both cases, that a limited degree of hydrolysis, around 3%, was sufficient to optimise the foaming properties of the isolate despite the different physicochemical properties of the peptides generated. The study of foaming properties at basic, neutral and acidic pHs showed that the hydrolysate solutions yielded dense foams which drained slowly and which maintained a very stable volume under the three pH conditions tested.
Collapse
|
41
|
|
42
|
Enrichment of phosphorylated proteins and peptides from complex mixtures using metal oxide/hydroxide affinity chromatography (MOAC). Proteomics 2005; 5:4389-97. [PMID: 16222723 DOI: 10.1002/pmic.200402049] [Citation(s) in RCA: 260] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A novel method termed metal oxide affinity chromatography (MOAC) of enriching for phosphorylated proteins and peptides based on the affinity of the phosphate group for Al(OH)(3) is presented here. When compared to commercial phosphoprotein-enrichment kits, this method is more selective, more cost effective and easily applicable to method optimization. The use of glutamic and aspartic acid in the loading buffer significantly enhances selectivity. Standard protein mixtures and complex Arabidopsis thaliana leaf protein extracts were tested for efficacy of enrichment. The method can be applied to proteins extracted using either mild or denaturing conditions. The same Al(OH)(3) material is suitable for the enrichment of phosphopeptides out of a tryptic digest of alpha-casein. Peptide phosphorylation was revealed by beta-elimination of phosphate groups. Enrichment and in vivo phosphorylation of A. thaliana leaf proteins were confirmed with Pro-Q diamond stain. Several of the phosphoprotein candidates that were identified by MS are known to be phosphorylated in vivo in other plant species.
Collapse
|
43
|
Colorimetric Analysis of Protein Sulfhydyl Groups in Milk: Applications and Processing Effects. Crit Rev Food Sci Nutr 2005; 45:1-23. [PMID: 15730186 DOI: 10.1080/10408690590900126] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Methods for protein sulfhydryl (SH) group analysis in food systems have been largely overlooked. Nevertheless, changes in SH group concentration affect both physical and nutritional characteristics of high protein foods and ingredients. Food scientists and technologists require improved understanding of protein SH chemistry in order to design processes that minimize loss of thiol groups. This article surveys colorimetric methods for food protein SH group analysis with applications to fluid milk and dried milk powder. Most colorimetric assays (chloromeribenzoate, pyridine disulfide, Nitrobenzo-2-oxa-1,3-diazole, papain reactivation assay, etc.) were found to be inferior to the Ellman method based on the use of 5,5'dithio (bis-2 nitro benzoic acid). Techniques for SH group analysis in fluid milk and dried milk powder are described, along with typical results, their interpretations, and current research related to processing effects and the role of milk SH content on a wider range of technological issues, such as development of cooked flavors, fouling and cleaning of plate heat exchanges, protein-protein interactions, and the storage stability. Finally, a number of areas requiring further research are presented.
Collapse
|
44
|
An integrated strategy for identification and relative quantification of site-specific protein phosphorylation using liquid chromatography coupled to MS2/MS3. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2005; 19:3626-32. [PMID: 16287031 DOI: 10.1002/rcm.2236] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Reversible and differential multisite protein phosphorylation is an important mechanism controlling the activity of cellular proteins. Here we describe a robust and highly selective approach for the identification and relative quantification of site-specific phosphorylation events. This integrated strategy has three major parts: visualisation of phosphorylated proteins using fluorescently stained polyacrylamide gels, determination of the phosphorylation site(s) using automatic MS3 triggered by the loss of phosphoric acid, and relative quantification of phosphorylation by integrating MS2- and MS3-extracted ion traces using a fast-scanning, linear ion trap mass spectrometer. As a test case, recombinant sucrose-phosphate synthase (SPS) from Arabidopsis thaliana (At5g1110) was used for identification and quantification of site-specific phosphorylation. The identified phosphorylation site of the actively expressed protein coincides with the major regulatory in vivo phosphorylation site in spinach SPS. Site-specific differential in vitro phosphorylation of native protein was demonstrated after incubation of the recombinant protein with cold-adapted plant leaf extracts from A. thaliana, suggesting regulatory phosphorylation events of this key enzyme under stress response.
Collapse
|
45
|
|
46
|
Abstract
Alkaline-induced beta-elimination of phosphate from phosphoserine and phosphothreonine residues followed by addition of an affinity tag has recently been pursued as a strategy for enriching phosphorylated species from complex mixtures. Here we report the use of an introduced thiol tag as the ligand for affinity purification via disulfide exchange with an activated thiol resin and the development of a protocol to improve the sensitivity considerably over previous reports (i.e., to subpicomole levels.) During our experiments, we observed a side reaction in which water was eliminated from unmodified serine residues. This side reaction resulted in the introduction of the affinity tag into unphosphorylated proteins, confounding attempts to specifically purify phosphoproteins from mixtures. Unchecked, this side reaction will also prevent application of the beta-elimination strategy to phosphopeptide samples where the phosphorylated species are minor components (i.e., most current phosphoproteomics applications). Quantitation of the side reaction products using three synthetic unphosphorylated peptides showed varying conversion efficiencies; at maximum, 1.7% of unphosphorylated peptide was converted to the affinity-tagged form. Inclusion of EDTA into the reaction reduced the side reaction but also greatly reduced the conversion efficiency of one of the phosphoserine residues of ovalbumin, suggesting a role for trace metal ions in the beta-elimination chemistry. Despite the presence of the side reaction, the affinity strategy was shown to be effective at enriching phosphopeptides from fairly complex peptide mixtures. The strategy was applied to the analysis of in vitro phosphorylation of bovine synapsin I by Ca(2+)/calmodulin-dependent kinase II, resulting in the identification of four phosphorylation sites, two of which have not been previously reported.
Collapse
|
47
|
Cleaning Rate in the Uniform Cleaning Stage for Whey Protein Gel Deposits. FOOD AND BIOPRODUCTS PROCESSING 2002. [DOI: 10.1205/096030802321154727] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
48
|
|
49
|
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometric observation of a peptide triplet induced by thermal cleavage of cystine. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2001; 15:2296-2300. [PMID: 11746896 DOI: 10.1002/rcm.509] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Heat-induced (90 degrees C, 30 min) beta-elimination of a cystine residue leads to cleavage of a disulfide bond and produces a set of three peptides with a cysteine residue, a thiocysteine residue (+32Da), and a dehydroalanine residue (-34Da). This characteristic feature was observed from somatostatin and insulin by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Mass spectrometric observation of this triplet is useful in identifying the presence of a cystine residue in a peptide, and could assist mass spectrometric identification of the peptide from a database.
Collapse
|
50
|
Separation and detection techniques for peptides and proteins in stability research and bioanalysis. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2000; 742:401-9. [PMID: 10901145 DOI: 10.1016/s0378-4347(00)00198-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this paper, a brief overview of the most commonly used methods for the separation and analysis of peptides and proteins in stability and bioanalysis studies is presented. To investigate the physical stability of peptides and proteins, size-exclusion chromatography and electrophoretic separation techniques are being used, apart from several other methods. To determine the chemical stability of these compounds, separation systems are also important, with informative detection modes, such as various spectroscopic detections, electrochemical detection and mass spectrometric detection. For the bioanalysis of peptides, separation is the most important factor, while the detection must be done at the highest possible level of sensitivity.
Collapse
|