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Optimization of Selective Hydrolysis of Cruciferins for Production of Potent Mineral Chelating Peptides and Napins Purification to Valorize Total Rapeseed Meal Proteins. Foods 2022; 11:foods11172618. [PMID: 36076804 PMCID: PMC9455892 DOI: 10.3390/foods11172618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/18/2022] [Accepted: 08/26/2022] [Indexed: 11/17/2022] Open
Abstract
Preventing oxidation and microbial spoilage are both major concerns in food industries. In this context, this study aimed to valorize the total rapeseed meal proteins with controlled enzymatic proteolysis to generate potent mineral-chelating peptides from cruciferins while keeping intact the antimicrobial napins. Implementation of proteolysis of total rapeseed protein isolate with the Prolyve® enzyme highlighted an interesting selective hydrolysis of the cruciferins. Hence, the mechanism of this particular hydrolysis was investigated through a Design of Experiments method to obtain a model for the prediction of kinetics (cruciferin degradation and napin purity) according to the operating conditions applied. Then, multicriteria optimization was implemented to maximize the napin purity and yield while minimizing both enzymatic cost and reaction time. Antioxidant assays of the peptide fraction obtained under the optimal conditions proved the high metal-chelating activity preservation (EC50 = 247 ± 27 µg) for more than three times faster production. This fraction might counteract lipid oxidation or serve as preventing agents for micronutrient deficiencies, and the resulting purified napins may have applications in food safety against microbial contamination. These results can greatly help the development of rapeseed meal applications in food industries.
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Combined Effect of Extraction and Purification Conditions on Yield, Composition and Functional and Structural Properties of Lupin Proteins. Foods 2022; 11:foods11111646. [PMID: 35681397 PMCID: PMC9180897 DOI: 10.3390/foods11111646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 05/14/2022] [Accepted: 05/20/2022] [Indexed: 11/16/2022] Open
Abstract
Lupin meal presents great potential as an alternative plant-based source of proteins for human nutrition. In the present work, different conditions of extraction and purification were evaluated for production of lupin protein isolates. The results showed that the protein extraction yield was comparable at acidic and conventionally used alkaline extraction pH (37% vs. 40–45%, respectively). Proteins extracted were principally composed of globulins. The ionic strength negatively impacted the protein extractability at pH 2, whereas no significant differences were observed between extractions at 20 to 50 °C. The selected extraction conditions (pH 2 and 7) combined with purification by isoelectric precipitation or ultrafiltration process generated the isolate-grade products. Interestingly, further characterization revealed a partial denaturation of proteins extracted at pH 2 resulting in loss of protein solubility at pH 6 and 7 (10–50%), modifications in secondary structure, lower thermal stability, and formation of protein aggregates. However, foaming and emulsifying properties were generally similar for almost all lupin isolates. Further investigation might be of interest with regard to the extraction behaviours and structural and functional properties of specific lupin protein fractions.
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Thery T, Lynch KM, Zannini E, Arendt EK. Isolation, characterisation and application of a new antifungal protein from broccoli seeds – New food preservative with great potential. Food Control 2020. [DOI: 10.1016/j.foodcont.2020.107356] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Rahman M, Baten A, Mauleon R, King GJ, Liu L, Barkla BJ. Identification, characterization and epitope mapping of proteins encoded by putative allergenic napin genes from Brassica rapa. Clin Exp Allergy 2020; 50:848-868. [PMID: 32306538 DOI: 10.1111/cea.13612] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 03/25/2020] [Accepted: 04/13/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND Brassica rapeseed crops contain high concentrations of oil in the seed. The remaining meal, following oil extraction, has a high protein content, but is of low value due to the presence of high amounts of napin seed storage proteins. These 2S albumin-like proteins are difficult to digest and have been identified as major allergens in humans. OBJECTIVE To comprehensively characterize the napin gene (NG) family in Brassica rapa and to gain an understanding of the structural basis of allergenicity of the expressed proteins. METHODS To identify candidate napin genes in B rapa, 2S albumin-like napin genes of Arabidopsis thaliana were used as query sequences to search for similarity against the B rapa var. pekinensis Chiifu-401 v2 and the var. trilocularis R-o-18 v1.5 genomes. Multiple sequence alignment (MSA) and epitope modelling was carried out to determine structural and evolutionary relationships of NGs and their potential allergenicity. RESULTS Four candidate napin genes in R-o-18 and ten in Chiifu-401 were identified with high sequence similarity to A thaliana napin genes. Multiple sequence alignment revealed strong conservation among the candidate genes. An epitope survey indicated high conservation of allergenic epitope motifs with known 2S albumin-like allergens. CONCLUSION Napin is thought to be responsible for a high prevalence of food allergies. Characterization of the napin gene family in B rapa will give important insight into the protein structure, and epitope modelling will help to advance studies into allergenicity including the development of precise diagnostic screenings and therapies for this potential food allergy as well as the possible manipulation of napin levels in the seed by gene editing technology.
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Affiliation(s)
- Mahmudur Rahman
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia
| | - Abdul Baten
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia.,Grasslands Research Centre, AgResearch Ltd, Palmerston North, New Zealand
| | - Ramil Mauleon
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia
| | - Graham J King
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia
| | - Lei Liu
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia
| | - Bronwyn J Barkla
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia
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Xu F, Yao Y, Xu X, Wang M, Pan M, Ji S, Wu J, Jiang D, Ju X, Wang L. Identification and Quantification of DPP-IV-Inhibitory Peptides from Hydrolyzed-Rapeseed-Protein-Derived Napin with Analysis of the Interactions between Key Residues and Protein Domains. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:3679-3690. [PMID: 30854852 DOI: 10.1021/acs.jafc.9b01069] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Previously reported peptides derived from napin of rapeseed ( Brassica napus) have been shown to inhibit DPP-IV in silico. In the present study, napin extracted from rapeseed was hydrolyzed by commercial enzymes and filtered by an ultrafiltration membrane. The napin hydrolysate was then purified by a Sephadex G-15 gel-filtration column and preparative RP-HPLC. A two-enzyme-combination approach with alcalase and trypsin was the most favorable in terms of the DPP-IV-inhibitory activity (IC50 = 0.68 mg/mL) of the napin hydrolysate. Three peptides and one modified peptide (pyroglutamate mutation at the N-terminus) were identified using HPLC-triple-TOF-MS/MS. DPP-IV-inhibitory activity and the types of enzyme inhibition were also determined. Meanwhile, key residues associated with the interactions between the selected peptides and DPP-IV were investigated by molecular docking. IPQVS has key amino acid residues (Tyr547, Glu205, and Glu206) that are consistent with Diprotin A. ELHQEEPL could form a better covalent bond with Arg358 in the S3 pocket of DPP-IV.
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Affiliation(s)
- Feiran Xu
- National Engineering Laboratory for Cereal Fermentation Technology, State Key Laboratory of Food Science and Technology, School of Food Science and Technology , Jiangnan University , 1800 Lihu Road , Wuxi , Jiangsu 214122 , People's Republic of China
| | - Yijun Yao
- National Engineering Laboratory for Cereal Fermentation Technology, State Key Laboratory of Food Science and Technology, School of Food Science and Technology , Jiangnan University , 1800 Lihu Road , Wuxi , Jiangsu 214122 , People's Republic of China
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing , Nanjing University of Finance and Economics , Number 3 Wenyuan Road , Nanjing , Jiangsu 210023 , People's Republic of China
| | - Xiaoying Xu
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing , Nanjing University of Finance and Economics , Number 3 Wenyuan Road , Nanjing , Jiangsu 210023 , People's Republic of China
| | - Mei Wang
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing , Nanjing University of Finance and Economics , Number 3 Wenyuan Road , Nanjing , Jiangsu 210023 , People's Republic of China
| | - Mengmeng Pan
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing , Nanjing University of Finance and Economics , Number 3 Wenyuan Road , Nanjing , Jiangsu 210023 , People's Republic of China
| | - Shengyang Ji
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing , Nanjing University of Finance and Economics , Number 3 Wenyuan Road , Nanjing , Jiangsu 210023 , People's Republic of China
| | - Jin Wu
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing , Nanjing University of Finance and Economics , Number 3 Wenyuan Road , Nanjing , Jiangsu 210023 , People's Republic of China
| | - Donglei Jiang
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing , Nanjing University of Finance and Economics , Number 3 Wenyuan Road , Nanjing , Jiangsu 210023 , People's Republic of China
| | - Xingrong Ju
- National Engineering Laboratory for Cereal Fermentation Technology, State Key Laboratory of Food Science and Technology, School of Food Science and Technology , Jiangnan University , 1800 Lihu Road , Wuxi , Jiangsu 214122 , People's Republic of China
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing , Nanjing University of Finance and Economics , Number 3 Wenyuan Road , Nanjing , Jiangsu 210023 , People's Republic of China
| | - Lifeng Wang
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing , Nanjing University of Finance and Economics , Number 3 Wenyuan Road , Nanjing , Jiangsu 210023 , People's Republic of China
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Expeller Barrel Dry Heat and Moist Heat Pressure Duration Induce Changes in Canola Meal Protein for Ruminant Utilisation. Animals (Basel) 2018; 8:ani8090147. [PMID: 30134609 PMCID: PMC6162687 DOI: 10.3390/ani8090147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 08/15/2018] [Accepted: 08/18/2018] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Canola meal, a by-product of oil production from canola seed, is a source of protein commonly incorporated into dairy and feedlot rations. Processing conditions and pressure treatments can alter the quality of protein in canola meal. In this study, the impact of expeller dry heat and moist heat pressure duration time on general nutritional properties, in vitro protein degradability, Maillard reaction product formation, and molecular and microscopic structural characteristics of canola meal were investigated. Increased dry heat temperature rapidly increased digestible protein and non-protein nitrogen content, and constricted amide II secondary structure. Increased moist heat pressure treatment duration promoted browning, and the conversion of protein to more intermediately and slowly degradable forms. Dry heat and moist heat pressure affected meal protein solubility and protein and lipid-related functional groups. Moist heat pressure fragmented canola meal into enzyme-resistant aggregates with crevices containing oil bodies. Induced changes may impact the supply of protein and amino acids and subsequently the yield and composition (protein and lipid) of milk produced by dairy cows. These findings benefit producers of canola meal by further describing the effects of processing and treatment conditions on protein characteristics, particularly those which affect the production potential of ruminants fed canola meal as a source of protein. Abstract To improve the protein nutritional quality of canola (Brassica napus L.) meal, further investigation of the effects of processing conditions and post-production treatments is desirable. The impact of barrel dry heat temperature (20 °C (cold press) and 100 °C (expeller)) and moist heat pressure (MHP) duration time on general nutritional properties, Maillard reaction product (MRP) formation, in vitro protein degradability, and molecular and microscopic structural characteristics of canola meals were investigated. Increased MHP duration reduced (p < 0.05) dry matter, soluble protein, rapidly degradable protein, yellowness (early MRP), whiteness (late MRPs), absorbance at 294 nm (intermediate MRPs), and amide I; and increased (p < 0.05) non-protein N, neutral detergent fibre, neutral detergent insoluble crude protein (CP), intermediately and slowly degradable protein, in vitro effective CP degradability, redness, degree of colour change, and browning. Increased dry heat temperature reduced (p < 0.01) CP and rapidly degradable protein, constricted amide II, reduced (p < 0.05) protein solubility in 0.5% KOH and increased (p < 0.05) acid-detergent fibre and intermediate MRPs. Browning index and redness exhibited potential as rapid indicators of effective CP degradability and soluble protein, respectively. Dry heat and MHP altered (p < 0.05) lipid-related functional groups. Dry heat affected napin solubility, and MHP altered cruciferin and napin solubility. Application of MHP induced the formation of proteolysis-resistant protein aggregates with crevices containing oil bodies. Induced changes may impact the supply of proteins and amino acids and subsequently the yield and composition (protein and lipid) of milk produced by dairy cows.
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Perera SP, McIntosh TC, Wanasundara JPD. Structural Properties of Cruciferin and Napin of Brassica napus (Canola) Show Distinct Responses to Changes in pH and Temperature. PLANTS 2016; 5:plants5030036. [PMID: 27618118 PMCID: PMC5039744 DOI: 10.3390/plants5030036] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 08/22/2016] [Accepted: 08/25/2016] [Indexed: 12/23/2022]
Abstract
The two major storage proteins identified in Brassica napus (canola) were isolated and studied for their molecular composition, structural characteristics and the responses of structural features to the changes in pH and temperature. Cruciferin, a complex of six monomers, has a predominantly β-sheet-containing secondary structure. This protein showed low pH unstable tertiary structure, and distinctly different solubility behaviour with pH when intact in the seed cellular matrix. Cruciferin structure unfolds at pH 3 even at ambient temperature. Temperature-induced structure unfolding was observed above the maximum denaturation temperature of cruciferin. Napin was soluble in a wider pH range than cruciferin and has α-helices dominating secondary structure. Structural features of napin showed less sensitivity to the changes in medium pH and temperature. The surface hydrophobicity (S0) and intrinsic fluorescence of tryptophan residue appear to be good indicators of cruciferin unfolding, however they were not the best to demonstrate structural changes of napin. These two storage proteins of B. napus have distinct molecular characteristics, therefore properties and functionalities they provide are contrasting rather than complementary.
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Affiliation(s)
- Suneru P Perera
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada.
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
| | - Tara C McIntosh
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada.
| | - Janitha P D Wanasundara
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada.
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
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Yadav SKR, Sahu T, Dixit A. Structural and functional characterization of recombinant napin-like protein of Momordica charantia expressed in methylotrophic yeast Pichia pastoris. Appl Microbiol Biotechnol 2016; 100:6703-6713. [PMID: 27020281 DOI: 10.1007/s00253-016-7446-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Revised: 02/22/2016] [Accepted: 03/05/2016] [Indexed: 10/22/2022]
Abstract
Napin and napin-like proteins belong to the 2S albumin seed storage family of proteins and have been shown to display a variety of biological activities. However, due to a high degree of polymorphism, purification of a single napin or napin-like protein exhibiting biological activity is extremely difficult. In the present study, we have produced the napin-like protein of Momordica charantia using the methylotrophic Pichia pastoris expression system. The recombinant napin-like protein (rMcnapin) secreted in the extracellular culture supernatant was enriched by ammonium sulfate precipitation, and purified using size exclusion chromatography at a yield of ∼290 mg/L of culture. Secondary structure analysis of the purified rMcnapin revealed it to be predominantly α-helical with minimal β strand content. CD spectroscopic and fluorescence spectroscopic analyses revealed the rMcnapin to be stable at a wide range of temperatures and pH. The rMcnapin exhibited antifungal activity against Trichoderma viride with an IC50 of ∼3.7 μg/ml and trypsin inhibitor activity with an IC50 of 4.2 μM. Thus, large amounts of homogenous preparations of the biologically active rMcnapin could be obtained at shake flask level, which is otherwise difficult from its natural source.
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Affiliation(s)
- Shailesh Kumar R Yadav
- Gene Regulation Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Tejram Sahu
- Gene Regulation Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Aparna Dixit
- Gene Regulation Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India.
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Wanasundara JPD. Proteins ofBrassicaceaeOilseeds and their Potential as a Plant Protein Source. Crit Rev Food Sci Nutr 2011; 51:635-77. [DOI: 10.1080/10408391003749942] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Pérez SG, Vereijken JM, Koningsveld GA, Gruppen H, Voragen AGJ. Physicochemical Properties of 2S Albumins and the Corresponding Protein Isolate from Sunflower (Helianthus annuus). J Food Sci 2006. [DOI: 10.1111/j.1365-2621.2005.tb09029.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Sadeghi A, Shawrang P. Effects of microwave irradiation on ruminal degradability and in vitro digestibility of canola meal. Anim Feed Sci Technol 2006. [DOI: 10.1016/j.anifeedsci.2005.08.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Schmidt I, Renard D, Rondeau D, Richomme P, Popineau Y, Axelos MAV. Detailed physicochemical characterization of the 2S storage protein from rape (Brassica napus L.). JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2004; 52:5995-6001. [PMID: 15366854 DOI: 10.1021/jf0307954] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Chromatographic, chemical, and spectroscopic techniques were used to characterize the physicochemical properties of napin purified by preparative chromatography. The molar extinction coefficient was determined (epsilon = 0.56), and static and dynamic light scattering measurements enabled the average molecular weight (M(w) = 13919), the second virial coefficient (A(2) = 23.95 x 10(-)(5) mol cm(3) g(-)(2)), and the hydrodynamic radius (R(H) = 1.98 nm) to be determined. No conformational changes were observed by fluorescence and circular dichroism measurements in different buffers at pH 3, 4.6, 7, and 12, confirming the high pH stability of this protein. From MALDI-TOF analysis and after enzymatic digestion, it was found that this purified sample, extracted from the rapeseed variety Express, contained mainly isoform 2SS3_BRANA.
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Affiliation(s)
- Isabelle Schmidt
- Unité de Physico-Chimie des Macromolécules and Unité de Recherches sur les Protéines Végétales et leurs Interactions, INRA, Rue de la Géraudière, 44316 Nantes Cedex 03, France
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THAWORNCHINSOMBUT SUPAWAN, PARK JAEW. ROLE OF pH IN SOLUBILITY AND CONFORMATIONAL CHANGES OF PACIFIC WHITING MUSCLE PROTEINS. J Food Biochem 2004. [DOI: 10.1111/j.1745-4514.2004.tb00061.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Mohamed Salleh MRB, Maruyama N, Adachi M, Hontani N, Saka S, Kato N, Ohkawa Y, Utsumi S. Comparison of protein chemical and physicochemical properties of rapeseed cruciferin with those of soybean glycinin. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2002; 50:7380-5. [PMID: 12452662 DOI: 10.1021/jf0202537] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Rapeseeds contain cruciferin (11S globulin), napin (2S albumin), and oleosin (oil body protein) as major seed proteins. The effects of oil expression and drying conditions on the extraction of these proteins from rapeseed meal were examined. The conditions strongly affected the extraction of oleosin and only weakly affected the extraction of cruciferin and napin. The protein chemical and physicochemical properties of cruciferin, the major protein present, were compared with those of glycinin (soybean 11S globulin) under various conditions. In general, cruciferin exhibited higher surface hydrophobicity, lower thermal stability, and lower and higher solubility at mu= 0.5 and mu = 0.08, respectively, than did glycinin. At the pHs (6.0, 7.6, and 9.0) and ionic strengths (mu= 0.08 and 0.5) examined, the emulsifying ability of cruciferin was worse than that of glycinin, except at mu= 0.08 and pH 7.6. The emulsifying abilities of cruciferin and glycinin did not correlate with thermal stability and surface hydrophobicity. Higher protein concentration, higher heating temperature, higher pH, and lower ionic strength were observed to produce harder gels from cruciferin. Gel hardness partly correlated with the structural stability of cruciferin.
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van Koningsveld GA, Gruppen H, de Jongh HH, Wijngaards G, van Boekel MA, Walstra P, Voragen AG. Effects of pH and heat treatments on the structure and solubility of potato proteins in different preparations. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2001; 49:4889-4897. [PMID: 11600040 DOI: 10.1021/jf010340j] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The soluble potato proteins are mainly composed of patatin and protease inhibitors. Using DSC and both far-UV and near-UV CD spectroscopy, it was shown that potato proteins unfold between 55 and 75 degrees C. Increasing the ionic strength from 15 to 200 mM generally caused an increase in denaturation temperature. It was concluded that either the dimeric protein patatin unfolds in its monomeric state or its monomers are loosely associated and unfold independently. Thermal unfolding of the protease inhibitors was correlated with a decrease in protease inhibitor activities and resulted in an ionic strength dependent loss of protein solubility. Potato proteins were soluble at neutral and strongly acidic pH values. The tertiary structure of patatin was irreversibly altered by precipitation at pH 5. At mildly acidic pH the overall potato protein solubility was dependent on ionic strength and the presence of unfolded patatin.
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