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Gindele MB, Malaszuk KK, Peter C, Gebauer D. On the Binding Mechanisms of Calcium Ions to Polycarboxylates: Effects of Molecular Weight, Side Chain, and Backbone Chemistry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14409-14421. [PMID: 36367750 DOI: 10.1021/acs.langmuir.2c01662] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We experimentally determined the characteristics and Langmuir parameters of the binding of calcium ions to different polycarboxylates. By using potentiometric titrations and isothermal titration calorimetry, the effects of side chain chemistry, pH value, and chain length were systematically investigated using the linear polymers poly(aspartic acid), poly(glutamic acid), and poly(acrylic acid). We demonstrate that for polymers with high polymerization degrees, the binding process is governed by higher-order effects, such as the change of apparent pKa of carboxyl groups, and contributions arising from the whole polymer chain while the chemistry of the monomer unit constituting the polymer plays a subordinate role. In addition, primary binding sites need to be present in the polymer, thus rendering the abundance and sequential arrangement of protonated and deprotonated groups important. The detection of higher-order effects contradicts the assumptions posed by the Langmuir model of noninteracting binding sites and puts a question mark on whether ion binding to polycarboxylates can be described using solely a Langmuir binding model. No single uniform mechanism fits all investigated systems, and the whole polymer chain, including terminal groups, needs to be considered for the interpretation of binding data. Therefore, one needs to be careful when explaining ion binding to polymers solely based on studies on monomers or oligomers.
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Affiliation(s)
- Maxim B Gindele
- Leibniz University Hannover, Institute of Inorganic Chemistry, Callinstr. 9, 30167Hannover, Germany
| | - Krzysztof K Malaszuk
- Leibniz University Hannover, Institute of Inorganic Chemistry, Callinstr. 9, 30167Hannover, Germany
| | - Christine Peter
- Theoretical Chemistry, University of Konstanz, Universitätsstr. 10, 78457Konstanz, Germany
| | - Denis Gebauer
- Leibniz University Hannover, Institute of Inorganic Chemistry, Callinstr. 9, 30167Hannover, Germany
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2
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Liu XC, Liu J, Skibsted LH. Temperature effect on calcium binding to aspartate and glutamate. Food Res Int 2022; 159:111625. [DOI: 10.1016/j.foodres.2022.111625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/30/2022] [Accepted: 07/05/2022] [Indexed: 11/28/2022]
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Akaniro-Ejim NE, Smith PA. Intracellular Ca 2+ in Mouse White Fat Adipocytes: Effects of Extracellular Anions, Growth Hormone, and Their Interaction with Ca 2+ Influx. Bioelectricity 2021. [DOI: 10.1089/bioe.2021.0020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | - Paul A. Smith
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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Jiang Y, Liu XC, Ahrné LM, Skibsted LH. Enthalpy-entropy compensation in calcium binding to acid-base forms of glycine tyrosine dipeptides from hydrolysis of α-lactalbumin. Food Res Int 2021; 149:110714. [PMID: 34600648 DOI: 10.1016/j.foodres.2021.110714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 09/02/2021] [Accepted: 09/10/2021] [Indexed: 11/27/2022]
Abstract
Calcium binding to peptides formed by hydrolysis of whey proteins during digestion is important for calcium uptake in the intestines and affects the antioxidant function of the peptides. For the two dipeptides, Gly-Tyr and Tyr-Gly, potential hydrolysis products of α-lactalbumin, calcium binding to the three forms of each dipeptide in acid-base equilibrium at intestinal pH was determined electrochemically and compared to binding to tyrosine for aqueous 0.16 M NaCl for 5 < pH < 9 at 15 °C, 25 °C, and 37 °C. At milk pH at 25 °C, binding of calcium to the zwitterion of GlyTyr dominates, with an association constant Kass2 = 22 M-1 with ΔH0 = -46 kJ·mol-1, while binding to the mononegative TyrGly dominates for TyrGly with Kass3 = 32 M-1 and ΔH0 = -38 kJ·mol-1. At intestinal conditions, pH = 7 and 37 °C, binding of calcium has similar affinity for GlyTyr and TyrGly, while at higher pH and lower temperature, GlyTyr binds stronger. Density Functional Theory calculations confirmed a stronger binding to the zwitterion of GlyTyr than of TyrGly and an increasing affinity with increasing pH for both. Calcium binding to the acid/base forms of the dipeptides is at neutral pH strongly exothermic with ΔH0 becoming less negative at higher pH, and a linear enthalpy-entropy compensation (r2 = 0.99) results in comparable binding important for calcium bioavailability along the changing distribution among acid-base forms. Calcium binding decreases radical scavenging rate and antioxidative activity of both dipeptides.
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Affiliation(s)
- Yuan Jiang
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark
| | - Xiao-Chen Liu
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark
| | - Lilia M Ahrné
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark
| | - Leif H Skibsted
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark.
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Lai AL, Freed JH. SARS-CoV-2 Fusion Peptide has a Greater Membrane Perturbating Effect than SARS-CoV with Highly Specific Dependence on Ca 2. J Mol Biol 2021; 433:166946. [PMID: 33744314 PMCID: PMC7969826 DOI: 10.1016/j.jmb.2021.166946] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 03/11/2021] [Accepted: 03/11/2021] [Indexed: 11/03/2022]
Abstract
Coronaviruses are a major infectious disease threat, and include the zoonotic-origin human pathogens SARS-CoV-2, SARS-CoV, and MERS-CoV (SARS-2, SARS-1, and MERS). Entry of coronaviruses into host cells is mediated by the spike (S) protein. In our previous ESR studies, the local membrane ordering effect of the fusion peptide (FP) of various viral glycoproteins including the S of SARS-1 and MERS has been consistently observed. We previously determined that the sequence immediately downstream from the S2′ cleavage site is the bona fide SARS-1 FP. In this study, we used sequence alignment to identify the SARS-2 FP, and studied its membrane ordering effect. Although there are only three residue differences, SARS-2 FP induces even greater membrane ordering than SARS-1 FP, possibly due to its greater hydrophobicity. This may be a reason that SARS-2 is better able to infect host cells. In addition, the membrane binding enthalpy for SARS-2 is greater. Both the membrane ordering of SARS-2 and SARS-1 FPs are dependent on Ca2+, but that of SARS-2 shows a greater response to the presence of Ca2+. Both FPs bind two Ca2+ ions as does SARS-1 FP, but the two Ca2+ binding sites of SARS-2 exhibit greater cooperativity. This Ca2+ dependence by the SARS-2 FP is very ion-specific. These results show that Ca2+ is an important regulator that interacts with the SARS-2 FP and thus plays a significant role in SARS-2 viral entry. This could lead to therapeutic solutions that either target the FP-calcium interaction or block the Ca2+ channel.
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Affiliation(s)
- Alex L Lai
- ACERT, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, United States
| | - Jack H Freed
- ACERT, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, United States.
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Jiang Y, Liu XC, de Zawadzki A, Skibsted LH. Binding of calcium to l-serine and o-phospho-l-serine as affected by temperature, pH and ionic strength under milk processing conditions. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2020.104875] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Figueiredo Macedo de Lima J, Aguiar Jordão Mainardi MDC, Puppin-Rontani RM, Pereira Rodrigues-Filho U, Suzy Liporoni PC, Calegaro ML, Rischka K, Baggio Aguiar FH. Bioinspired catechol chemistry for dentin remineralization: A new approach for the treatment of dentin hypersensitivity. Dent Mater 2020; 36:501-511. [DOI: 10.1016/j.dental.2020.01.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 12/20/2019] [Accepted: 01/14/2020] [Indexed: 11/25/2022]
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Gkikas M, Peponis T, Mesar T, Hong C, Avery RK, Roussakis E, Yoo HJ, Parakh A, Patino M, Sahani DV, Watkins MT, Oklu R, Evans CL, Albadawi H, Velmahos G, Olsen BD. Systemically Administered Hemostatic Nanoparticles for Identification and Treatment of Internal Bleeding. ACS Biomater Sci Eng 2019; 5:2563-2576. [PMID: 33405762 DOI: 10.1021/acsbiomaterials.9b00054] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Internal bleeding is an injury that can be difficult to localize and effectively treat without invasive surgeries. Injectable polymeric nanoparticles have been developed that can reduce clotting times and blood loss, but they have yet to incorporate sufficient diagnostic capabilities to assist in identifying bleeding sources. Herein, polymeric nanoparticles were developed to simultaneously treat internal bleeding while incorporating tracers for visualization of the nanoparticles by standard clinical imaging modalities. Addition of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine perchlorate (DiD; a fluorescent dye), biotin functionality, and gold nanoparticles to hemostatic polymeric nanoparticles resulted in nanoparticles amenable to imaging with near-infrared (NIR) imaging, immunohistochemistry, and X-ray computed tomography (CT), respectively. Following a lethal liver resection injury, visualization of accumulated nanoparticles by multiple imaging methods was achieved in rodents, with the highest accumulation observed at the liver injury site, resulting in improved survival rates. Tracer addition to therapeutic nanoparticles allows for an expansion of their applicability, during stabilization by first responders to diagnosis and identification of unknown internal bleeding sites by clinicians using standard clinical imaging modalities.
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Affiliation(s)
- Manos Gkikas
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Chemistry, University of Massachusetts Lowell, Lowell, Massachusetts 01854, United States
| | - Thomas Peponis
- Department of Trauma, Emergency Surgery and Surgical Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02144, United States
| | - Tomaz Mesar
- Department of Trauma, Emergency Surgery and Surgical Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02144, United States
| | - Celestine Hong
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Reginald K Avery
- Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Emmanuel Roussakis
- Wellman Center for Photomedicine, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Hyung-Jin Yoo
- Division of Vascular and Endovascular Surgery, Massachusetts General Hospital, Boston, Massachusetts 02144, United States
| | - Anushri Parakh
- Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02144, United States
| | - Manuel Patino
- Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02144, United States
| | - Dushyant V Sahani
- Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02144, United States
| | - Michael T Watkins
- Division of Vascular and Endovascular Surgery, Massachusetts General Hospital, Boston, Massachusetts 02144, United States
| | - Rahmi Oklu
- Division of Vascular and Interventional Radiology, Mayo Clinic, Scottsdale, Arizona 85259, United States
| | - Conor L Evans
- Wellman Center for Photomedicine, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Hassan Albadawi
- Division of Vascular and Interventional Radiology, Mayo Clinic, Scottsdale, Arizona 85259, United States
| | - George Velmahos
- Department of Trauma, Emergency Surgery and Surgical Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02144, United States
| | - Bradley D Olsen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Gao F, Thornley BS, Tressler CM, Naduthambi D, Zondlo NJ. Phosphorylation-dependent protein design: design of a minimal protein kinase-inducible domain. Org Biomol Chem 2019; 17:3984-3995. [PMID: 30942803 PMCID: PMC6668337 DOI: 10.1039/c9ob00502a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Protein kinases and phosphatases modulate protein structure and function, which in turn regulate cellular activities. The development of novel proteins and protein motifs that are responsive to protein phosphorylation provides new ways to probe the functions of individual protein kinases and the intracellular effects of their activation and downregulation. Herein we develop a minimal motif that is responsive to protein phosphorylation, termed a minimal protein kinase-inducible domain. The encodable protein motif comprises a 7- or 8-residue sequence (DKDADXW or DKDADXXW), derived from EF-Hand calcium-binding domains, that is necessary but not sufficient for binding terbium, combined with a protein phosphorylation site (Ser or Thr at residue 9) that, upon phosphorylation, completes the metal-binding motif. Thus, the motif binds metal poorly and exhibits weak terbium luminescence when not phosphorylated. Upon phosphorylation, the peptide binds metal with significantly higher affinity and exhibits robust terbium luminescence. Phosphorylation results in up to a 23× increase in terbium luminescence. Minimal phosphorylation-dependent motifs as small as 9 residues (DKDADGWIS) were developed. NMR spectroscopy on this lanthanum(iii)·phosphopeptide complex confirmed that binding occurs in a manner similar to that in an EF-Hand, despite the absence of the conserved Glu12 typically present in an EF-Hand. By combining molecular design with known protein kinase recognition sequences, minimal protein kinase-inducible domains were developed that were responsive to phosphorylation by Protein Kinase A (PKA: DKDADRRW(S/pS)IIAK), Protein Kinase C (PKC: DKDADGWI(T/pT)FRRKA), and Casein Kinase 1 (CK1: DKDADDWA(S/pS)I). Phosphorylation by PKA was quantified in HeLa cell extracts, with a 4.4× increase in fluorescence (terbium luminescence) observed at 544 nm. The optimized minimal motif includes alternating aspartate residues at positions 1, 3, and 5, plus binding through the main-chain carbonyl at position 7; a lysine at position 2 to provide electrostatic balance and reduce binding in the absence of phosphorylation; an alanine at residue 4 to promote the αL conformation observed at that position of the EF Hand; a tryptophan at residue 7 or 8 to sensitize terbium luminescence; and a phosphorylation site with serine or threonine at residue 9. Residues at positions 6; 7 or 8; and 10 or later may be changed to provide kinase specificity. In the CK1-responsive peptide, the acidic residues in the proto-terbium-binding motif are employed as part of the kinase recognition sequence. This work thus presents fundamental rules for the design of compact phosphorylation-responsive terbium-binding motifs, with potential further application to motifs responsive to other protein post-translational modifications.
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Affiliation(s)
- Feng Gao
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
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11
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Paik SP, Sen K. Micelle mediated extraction of calcium species in aqueous biphasic systems: A mechanism steered by aggregation number. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.12.065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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12
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Wu J, Cai X, Tang M, Wang S. Novel calcium-chelating peptides from octopus scraps and their corresponding calcium bioavailability. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2019; 99:536-545. [PMID: 29931683 DOI: 10.1002/jsfa.9212] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 06/10/2018] [Accepted: 06/16/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND To reducing the massive marine pollution and resource waste caused by octopus scraps, we developed a novel octopus scraps protein hydrolysate (OSPH), which displays calcium-chelating activity, and we investigated the chelating interaction and calcium bioavailability of OSPH-Ca. RESULTS The structural properties of amido and carboxy groups indicated that they could be the reaction sites for chelation. The particle radius of OSPH increased by 32.25 nm after the calcium chelated with OSPH, indicating intramolecular and intermolecular folding and aggregating. The enthalpy of OSPH increased by 0.8323 after chelation, showing that bands of OSPH-Ca needed more thermal energy to be destroyed than OSPH. Meanwhile, the chelate showed remarkable stability and absorbability under either acidic or basic conditions, which favored calcium absorption in the gastrointestinal tracts of humans. The calcium intake of OSPH-Ca increased by 41% when compared with that of CaCl2 . In particular, OSPH-Ca could protect calcium ions from precipitation caused by dietary inhibitors tannic acid and phytate, while calcium uptake efficiency remained at 3.35 and 1.68 times higher than that of CaCl2 . CONCLUSION These findings revealed the feasibility of transforming octopus scraps into a novel functional calcium chelate based on peptides, promoting environmental sustainability. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Jinhong Wu
- Department of Food Science and Engineering, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Institute of Food and Marine Bioresources, College of Biological Science and Technology, Fuzhou University, Fuzhou, China
| | - Xixi Cai
- Institute of Food and Marine Bioresources, College of Biological Science and Technology, Fuzhou University, Fuzhou, China
| | - Mengru Tang
- Institute of Food and Marine Bioresources, College of Biological Science and Technology, Fuzhou University, Fuzhou, China
| | - Shaoyun Wang
- Institute of Food and Marine Bioresources, College of Biological Science and Technology, Fuzhou University, Fuzhou, China
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Onak G, Şen M, Horzum N, Ercan UK, Yaralı ZB, Garipcan B, Karaman O. Aspartic and Glutamic Acid Templated Peptides Conjugation on Plasma Modified Nanofibers for Osteogenic Differentiation of Human Mesenchymal Stem Cells: A Comparative Study. Sci Rep 2018; 8:17620. [PMID: 30514892 PMCID: PMC6279782 DOI: 10.1038/s41598-018-36109-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 11/14/2018] [Indexed: 11/21/2022] Open
Abstract
Optimization of nanofiber (NF) surface properties is critical to achieve an adequate cellular response. Here, the impact of conjugation of biomimetic aspartic acid (ASP) and glutamic acid (GLU) templated peptides with poly(lactic-co-glycolic acid) (PLGA) electrospun NF on osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs) was evaluated. Cold atmospheric plasma (CAP) was used to functionalize the NF surface and thus to mediate the conjugation. The influence of the CAP treatment following with peptide conjugation to the NF surface was assessed using water contact angle measurements, Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS). The effect of CAP treatment on morphology of NF was also checked using Scanning Electron Microscopy (SEM). Both the hydrophilicity of NF and the number of the carboxyl (-COOH) groups on the surface increased with respect to CAP treatment. Results demonstrated that CAP treatment significantly enhanced peptide conjugation on the surface of NF. Osteogenic differentiation results indicated that conjugating of biomimetic ASP templated peptides sharply increased alkaline phosphatase (ALP) activity, calcium content, and expression of key osteogenic markers of collagen type I (Col-I), osteocalcin (OC), and osteopontin (OP) compared to GLU conjugated (GLU-pNF) and CAP treated NF (pNF). It was further depicted that ASP sequences are the major fragments that influence the mineralization and osteogenic differentiation in non-collagenous proteins of bone extracellular matrix.
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Affiliation(s)
- Günnur Onak
- Department of Biomedical Engineering, İzmir Katip Çelebi University, İzmir, 35620, Turkey
| | - Mustafa Şen
- Department of Biomedical Engineering, İzmir Katip Çelebi University, İzmir, 35620, Turkey
| | - Nesrin Horzum
- Department of Engineering Sciences, İzmir Katip Çelebi University, İzmir, 35620, Turkey
| | - Utku Kürşat Ercan
- Department of Biomedical Engineering, İzmir Katip Çelebi University, İzmir, 35620, Turkey
| | - Ziyşan Buse Yaralı
- Department of Biomedical Engineering, İzmir Katip Çelebi University, İzmir, 35620, Turkey
| | - Bora Garipcan
- Institute of Biomedical Engineering, Bogazici University, 34684, İstanbul, Turkey
| | - Ozan Karaman
- Department of Biomedical Engineering, İzmir Katip Çelebi University, İzmir, 35620, Turkey.
- Bonegraft Biomaterials Co., Ege University Technopolis, 35100, Bornova, İzmir, Turkey.
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Nielsen BS, Alstrom JS, Nicholson BJ, Nielsen MS, MacAulay N. Permeant-specific gating of connexin 30 hemichannels. J Biol Chem 2017; 292:19999-20009. [PMID: 28982982 DOI: 10.1074/jbc.m117.805986] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 09/28/2017] [Indexed: 11/06/2022] Open
Abstract
Gap junctions confer interconnectivity of the cytoplasm in neighboring cells via docking of two connexons expressed in each of the adjacent membranes. Undocked connexons, referred to as hemichannels, may open and connect the cytoplasm with the extracellular fluid. The hemichannel configuration of connexins (Cxs) displays isoform-specific permeability profiles that are not directly determined by the size and charge of the permeant. To further explore Ca2+-mediated gating and permeability features of connexin hemichannels, we heterologously expressed Cx30 hemichannels in Xenopus laevis oocytes. The sensitivity toward divalent cation-mediated gating differed between small atomic ions (current) and fluorescent dye permeants, indicating that these permeants are distinctly gated. Three aspartate residues in Cx30 (Asp-50, Asp-172, and Asp-179) have been implicated previously in the Ca2+ sensitivity of other hemichannel isoforms. Although the aspartate at position Asp-50 was indispensable for divalent cation-dependent gating of Cx30 hemichannels, substitutions of the two other residues had no significant effect on gating, illustrating differences in the gating mechanisms between connexin isoforms. Using the substituted cysteine accessibility method (SCAM), we evaluated the role of possible pore-lining residues in the permeation of ions and ethidium through Cx30 hemichannels. Of the cysteine-substituted residues, interaction of a proposed pore-lining cysteine at position 37 with the positively charged compound [2-(trimethylammonium)ethyl] methane thiosulfonate bromide (MTS-ET) increased Cx30-mediated currents with unperturbed ethidium permeability. In summary, our results demonstrate that the permeability of hemichannels is regulated in a permeant-specific manner and underscores that hemichannels are selective rather than non-discriminating and freely diffusable pores.
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Affiliation(s)
| | | | - Bruce J Nicholson
- Department of Biochemistry, School of Medicine, University of Texas Health Science Center, San Antonio, Texas 78229
| | - Morten Schak Nielsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
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Zinc bioavailability from whey. Enthalpy-entropy compensation in protein binding. Food Res Int 2016; 89:749-755. [DOI: 10.1016/j.foodres.2016.10.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 09/29/2016] [Accepted: 10/02/2016] [Indexed: 01/05/2023]
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Hammouda AN, Jackson GE, Bonomo RP, Elmagbari FM. Formation and spectral properties of metal ion complexes of tripeptides. Inorganica Chim Acta 2016. [DOI: 10.1016/j.ica.2016.07.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Mineral nutrient interaction: Improving bioavailability of calcium and iron. Food Sci Biotechnol 2016; 25:1233-1241. [PMID: 30263400 DOI: 10.1007/s10068-016-0196-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 06/16/2016] [Accepted: 06/19/2016] [Indexed: 12/15/2022] Open
Abstract
Insufficient uptake of essential metals leads to serious malnutrition, which is a worldwide problem. Low bioavailability of iron and calcium may lead to anemia and osteoporosis, respectively, even in individuals with a high dietary intake. For iron, fractionation of meat proteins was studied in order to increase iron bioavailability from other meal components, and uptake of iron was found to increase with minimal risk of increasing oxidative damage. Calcium binding to peptides was found to prevent formation of insoluble calcium salts otherwise hampering absorption particularly in combination with calcium hydroxycarboxylates, entailing spontaneous supersaturation. Based on a review of results from different strategies available for increasing bioavailability, safe iron fortification is suggested to be supported by calcium, with modulation of iron as a prooxidant.
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Baakdah MM, Tsopmo A. Identification of peptides, metal binding and lipid peroxidation activities of HPLC fractions of hydrolyzed oat bran proteins. Journal of Food Science and Technology 2016; 53:3593-3601. [PMID: 27777466 DOI: 10.1007/s13197-016-2341-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 08/31/2016] [Accepted: 09/08/2016] [Indexed: 11/25/2022]
Abstract
The aim of this study was to evaluate metal binding and antioxidant activities of hydrolyzed oat bran proteins followed by the determination of peptide sequences. Protamex oat bran protein hydrolysates (OBPH) were separated by reverse-phase HPLC into eight peptide fractions (F1-F8) and their abilities to either chelate metals (Fe2+, Ca2+) or prevent the oxidation of lipids were investigated. In the Fe2+ chelation assay, OBPH had significantly (p < 0.05) higher activity (39.7 %) than the best performed fraction F7 (22.8 %). The second most active was F5 with 12.1 % chelating activity and this was higher than the activity of the tripeptide glutathione (5.8 %) used as control. The two most Fe2+ chelating fractions (F5, F7) however had weak calcium binding (0.6-1.0 %) properties at peptide concentration ranging from 0.2 to 1.0 mg/mL. In the lipid peroxidation assay, OBPH and all HPLC fractions prevented the oxidation of linoleic acid. More than 60 peptides mainly derived from globulin and avenin proteins were identified using tandem mass spectrometry.
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Affiliation(s)
- Morooj M Baakdah
- Food Science and Nutrition Program, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6 Canada
| | - Apollinaire Tsopmo
- Food Science and Nutrition Program, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6 Canada ; Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6 Canada
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Tang N, Skibsted LH. Calcium Binding to Amino Acids and Small Glycine Peptides in Aqueous Solution: Toward Peptide Design for Better Calcium Bioavailability. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:4376-4389. [PMID: 27159329 DOI: 10.1021/acs.jafc.6b01534] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Deprotonation of amino acids as occurs during transfer from stomach to intestines during food digestion was found by comparison of complex formation constants as determined electrochemically for increasing pH to increase calcium binding (i) by a factor of around 6 for the neutral amino acids, (ii) by a factor of around 4 for anions of the acidic amino acids aspartic and glutamic acid, and (iii) by a factor of around 5.5 for basic amino acids. Optimized structures of the 1:1 complexes and ΔHbinding for calcium binding as calculated by density functional theory (DFT) confirmed in all complexes a stronger calcium binding and shorter calcium-oxygen bond length in the deprotonated form. In addition, the stronger calcium binding was also accompanied by a binding site shift from carboxylate binding to chelation by α-amino group and carboxylate oxygen for leucine, aspartate, glutamate, alanine, and asparagine. For binary amino acid mixtures, the calcium-binding constant was close to the predicted geometric mean of the individual amino acid binding constants indicating separate binding of calcium to two amino acids when present together in solution. At high pH, corresponding to conditions for calcium absorption, the binding affinity increased in the order Lys < Arg < Cys < Gln < Gly ∼ Ala < Asn < His < Leu < Glu< Asp. In a series of glycine peptides, calcium-binding affinity was found to increase in the order Gly-Leu ∼ Gly-Gly < Ala-Gly < Gly-His ∼ Gly-Lys-Gly < Glu-Cys-Gly < Gly-Glu, an ordering confirmed by DFT calculations for the dipeptides and which also accounted for large synergistic effects in calcium binding for up to 6 kJ/mol when compared to the corresponding amino acid mixtures.
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Affiliation(s)
- Ning Tang
- Food Chemistry, Department of Food Science, University of Copenhagen , Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
| | - Leif H Skibsted
- Food Chemistry, Department of Food Science, University of Copenhagen , Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
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Garcia AC, Vavrusova M, Skibsted LH. Calcium d-Saccharate: Aqueous Solubility, Complex Formation, and Stabilization of Supersaturation. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:2352-2360. [PMID: 26934422 DOI: 10.1021/acs.jafc.6b00166] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc° = −34 ± 6 kJ mol–1, and ΔSassoc° = −55 ± 9 J mol–1 K–1, were determined electrochemically. Calcium d-saccharate is sparingly soluble, with a solubility product, Ksp, of (6.17 ± 0.32) × 10–7 at 25 °C, only moderately increasing with the temperature: ΔHsol° = 48 ± 2 kJ mol–1, and ΔSassoc° = 42 ± 7 J mol–1 K–1. Equilibria in supersaturated solutions of calcium d-saccharate seem only to adjust slowly, as seen from calcium activity measurements in calcium d-saccharate solutions made supersaturated by cooling. Solutions formed by isothermal dissolution of calcium d-gluconate in aqueous potassium d-saccharate becomes spontaneously supersaturated with both d-gluconate and d-saccharate calcium salts, from which only calcium d-saccharate slowly precipitates. Calcium d-saccharate is suggested to act as a stabilizer of supersaturated solutions of other calcium hydroxycarboxylates with endothermic complex formation through a heat-induced shift in calcium complex distribution with slow equilibration upon cooling.
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Affiliation(s)
- André C Garcia
- Food Chemistry, Department of Food Science, University of Copenhagen , Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
- Insituto Federal de Educação, Ciência e Tecnologia de São Paulo , Campus Capivari, Avenida Doutor Ênio Pires de Camargo, 2971, São João Batista, Capivari, São Paulo 13360-000, Brazil
| | - Martina Vavrusova
- Food Chemistry, Department of Food Science, University of Copenhagen , Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
| | - Leif H Skibsted
- Food Chemistry, Department of Food Science, University of Copenhagen , Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
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Skibsted LH. Mineral nutrient interaction: Improving bioavailability of calcium and iron. Food Sci Biotechnol 2016. [PMID: 30263400 DOI: 10.1007/s10068-016-0196-192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023] Open
Abstract
Insufficient uptake of essential metals leads to serious malnutrition, which is a worldwide problem. Low bioavailability of iron and calcium may lead to anemia and osteoporosis, respectively, even in individuals with a high dietary intake. For iron, fractionation of meat proteins was studied in order to increase iron bioavailability from other meal components, and uptake of iron was found to increase with minimal risk of increasing oxidative damage. Calcium binding to peptides was found to prevent formation of insoluble calcium salts otherwise hampering absorption particularly in combination with calcium hydroxycarboxylates, entailing spontaneous supersaturation. Based on a review of results from different strategies available for increasing bioavailability, safe iron fortification is suggested to be supported by calcium, with modulation of iron as a prooxidant.
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Affiliation(s)
- Leif Horsfelt Skibsted
- Department of Food Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
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Lin J, Cai X, Tang M, Wang S. Preparation and Evaluation of the Chelating Nanocomposite Fabricated with Marine Algae Schizochytrium sp. Protein Hydrolysate and Calcium. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:9704-14. [PMID: 26499390 DOI: 10.1021/acs.jafc.5b04001] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Marine algae have been becoming a popular research topic because of their biological implication. The algae peptide-based metal-chelating complex was investigated in this study. Schizochytrium sp. protein hydrolysate (SPH) possessing high Ca-binding capacity was prepared through stepwise enzymatic hydrolysis to a degree of hydrolysis of 22.46%. The nanocomposites of SPH chelated with calcium ions were fabricated in aqueous solution at pH 6 and 30 °C for 20 min, with the ratio of SPH to calcium 3:1 (w/w). The size distribution showed that the nanocomposite had compact structure with a radius of 68.16 ± 0.50 nm. SPH was rich in acidic amino acids, accounting for 33.55%, which are liable to bind with calcium ions. The molecular mass distribution demonstrated that the molecular mass of SPH was principally concentrated at 180-2000 Da. UV scanning spectroscopy and Fourier transform infrared spectroscopy suggested that the primary sites of calcium-binding corresponded to the carboxyl groups, carbonyl groups, and amino groups of SPH. The results of fluorescent spectroscopy, size distribution, atomic force microscope, and (1)H nuclear magnetic resonance spectroscopy suggested that calcium ions chelated with SPH would cause intramolecular and intermolecular folding and aggregating. The SPH-calcium chelate exerted remarkable stability and absorbability under either acidic or basic conditions, which was in favor of calcium absorption in the gastrointestinal tracts of humans. The investigation suggests that SPH-calcium chelate has the potential prospect to be utilized as a nutraceutical supplement to improve bone health in the human body.
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Affiliation(s)
- Jiaping Lin
- College of Biological Science and Technology, Fuzhou University , Fuzhou, Fujian 350108, People's Republic of China
| | - Xixi Cai
- College of Biological Science and Technology, Fuzhou University , Fuzhou, Fujian 350108, People's Republic of China
- College of Chemistry, Fuzhou University , Fuzhou, Fujian 350108, People's Republic of China
| | - Mengru Tang
- College of Biological Science and Technology, Fuzhou University , Fuzhou, Fujian 350108, People's Republic of China
| | - Shaoyun Wang
- College of Biological Science and Technology, Fuzhou University , Fuzhou, Fujian 350108, People's Republic of China
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Vavrusova M, Liang R, Skibsted LH. Thermodynamics of dissolution of calcium hydroxycarboxylates in water. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:5675-81. [PMID: 24869479 DOI: 10.1021/jf501453c] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Aqueous solubility of calcium l-lactate, calcium d-gluconate, and calcium d-lactobionate increases with temperature (10-30 °C investigated), most significantly for the least soluble d-gluconate, while the calcium ion activity of the saturated solutions decreases with temperature, as measured electrochemically, most significantly for the most soluble d-lactobionate. This unusual behavior is discussed in relation to dairy processing and explained by endothermic binding of calcium to hydroxycarboxylate anions determined to have ΔH°ass = (31 ± 3) kJ·mol(-1) for l-lactate, (34 ± 2) kJ·mol(-1) for d-gluconate, and (29 ± 3) kJ·mol(-1) for d-lactobionate in 1:1 complexes with thermodynamic binding constants at 25 °C of Kass = 49 (l-lactate), 88 (d-gluconate), and 140 (d-lactobionate). Quantum mechanical calculations within density functional theory (DFT) confirm the ordering of strength of binding. The complex formation is entropy driven with ΔS°ass > 0, resulting in decreasing calcium ion activity in aqueous solutions for increasing temperature, even for the saturated solutions despite increasing solubility.
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Affiliation(s)
- Martina Vavrusova
- Food Chemistry, Department of Food Science, University of Copenhagen , Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
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Vavrusova M, Munk MB, Skibsted LH. Aqueous solubility of calcium L-lactate, calcium D-gluconate, and calcium D-lactobionate: importance of complex formation for solubility increase by hydroxycarboxylate mixtures. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:8207-14. [PMID: 23906043 DOI: 10.1021/jf402124n] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Among the calcium hydroxycarboxylates important for cheese quality, D-lactobionate [Ksp = (7.0 ± 0.3) × 10(-3) mol(3) L(-3)] and L-lactate [Ksp = (5.8 ± 0.2) × 10(-3) mol(3) L(-3)] were found more soluble than D-gluconate [Ksp = (7.1 ± 0.2) × 10(-4) mol(3) L(-3)], as indicated by the solubility products determined electrochemically for aqueous 1.0 M NaCl at 25.0 °C. Still, solubility of calcium L-lactate increases by 45% in the presence of 0.50 M sodium D-gluconate and by 37% in the presence of 0.50 M sodium D-lactobionate, while solubility of calcium D-gluconate increases by 66 and 85% in the presence of 0.50 M sodium L-lactate and 0.50 M sodium D-lactobionate, respectively, as determined by complexometric titration. Sodium L-lactate and sodium D-gluconate have only little influence on solubility of calcium D-lactobionate. The increased solubility is described quantitatively by calcium binding to D-gluconate (K1 = 14 ± 3 mol(-1) L) in 1.0 M NaCl at 25 °C, D-lactobionate (K1 = 11 ± 2 mol(-1) L), and L-lactate (K1 = 8 ± 2 mol(-1) L), as indicated by the association constants determined electrochemically. In mixed hydroxycarboxylate solutions, calcium binding is quantitatively described by the geometric mean of the individual association constants for both aqueous 1.0 and 0.20 M NaCl, indicating a 1:1 stoichiometry for complex formation.
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Affiliation(s)
- Martina Vavrusova
- Food Chemistry, Department of Food Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
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