Nuclear magnetic resonance

@misc{s20bff54682407e912d3d4c589698377d6e9a10b9d,
    author = "Bachovchin, W. and Roberts, D.",
    title = "A Study by Nitrogen-is Nuclear Magnetic Resonance Spectroscop'f of the State of Histidine in the Catalytic Triad of A-lytic Protease 1",
    url = "https://www.semanticscholar.org/paper/0bff54682407e912d3d4c589698377d6e9a10b9d",
    is_oa = "true",
    semanticscholar_id = "0bff54682407e912d3d4c589698377d6e9a10b9d"
}

@article{deber1970nuclear,
    author = "Deber, C. M. and Bovey, F. A. and Carver, J. P. and Blout, Elkan R.",
    title = "Nuclear magnetic resonance evidence for cis-peptide bonds in proline oligomers",
    year = "1970",
    journal = "Journal of the American Chemical Society",
    url = "https://doi.org/10.1021/ja00724a016",
    doi = "10.1021/ja00724a016",
    number = "21",
    pages = "6191-6198",
    volume = "92"
}

@article{s27bc3558b72194b0afad8e2377358397c4d9c01b3,
    author = "Bachovchin, W. and Roberts, John D.",
    title = "A Study by Nitrogen-15 Nuclear Magnetic Resonance Spectroscopy of the State of Histidine in the Catalytic Triad of α-Lytic Protease",
    year = "1978",
    url = "https://www.semanticscholar.org/paper/7bc3558b72194b0afad8e2377358397c4d9c01b3",
    is_oa = "true",
    semanticscholar_citation_count = "1",
    semanticscholar_id = "7bc3558b72194b0afad8e2377358397c4d9c01b3"
}

@misc{pivcova1981nmr1,
    author = "Pivcova, H. and Saudek, V. and Drobnik, J. and Vlasak, J",
    title = "NMR study of poly (aspartic acid) I. - and -peptide bonds in poly (aspartic acid) prepared by thermal polycondensation",
    year = "1981",
    howpublished = "Biopolymers, v. 20, p. 1605-1614",
    note = "talkorigins\_source = {true}; raw\_reference = {Pivcova, H., Saudek, V., Drobnik, J., and Vlasak, J., 1981, NMR study of poly (aspartic acid) I. - and -peptide bonds in poly (aspartic acid) prepared by thermal polycondensation: Biopolymers, v. 20, p. 1605-1614.}"
}

The structure of poly(aspartic acid) prepared by thermal polycondensation has been studied by means of nmr spectroscopy. The analysis of the 13 C‐nmr spectra of the polymer at various pH values and comparison with the spectrum of poly(α‐ L ‐aspartic acid) revealed that the polymer contained aspartic acid linked in α‐ and β‐peptide bonds. The mole fraction of the β‐peptide bonds has been found to be 0.8 ± 0.1. The significance of the results for the evolutionary theory of S. W. Fox is mentioned.

@article{pivcová1981nmr,
    author = "Pivcová, H. and Saudek, V. and Drobník, J. and Vlasák, J.",
    title = "Nmr study of poly(aspartic acid). I. α‐ and β‐Peptide bonds in poly(aspartic acid) prepared by thermal polycondensation",
    year = "1981",
    journal = "Biopolymers",
    abstract = "The structure of poly(aspartic acid) prepared by thermal polycondensation has been studied by means of nmr spectroscopy. The analysis of the 13 C‐nmr spectra of the polymer at various pH values and comparison with the spectrum of poly(α‐ L ‐aspartic acid) revealed that the polymer contained aspartic acid linked in α‐ and β‐peptide bonds. The mole fraction of the β‐peptide bonds has been found to be 0.8 ± 0.1. The significance of the results for the evolutionary theory of S. W. Fox is mentioned.",
    url = "https://doi.org/10.1002/bip.1981.360200804",
    doi = "10.1002/bip.1981.360200804",
    number = "8",
    pages = "1605-1614",
    volume = "20"
}

@article{saudek1981estimation,
    author = "Saudek, V. and Drobnik, J.",
    title = "Estimation of? and? peptide bonds in thermal poly(aspartic acid) by potentiometric titration",
    year = "1981",
    journal = "Polymer Bulletin",
    url = "https://doi.org/10.1007/bf00255703",
    doi = "10.1007/bf00255703",
    number = "8",
    volume = "4"
}

The nature of peptide bonds in poly(aspartic acid) prepared by debenzylation of poly(β‐benzyl‐ L ‐aspartate) under various conditions has been studied by means of nmr spectroscopy. It was established that the majority of the polymers prepared, as well as the commercially obtained polymer, contained aspartic acid linked in both α‐ and β‐peptide bonds. The purest polymer, having practically undetectable amounts of β‐bond, was prepared by debenzylation by HBr in trifluoroacetic acid. It was established that the β‐bonds are formed via succinimides.

@article{saudek1981nmr,
    author = "Saudek, V. and Pivcová, H. and Drobník, J.",
    title = "Nmr study of poly(aspartic acid). II. α‐ and β‐Peptide bonds in poly(aspartic acid) prepared by common methods",
    year = "1981",
    journal = "Biopolymers",
    abstract = "The nature of peptide bonds in poly(aspartic acid) prepared by debenzylation of poly(β‐benzyl‐ L ‐aspartate) under various conditions has been studied by means of nmr spectroscopy. It was established that the majority of the polymers prepared, as well as the commercially obtained polymer, contained aspartic acid linked in both α‐ and β‐peptide bonds. The purest polymer, having practically undetectable amounts of β‐bond, was prepared by debenzylation by HBr in trifluoroacetic acid. It was established that the β‐bonds are formed via succinimides.",
    url = "https://doi.org/10.1002/bip.1981.360200805",
    doi = "10.1002/bip.1981.360200805",
    number = "8",
    pages = "1615-1623",
    volume = "20"
}

Polypeptides of dicarboxylic amino acids having the monomer units linked in α‐ and ω‐peptide bonds contain two kinds of carboxyls of different acidity. How well potentiometric titration can distinguish these two carboxyls and so characterize the nature of the peptide bonds is evaluated critically. An analysis of the equation describing the dependence of pH on the degree of neutralization based on neglecting the polymer effect and a discussion of the dissociation behavior of polyanions show that the method of evaluating experimental data found in the literature is incorrect. Nevertheless, if a conformational transition does not interfere, some useful and reliable information may be gained by this method; namely, an indication of the presence of two different peptide bonds, their mole ratio, and an approximate p K value for the carboxyl of the amino acid linked in the ω‐peptide bond. The presence of two types of carboxyls complicates the evaluation of the titration curves in the conformation studies.

@article{saudek1981use,
    author = "Saudek, V.",
    title = "Use of potentiometric titration for determination of α‐ and ω‐peptide bonds in poly(aspartic acid) and poly(glutamic acid)",
    year = "1981",
    journal = "Biopolymers",
    abstract = "Polypeptides of dicarboxylic amino acids having the monomer units linked in α‐ and ω‐peptide bonds contain two kinds of carboxyls of different acidity. How well potentiometric titration can distinguish these two carboxyls and so characterize the nature of the peptide bonds is evaluated critically. An analysis of the equation describing the dependence of pH on the degree of neutralization based on neglecting the polymer effect and a discussion of the dissociation behavior of polyanions show that the method of evaluating experimental data found in the literature is incorrect. Nevertheless, if a conformational transition does not interfere, some useful and reliable information may be gained by this method; namely, an indication of the presence of two different peptide bonds, their mole ratio, and an approximate p K value for the carboxyl of the amino acid linked in the ω‐peptide bond. The presence of two types of carboxyls complicates the evaluation of the titration curves in the conformation studies.",
    url = "https://doi.org/10.1002/bip.1981.360200806",
    doi = "10.1002/bip.1981.360200806",
    number = "8",
    pages = "1625-1633",
    volume = "20"
}

@article{wolk1994one,
    author = "Wolk, Steven K. and Swift, Graham and Paik, Yi Hyon and Yocom, Kathryn M. and Smith, Rebecca L. and Simon, Ethan S.",
    title = "One- and Two-Dimensional Nuclear Magnetic Resonance Characterization of Poly(aspartic acid) Prepared by Thermal Polymerization of L-Aspartic Acid",
    year = "1994",
    journal = "Macromolecules",
    url = "https://doi.org/10.1021/ma00104a016",
    doi = "10.1021/ma00104a016",
    number = "26",
    pages = "7613-7620",
    volume = "27"
}

@article{doi101016s0032386100001178,
    author = "Jo, S. and Engel, P. and Mikos, A.",
    title = "Synthesis of poly(ethylene glycol)-tethered poly(propylene fumarate) and its modification with GRGD peptide",
    year = "2000",
    journal = "Polymer",
    url = "https://www.semanticscholar.org/paper/5b7c8c1c74a9e27fcb5ca24a295a6e728dc71b6f",
    doi = "10.1016/S0032-3861(00)00117-8",
    is_oa = "true",
    number = "21",
    pages = "7595-7604",
    semanticscholar_citation_count = "83",
    semanticscholar_id = "5b7c8c1c74a9e27fcb5ca24a295a6e728dc71b6f",
    volume = "41"
}

@article{nakato2000synthesis,
    author = "Nakato, Takeshi and Kusuno, Atsushi and Kakuchi, Toyoji",
    title = "Synthesis of poly(succinimide) by bulk polycondensation ofL-aspartic acid with an acid catalyst",
    year = "2000",
    journal = "Journal of Polymer Science Part A: Polymer Chemistry",
    url = "https://doi.org/10.1002/(sici)1099-0518(20000101)38:1<117::aid-pola15>3.0.co;2-f",
    doi = "10.1002/(sici)1099-0518(20000101)38:1<117::aid-pola15>3.0.co;2-f",
    number = "1",
    pages = "117-122",
    volume = "38"
}

@article{jiang2001synthesis,
    author = "Jiang, H. L. and Tang, G. P. and Zhu, K. J.",
    title = "Synthesis of Biodegradable Amphoteric Poly[(aspartic acid)-co-lysine] by Thermal Polycondensation",
    year = "2001",
    journal = "Macromolecular Bioscience",
    url = "https://doi.org/10.1002/1616-5195(20010801)1:6<266::aid-mabi266>3.0.co;2-k",
    doi = "10.1002/1616-5195(20010801)1:6<266::aid-mabi266>3.0.co;2-k",
    number = "6",
    pages = "266-269",
    volume = "1"
}

@article{tomida2001polyaspartic,
    author = "TOMIDA, Masayuki and NAKATO, Takeshi",
    title = "Poly(aspartic acid)",
    year = "2001",
    journal = "Kobunshi",
    url = "https://doi.org/10.1295/kobunshi.50.393",
    doi = "10.1295/kobunshi.50.393",
    number = "6",
    pages = "393-393",
    volume = "50"
}

@article{doi101021bm0255950,
    author = "Wang, Dong-an and Ji, J. and Sun, Yong-hong and Shen, Jia-cong and Feng, Lin-Xian and Elisseeff, J.",
    title = "In situ immobilization of proteins and RGD peptide on polyurethane surfaces via poly(ethylene oxide) coupling polymers for human endothelial cell growth.",
    year = "2002",
    journal = "Biomacromolecules",
    url = "https://www.semanticscholar.org/paper/5ad5e838fb780b2663d97962734e75faca782dc1",
    doi = "10.1021/BM0255950",
    is_oa = "true",
    number = "6",
    pages = "1286-1295",
    semanticscholar_citation_count = "78",
    semanticscholar_id = "5ad5e838fb780b2663d97962734e75faca782dc1",
    volume = "3"
}

@article{doi101021bc060014f,
    author = "Lee, Ha Young and Jee, Hyeok and Seo, Sung-Mi and Kwak, Byung-Kook and Khang, G. and Cho, S.",
    title = "Diethylenetriaminepentaacetic acid-gadolinium (DTPA-Gd)-conjugated polysuccinimide derivatives as magnetic resonance imaging contrast agents.",
    year = "2006",
    journal = "Bioconjugate chemistry",
    url = "https://www.semanticscholar.org/paper/220686fc8f7243813d25f287e1dbc14db0e9dbd4",
    doi = "10.1021/BC060014F",
    is_oa = "true",
    number = "3",
    pages = "700-706",
    semanticscholar_citation_count = "39",
    semanticscholar_id = "220686fc8f7243813d25f287e1dbc14db0e9dbd4",
    volume = "17"
}

@article{s2fef402f1ac495238a940966dae79865d03237b86,
    author = "Xiao, Qi",
    title = "Preparation,Characterization and Preliminary Trichomonacidal Effect of Poly Aspartic Acid-metronidazole Nanoprodrug",
    year = "2009",
    journal = "Progress in Biochemistry and Biophysics",
    url = "https://www.semanticscholar.org/paper/fef402f1ac495238a940966dae79865d03237b86",
    doi = "10.3724/sp.j.1206.2008.00863",
    is_oa = "true",
    number = "8",
    pages = "1056-1063",
    semanticscholar_id = "fef402f1ac495238a940966dae79865d03237b86",
    volume = "36"
}

@article{doi1014314polimery2010562,
    author = "Tudorachi, N. and Lipsa, R.",
    title = "Synthesis and characterization of poly(vinyl alcohol-co-aspartic acid) copolymers",
    year = "2010",
    journal = "Polimery",
    url = "http://en.www.ichp.pl/attach.php?id=592",
    doi = "10.14314/POLIMERY.2010.562",
    is_oa = "true",
    number = "07/08",
    pages = "562-567",
    semanticscholar_citation_count = "12",
    semanticscholar_id = "537897557e4239b1d5973a7a8d37ccd33433a6ae",
    volume = "55"
}

A novel poly[([Formula: see text]-CL)-co-(GA-alt-L-Asp)] with improved hydrophilicity was prepared. The monomer 3(S)-[(benzyloxycarbony)methyl]-1,4-dioxane-2,5-dione (BMD) was prepared from aspartic acid. The polymer was obtained by ring-opening polymerization of [Formula: see text]-caprolactone ([Formula: see text]-CL) and BMD. Poly[([Formula: see text]-CL)-co-(GA-alt-L-Asp)] was synthesized by deprotection. The structure and properties of the polymer were characterized using 1 H nuclear magnetic resonance, gel permeation chromatography, and differential scanning calorimetry. The melting point and melting enthalpy of the polymer decreased with the increase of BMD. The structural regularity of polycaprolactone was destroyed by the BMD. A laminin-derived peptide [i.e., Arg-Gly-Asp (RGD)] was covalently tethered to the carboxyl groups and the peptide-grafted films. Results indicated that the addition of RGD had beneficial effects for cell growth, as shown by scanning electron microscopy.

@article{doi104015s1016237215500532,
    author = "Na, Qian and Xie, F. and Liang, Hao and Li, Xianfeng and Tang, Shuo and Zhu, Jixiang",
    title = "SYNTHESIS OF POLY[(ε-CL)-co-(GA-alt-L-Asp)] COPOLYMER AND EFFECTS ON CELLS AFTER COUPLING WITH SMALL PEPTIDE",
    year = "2015",
    journal = "Biomedical Engineering: Applications, Basis and Communications",
    abstract = "A novel poly[([Formula: see text]-CL)-co-(GA-alt-L-Asp)] with improved hydrophilicity was prepared. The monomer 3(S)-[(benzyloxycarbony)methyl]-1,4-dioxane-2,5-dione (BMD) was prepared from aspartic acid. The polymer was obtained by ring-opening polymerization of [Formula: see text]-caprolactone ([Formula: see text]-CL) and BMD. Poly[([Formula: see text]-CL)-co-(GA-alt-L-Asp)] was synthesized by deprotection. The structure and properties of the polymer were characterized using 1 H nuclear magnetic resonance, gel permeation chromatography, and differential scanning calorimetry. The melting point and melting enthalpy of the polymer decreased with the increase of BMD. The structural regularity of polycaprolactone was destroyed by the BMD. A laminin-derived peptide [i.e., Arg-Gly-Asp (RGD)] was covalently tethered to the carboxyl groups and the peptide-grafted films. Results indicated that the addition of RGD had beneficial effects for cell growth, as shown by scanning electron microscopy.",
    url = "https://www.semanticscholar.org/paper/0162e883af5795a5b4a28fb4b268c699107738df",
    doi = "10.4015/S1016237215500532",
    is_oa = "true",
    number = "06",
    pages = "1550053",
    semanticscholar_id = "0162e883af5795a5b4a28fb4b268c699107738df",
    volume = "27"
}

New sequences of nanocomposites including numerous maleic acid-grafted poly(butylene adipate-co-terephthalate) (g-PBAT) and cellulose nanocrystals (CNC) were efficaciously fabricated via transesterification and polycondensation processes with the covalent bonds between the polymer and reinforcing fillers. The grafting interaction of maleic acid onto PBAT was successfully demonstrated using Fourier transform infrared (FTIR) and 13C-nuclear magnetic resonance (NMR) spectra. The morphology of g-PBAT/CNC nanocomposites was investigated by wide-angle X-ray diffraction and transmission electron microscopy. Both results indicate that the CNC was randomly dispersed into the g-PBAT polymer matrix. The storage modulus at −80 and 25 °C was significantly enhanced with the incorporation of CNC into g-PBAT matrix. The crystallization rate of g-PBAT/CNC nanocomposites increased as the loading of CNC increased. With the incorporation of 3 wt% CNC, the half-time for crystallization of the g-PBAT/CNC composite decreased about 50~80% as compared with the same isothermal crystallization of pure polymer matrix. All water vapor permeation (WVP) values of all g-PBAT/CNC nanocomposites decreased as the loading of CNC increased. The decrease in WVP may be attributed to the addition of stiff CNC, causing the increase on the permeation route in the water molecules in the g-PBAT polymer matrix.

@article{doi103390polym14132742,
    author = "Hung, Yu-Jia and Chiang, Ming-Yen and Wang, Enhui and Wu, Tzong‐Ming",
    title = "Synthesis, Characterization, and Physical Properties of Maleic Acid-Grafted Poly(butylene adipate-co-terephthalate)/Cellulose Nanocrystal Composites",
    year = "2022",
    journal = "Polymers",
    abstract = "New sequences of nanocomposites including numerous maleic acid-grafted poly(butylene adipate-co-terephthalate) (g-PBAT) and cellulose nanocrystals (CNC) were efficaciously fabricated via transesterification and polycondensation processes with the covalent bonds between the polymer and reinforcing fillers. The grafting interaction of maleic acid onto PBAT was successfully demonstrated using Fourier transform infrared (FTIR) and 13C-nuclear magnetic resonance (NMR) spectra. The morphology of g-PBAT/CNC nanocomposites was investigated by wide-angle X-ray diffraction and transmission electron microscopy. Both results indicate that the CNC was randomly dispersed into the g-PBAT polymer matrix. The storage modulus at −80 and 25 °C was significantly enhanced with the incorporation of CNC into g-PBAT matrix. The crystallization rate of g-PBAT/CNC nanocomposites increased as the loading of CNC increased. With the incorporation of 3 wt\% CNC, the half-time for crystallization of the g-PBAT/CNC composite decreased about 50\textasciitilde 80\% as compared with the same isothermal crystallization of pure polymer matrix. All water vapor permeation (WVP) values of all g-PBAT/CNC nanocomposites decreased as the loading of CNC increased. The decrease in WVP may be attributed to the addition of stiff CNC, causing the increase on the permeation route in the water molecules in the g-PBAT polymer matrix.",
    url = "https://www.mdpi.com/2073-4360/14/13/2742/pdf?version=1657005783",
    doi = "10.3390/polym14132742",
    is_oa = "true",
    number = "13",
    pages = "2742",
    semanticscholar_citation_count = "11",
    semanticscholar_id = "7f345b3ad6cc6175b80d9d37e0e9554160d7ebfa",
    volume = "14"
}

Poly(lactic-co-glycolic acid) (PLGA) is a biocompatible, biodegradable polymer approved by the FDA and EMA, which is the most widely used in the field of health. In this study, PLGA was synthesized primarily from lactide and glycolide by polycondensation and ring-opening polymerization. Then, amino acid derivatives of PLGA were synthesized by the reaction of PLGA and amino acids in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). The polymers synthesized were PLGA, PLGA-L-glutamic acid (PLGA-G), and PLGA-L-aspartic acid (PLGA-A). The chemical structure of these polymers was confirmed by 1H and 13C Nuclear Magnetic Resonance (1H NMR and 13C NMR), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Gel Permeation Chromatography (GPC). When the 13C NMR analyses of PLGA-amino acid derivatives were observed, an increase in the number of carbonyl carbons around 170 ppm was found and the structure accuracy was supported. In addition, when the FTIR analyses of PLGA-amino acid derivatives were examined, the structure was confirmed by observing the signal of the amide bond carbonyl vibration at 1700 cm-1. While the typical endothermic thermogram of the PLGA-amino acid derivative structures was observed by DSC analysis, it was shown that the structures were low molecular weight polymers [~5000-6000 Da] by GPC analysis.

@article{doi1018185erzifbed1235522,
    author = "Önel, Gülce Taşkor",
    title = "Synthesis and Characterization of Poly(lactic-co-glycolic acid) Derived with LGlutamic Acid and L-Aspartic Acid",
    year = "2023",
    journal = "Erzincan Üniversitesi Fen Bilimleri Enstitüsü Dergisi",
    abstract = "Poly(lactic-co-glycolic acid) (PLGA) is a biocompatible, biodegradable polymer approved by the FDA and EMA, which is the most widely used in the field of health. In this study, PLGA was synthesized primarily from lactide and glycolide by polycondensation and ring-opening polymerization. Then, amino acid derivatives of PLGA were synthesized by the reaction of PLGA and amino acids in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). The polymers synthesized were PLGA, PLGA-L-glutamic acid (PLGA-G), and PLGA-L-aspartic acid (PLGA-A). The chemical structure of these polymers was confirmed by 1H and 13C Nuclear Magnetic Resonance (1H NMR and 13C NMR), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Gel Permeation Chromatography (GPC). When the 13C NMR analyses of PLGA-amino acid derivatives were observed, an increase in the number of carbonyl carbons around 170 ppm was found and the structure accuracy was supported. In addition, when the FTIR analyses of PLGA-amino acid derivatives were examined, the structure was confirmed by observing the signal of the amide bond carbonyl vibration at 1700 cm-1. While the typical endothermic thermogram of the PLGA-amino acid derivative structures was observed by DSC analysis, it was shown that the structures were low molecular weight polymers [\textasciitilde 5000-6000 Da] by GPC analysis.",
    url = "https://dergipark.org.tr/en/download/article-file/2894022",
    doi = "10.18185/erzifbed.1235522",
    is_oa = "true",
    number = "1",
    pages = "155-168",
    semanticscholar_citation_count = "3",
    semanticscholar_id = "5da38813a87c152208f5a0ad94a3a06c6e7191dd",
    volume = "16"
}