TY - JOUR AU - Majer, Zsuzsanna (Deckerné) AU - Vass, Elemér AU - Roscic, Maja AU - Hollósi, Miklós AU - Horvat, Stefica AU - Jakas, Andreja TI - Metal-Binding Ability of Leu-Enkephalin, Related Glycoconjugates and Peptidomimetics JF - CROATICA CHEMICA ACTA J2 - CROAT CHEM ACTA VL - 88 PY - 2015 IS - 3 SP - 281 EP - 287 PG - 7 SN - 0011-1643 DO - 10.5562/cca2725 UR - https://m2.mtmt.hu/api/publication/3008464 ID - 3008464 AB - Both the chemistry and consequences of the nonenzymatic reaction between reducing sugars and reactive amino groups of amino acids, peptides and proteins (known as the Maillard reaction), have received considerable attention in food and health science fields. This initial reaction results in Amadori and similar products formation, followed by degradation to advanced glycation end products (AGEs). It is well established that AGEs are associated with color and odor of thermally processed or stored food, as well as with pathogen products in a number of diseases. The model systems of early stage Maillard reaction products (MRP) were prepared between endogenous opioid peptide leucine enkephalin (1) and D-glucose/D-glucuronic acid. The complexation ability of prepared MRP with metal ions (Ca2+, Zn2+, Al3+, Pb2+ and Cu2+) was investigated and compared to the complexation ability of parent peptide using ECD and FTIR spectroscopic measurements. LA - English DB - MTMT ER - TY - JOUR AU - Knapp, Krisztina Nóra AU - Gorecki, M AU - Frelek, J AU - Luboradzki, R AU - Hollósi, Miklós AU - Majer, Zsuzsanna (Deckerné) AU - Vass, Elemér TI - Comprehensive Chiroptical Study of Proline-Containing Diamide Compounds JF - CHIRALITY: THE PHARMACOLOGICAL BIOLOGICAL AND CHEMICAL CONSEQUENCES OF MOLECULAR ASYMMETRY J2 - CHIRALITY VL - 26 PY - 2014 IS - 4 SP - 228 EP - 242 PG - 15 SN - 0899-0042 DO - 10.1002/chir.22305 UR - https://m2.mtmt.hu/api/publication/2578298 ID - 2578298 N1 - Funding Agency and Grant Number: Hungarian Scientific Research Fund OTKAOrszagos Tudomanyos Kutatasi Alapprogramok (OTKA); Hungarian Academy of SciencesHungarian Academy of Sciences; Polish Academy of Sciences; Central Hungarian Operational Program [K81175, K100720, 17, KMOP-4.2.1/B-10-2011-0002] Funding text: Contract grant sponsor: Hungarian Scientific Research Fund OTKA, the Hungarian Academy of Sciences and Polish Academy of Sciences, the Central Hungarian Operational Program; Contract grant numbers: K81175, K100720, HAS-PAN no 17, KMOP-4.2.1/B-10-2011-0002. AB - The continuously growing interest in the understanding of peptide folding led to the conformational investigation of methylamides of N-acetyl-amino acids as diamide models. Here we report the results of detailed conformational analysis on Ac-Pro-NHMe and Ac--HPro-NHMe diamides. These compounds were analyzed by experimental and computational methods, the conformational distributions obtained by Density Functional Theory (DFT) calculations for isolated and solvated diamide compounds are discussed. The conformational preference of proline-containing diamide compounds as a function of the ambience was observed by a number of chiroptical spectroscopic techniques, such as vibrational circular dichroism (VCD), electronic circular dichroism (ECD), Raman optical activity (ROA) spectroscopy, and additionally by single crystal X-ray diffraction analyses. Based on a comparison between Ac-Pro-NHMe and Ac--HPro-NHMe, one can conclude that due to the greater conformational freedom of the -HPro derivative, Ac--HPro-NHMe shows different behavior in solid- and solution-phase, as well. Ac--HPro-NHMe tends to form cis Ac--HPro amide conformation in water, dichloromethane, and acetonitrile in contrast to its -Pro analog. On the other hand, the crystal structure of the -HPro compound cannot be related to any of the conformers obtained in vacuum and solution while the X-ray structure of Ac-Pro-NHMe was identified as t(L)-, which is a trans Ac-Pro amide containing conformer also predominant in polar solvents. Chirality 26:228-242, 2014. (c) 2014 Wiley Periodicals, Inc. LA - English DB - MTMT ER - TY - JOUR AU - Konar, AD AU - Vass, Elemér AU - Hollósi, Miklós AU - Majer, Zsuzsanna (Deckerné) AU - Grüber, G AU - Frese, K AU - Sewald, N TI - Conformational properties of secondary amino acids: Replacement of pipecolic acid by N-methyl-L-alanine in efrapeptin C JF - CHEMISTRY & BIODIVERSITY J2 - CHEM BIODIVERS VL - 10 PY - 2013 IS - 5 SP - 942 EP - 951 PG - 10 SN - 1612-1872 DO - 10.1002/cbdv.201300086 UR - https://m2.mtmt.hu/api/publication/2465435 ID - 2465435 AB - The efrapeptins, a family of naturally occurring peptides with inhibitory activities against ATPases, contain several α,α-disubstituted α-amino acids such as α-aminoisobutyric acid (Aib) or isovaline (Iva) besides pipecolic acid (Pip), β-Ala, Leu, Gly, and a C-terminal heterocyclic residue. Secondary α-amino acids such as proline are known to stabilize discrete conformations in peptides. A similar influence is ascribed to N-alkyl α-amino acids. We synthesized two efrapeptin C analogs with replacement of Pip by N-methyl-L-alanine (MeAla) using a combination of solid- and solution-phase techniques in a fragment-condensation strategy to compare the conformational bias of both secondary amino acids. The solution conformation was investigated by vibrational circular dichroism (VCD) to probe whether the analogs adopt a 310-helical conformation. The MeAla-containing analogs [MeAla1,3]efrapeptin C and [MeAla1,3,11]efrapeptin C inhibit ATP hydrolysis by the A3B3 complex of A 1A0-ATP synthase from Methanosarcina mazei Gö1. Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich. LA - English DB - MTMT ER - TY - JOUR AU - Majer, Zsuzsanna (Deckerné) AU - Szilvágyi, Gábor AU - László, Benedek AU - Csámpai, Antal AU - Hollósi, Miklós AU - Vass, Elemér TI - Chelate Structure of a Dirhodium–Amino Acid Complex Identified by Chiroptical and NMR Spectroscopy JF - EUROPEAN JOURNAL OF INORGANIC CHEMISTRY J2 - EUR J INORG CHEM VL - 2013 PY - 2013 IS - 17 SP - 3020 EP - 3027 PG - 8 SN - 1434-1948 DO - 10.1002/ejic.201300057 UR - https://m2.mtmt.hu/api/publication/2382937 ID - 2382937 LA - English DB - MTMT ER - TY - JOUR AU - Szilvágyi, Gábor AU - Brem, B AU - Bati, G AU - Tölgyesi, László AU - Hollósi, Miklós AU - Vass, Elemér TI - Dirhodium complexes: determination of absolute configuration by the exciton chirality method using VCD spectroscopy. JF - JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS J2 - J CHEM SOC DALTON TRANS VL - 42 PY - 2013 IS - 36 SP - 13137 EP - 13144 PG - 8 SN - 1472-7773 DO - 10.1039/c3dt51567b UR - https://m2.mtmt.hu/api/publication/2382936 ID - 2382936 AB - Inherently chiral dinuclear rhodium complexes have been synthesized from the well-known dirhodium(ii)-acetate and chiral/achiral amino acids. These complexes have a twisted paddlewheel structure due to axial chirality. Chiral induction could be observed when the ligands were chiral, opposite to the case of achiral ligands, where a racemic mixture was formed. The racemic mixture was separated by chiral HPLC-ECD. The stereochemical properties of these complexes were determined by VCD spectroscopy supported by theoretical calculations at the DFT level. We present a simple route to determine the absolute configuration by an exciton chirality method using VCD spectroscopy. LA - English DB - MTMT ER - TY - JOUR AU - Knapp, Krisztina Nóra AU - Hollósi, Miklós AU - Vass, Elemér AU - Majer, Zsuzsanna (Deckerné) TI - Vibrational and chiroptical spectroscopic investigation on diamide peptide models JF - JOURNAL OF PEPTIDE SCIENCE J2 - J PEPT SCI VL - 18 PY - 2012 IS - 1 SP - S173 EP - S173 SN - 1075-2617 UR - https://m2.mtmt.hu/api/publication/2711350 ID - 2711350 N1 - SU 1 LA - English DB - MTMT ER - TY - JOUR AU - Hollósi, Miklós AU - Knapp, Krisztina Nóra AU - Majer, Zsuzsanna (Deckerné) AU - Szilvágyi, Gábor AU - Vass, Elemér TI - A VCD-spektroszkópia alkalmazása peptidek, peptidmimetikumok és királis átmenetifém-komplexek térszerkezetének felderítésében JF - MAGYAR KÉMIAI FOLYÓIRAT - KÉMIAI KÖZLEMÉNYEK (1997-) J2 - MAGY KÉM FOLY KÉM KÖZL VL - 118 PY - 2012 IS - 2-4 SP - 145 EP - 150 PG - 6 SN - 1418-9933 UR - https://m2.mtmt.hu/api/publication/2382940 ID - 2382940 LA - Hungarian DB - MTMT ER - TY - JOUR AU - Weigelt, S AU - Huber, T AU - Hofmann, F AU - Jost, M AU - Ritzefeld, M AU - Luy, B AU - Freudenberger, C AU - Majer, Zsuzsanna (Deckerné) AU - Vass, Elemér AU - Greie, JC AU - Panella, L AU - Kaptein, B AU - Broxterman, QB AU - Kessler, H AU - Altendorf, K AU - Sewald, N AU - Hollósi, Miklós TI - Synthesis and Conformational Analysis of Efrapeptins JF - CHEMISTRY-A EUROPEAN JOURNAL J2 - CHEM-EUR J VL - 18 PY - 2012 IS - 2 SP - 478 EP - 487 PG - 10 SN - 0947-6539 DO - 10.1002/chem.201102134 UR - https://m2.mtmt.hu/api/publication/2018509 ID - 2018509 N1 - VL 18 AB - The efrapeptin family of peptide antibiotics produced by the fungus Tolypocladium niveum, and the neo-efrapeptins from the fungus Geotrichum candidumare inhibitors of F1-ATPase with promising antitumor, antimalaria, and insecticidal activity. They are rich in Ca-dialkyl amino acids (Aib, Iva, Acc) and contain one beta-alanine and several pipecolic acid residues. The C-terminus bears an unusual heterocyclic cationic cap. The efrapeptins CG and three analogues of efrapeptin C were synthesized using a-azido carboxylic acids as masked amino acid derivatives. All compounds display inhibitory activity toward F1-ATPase. The conformation in solution of the peptides was investigated with electronic CD spectroscopy, FT-IR spectroscopy, and VCD spectroscopy. All efrapeptins and most efrapeptin analogues were shown to adopt helical conformations in solution. In the case of efrapeptin C, VCD spectra proved that a 310-helix prevails. In addition, efrapeptin C was conformationally studied in detail with NMR and molecular modeling. Besides NOE distance restraints, residual dipolar couplings (RDC) observed upon partial alignment with stretched PDMS gels were used for the conformational analysis and confirmed the 310-helical conformation. LA - English DB - MTMT ER - TY - JOUR AU - Vajda, T AU - Hollósi, Miklós TI - FREEZING EFFECT ON CHIRALITY AMPLIFICATION OF L-ASPARAGINE BY CRYSTALLIZATION OF THE RACEMATE IN PREFERENTIAL CONDITION JF - CRYOLETTERS J2 - CRYOLETTERS VL - 32 PY - 2011 IS - 6 SP - 447 EP - 450 PG - 4 SN - 0143-2044 UR - https://m2.mtmt.hu/api/publication/2284925 ID - 2284925 AB - The role of freezing in stereoselection by crystallization of a saturated DL-asparagine solution in preferential condition of L-asparagine, has been investigated. To this end, the L-asparagine excess obtained by crystallization and then kept of different lengths of time at -20 degrees C in frozen aqueous solution was analyzed. The samples of the yielded materials were derivatised according to Marfey's method (see text). These derivatives were traced and evaluated by RP-HPLC analysis. The relatively best effects appeared after a one day treatment, where the freezing induced asymmetry amplifications and it increased the L-enantiomer excess from 10 mol % to 34.9, 35.0 and 35.5 mol go, respectively. Here we provide the first example of the influence of freezing on chirality amplification by preferential crystallization. Also some speculations are made about the implications of our findings in the prebiotic events of L-amino acids. LA - English DB - MTMT ER - TY - JOUR AU - Szilvágyi, Gábor AU - Majer, Zsuzsanna (Deckerné) AU - Vass, Elemér AU - Hollósi, Miklós TI - Conformational Studies on Chiral Rhodium Complexes by ECD and VCD Spectroscopy JF - CHIRALITY: THE PHARMACOLOGICAL BIOLOGICAL AND CHEMICAL CONSEQUENCES OF MOLECULAR ASYMMETRY J2 - CHIRALITY VL - 23 PY - 2011 IS - 4 SP - 294 EP - 299 PG - 6 SN - 0899-0042 DO - 10.1002/chir.20916 UR - https://m2.mtmt.hu/api/publication/1504473 ID - 1504473 LA - English DB - MTMT ER -