RESUMEN
The crystal structures of two salts, products of the reactions between [(5-methyl-2-pyridyl)aminomethylene]bis(phosphonic acid) and 4-aminopyridine or ammonia, namely bis(4-aminopyridinium) hydrogen [(5-methyl-2-pyridinio)aminomethylene]diphosphonate 2.4-hydrate, 2C(5)H(7)N(2)(+).C(7)H(10)N(2)O(6)P(2)(2-).2.4H(2)O, (I), and triammonium hydrogen [(5-methyl-2-pyridyl)aminomethylene]diphosphonate monohydrate, 3NH(4)(+).C(7)H(9)N(2)O(6)P(2)(3-).H(2)O, (II), have been determined. In (I), the Z configuration of the ring N-C and amino N-H bonds of the bisphosphonate dianion with respect to the C(ring)-N(amino) bond is consistent with that of the parent zwitterion. Removing the H atom from the pyridyl N atom results in the opposite E configuration of the bisphosphonate trianion in (II). Compound (I) exhibits a three-dimensional hydrogen-bonded network, in which 4-aminopyridinium cations and water molecules are joined to ribbons composed of anionic dimers linked by O-H...O and N-H...O hydrogen bonds. The supramolecular motif resulting from a combination of these three interactions is a common phenomenon in crystals of all of the Z-isomeric zwitterions of 4- and 5-substituted (2-pyridylaminomethylene)bis(phosphonic acid)s studied to date. In (II), ammonium cations and water molecules are linked to chains of trianions, resulting in the formation of double layers.
Asunto(s)
4-Aminopiridina/química , Amoníaco/química , Organofosfonatos/química , Piridinas/química , Cristalografía por Rayos X , Difosfonatos/química , Enlace de Hidrógeno , Conformación Molecular , Sales (Química) , EstereoisomerismoRESUMEN
INTRODUCTION: Advanced glycation end-products play an important role in diseases related to diabetes and aging processes. Model compounds are synthesized in order to prepare the diagnostic and experimental tools for studying the mechanisms of pathogenesis. The objective of the present study was to accelerate glycation and upgrade its efficiency under high-pressure conditions. MATERIAL/METHODS: Aqueous solutions of proteins were kept with carbohydrates under a pressure of up to 850 MPa for several hours. Then the high-pressure glycation (HPG) products were fractionated on a Sephadex G-200 column and characterized with SDS-PAGE and MALDI-TOF mass spectrometry. RESULTS: The low-molecular-mass fraction of glycated proteins was separated from the two fractions containing high-and intermediate-molecular-mass cross-linked products of glycation. The products were then compared with those obtained with the high-temperature glycation (HTG) procedure carried out in dry conditions with a lyophilized mixture of substrates. The fractionated products were used to prepare rabbit sera. CONCLUSIONS: The immunoblotting experiments showed that the epitopes on the cross-linked glycation products formed in solution under high pressure differed from those originating in dry conditions at high temperature. Sera against the HPG products were specific to homologous material and did not interact with the fractions obtained by HTG. The antibodies against HTG products recognized HTG but not HPG products.