Carbohydrates interactions with metal ions

In order to investigate these interactions, C-n.m.r. spectroscopy has been used to study the binding of the metal ions to various carbohydrate residues and glycopeptides, and to extract information on the specific binding-sites of the carbohydrate residues, in order to define further how and why metal ions interact with certain residues in biological systems. 

H.A. Tajmir-Riahi, Carbohydrate adducts with zinc group metal ions. Interaction of p-D-fructose with Zn(ll), Cd(ll) and Hg(II) cations and the effects of metal-ion coordination on the sugar isomer binding. Carbohydr. Res., 172(198) 1. 

The interaction of artificial metal ions/complexes with peptides/proteins [11], nucleic acids/DNA [12,13], enzymes [14], steroids [15] and carbohydrates [16] forms a bridge between natural and artificial macromolecular metal complexes. Biometal-organie chemistry concentrates on such complexes [17]. The reason for the increasing interest in this field lies in medical applications of metal complexes (cancer, photodynamic therapy of cancer, immunoassays, fluorescence markers, enantioselective catalysis, template orientated synthesis of peptides, etc.). Figure 2-4 presents an overview of metals in medicine [18]. Some examples are given below. 

Typical applications of ion exchange in sugar analysis include (a) complexation of borates, which accentuates ionic interactions with the exchanger (27), (b) use of hydroorganic eluents, especially acetonitrile/water, with rigid, fine-particulate anion columns (28), (c) use of basic eluents, since most carbohydrates are weak acids with pKfl of 12-13 (29), (d) complexation with cations, Pb2+, Ca2+ and Ag+ being the most frequently employed, (e) the use of cation exchangers in a heavy metal form, e.g., Aminex HPX-85. 

The degradation of 2-deoxyribose by Fenton s reagent has been conducted in acidic, neutral, and alkaline media, and in the presence and absence of hydroxyl-radical scavengers. It seems that both the substrate and the scavengers interact with the metal ions.110 Traces of Fe(II) accelerate the oxidation of carbohydrates by H202, but larger quantities of such a cation has a retarding elfect.111... 

When metal ions are used as counter ions, instead of organic quaternary ammonium ions, in the packing material, the hydroxy (-OH-) fimctional groups of the carbohydrates and other sugars interact with these metals ion. Pb, Ca, and Na, are typical metal ions in the packing material. Depending upon the type of counter ions used, the intensity of the interaction changes and therefore, the retention between different carbohydrates vary. Some of the carbohydrates are also retained because of the size of the molecule under these conditions. 

NUCLEAR MAGNETIC RESONANCE-SPECTRAL STUDIES OF THE INTERACTIONS OF METAL IONS WITH CARBOHYDRATES USE OF RELAXATION PROBES... 

The interaction of metal ions with carbohydrates has been a topic of interest for a number of years. In any biological system, calcium ions and... 

Inositols provide a good starting-point for studying the binding of such metal ions as Gd " " and Mn " to carbohydrates, because each is unique, they are structurally related to carbohydrates, and they do not contain other functional groups (carboxyl, amino) which may also interact with metal... 

Study of the interactions of Gd with compounds 17-20 answered questions concerning the role that the peptide bond plays in the metal-ion binding-site. Furthermore, this study clearly distinguished the metal-ion-carbohydrate and metal-ion-peptide interactions. 

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