Metall-amino

In conventional systems, feeds are supplemented with minerals and vitamins. Studies indicate that supplementing the winter feed of cows leads to enhanced levels of Ca, P, Mg, Na, K, and particularly Cu, in the milk of cows receiving a metal amino acid chelate and vitamins (Strusinska et al., 2004). 

Controllable Assembly, Structures, and Properties of Lanthanide-Transition Metal-Amino Acid Clusters... 

Abstract Amino acids are the basic building blocks in the chemistry of life. This chapter describes the controllable assembly, structures and properties of lathanide(III)-transition metal-amino acid clusters developed recently by our group. The effects on the assembly of several factors of influence, such as presence of a secondary ligand, lanthanides, crystallization conditions, the ratio of metal ions to amino acids, and transition metal ions have been expounded. The dynamic balance of metalloligands and the substitution of weak coordination bonds account for the occurrence of diverse structures in this series of compounds. 

Amino acid is one of the most important biological ligands. Researches on the coordination of metal-amino acid complexes will help us better understand the complicated behavior of the active site in a metal enzyme. Up to now many Ln-amino acid complexes [50] and 1 1 or 1 2 transition metal-amino acid complexes [51] with the structural motifs of mononuclear entity or chain have been synthesized. Recently, a series of polynuclear lanthanide clusters with amino acid as a ligand were reported (most of them display a Ln404-cubane structural motif) [52]. It is also well known that amino acids are useful ligands for the construction of polynuclear copper clusters [53-56], Several studies on polynuclear transition metal clusters with amino acids as ligands, such as [C03] [57,58], [Co2Pt2] [59], [Zn6] [60], and [Fe ] [61] were also reported. 

Except for the factors mentioned above, such as the reactant ratio employed, variation of lanthanide and transition metal, crystallization conditions, and the presence of a secondary ligand, there are several other factors that can affect the controllable assembly of the lanthanide-transition metal-amino acid cluster compounds. 

Up until the time of publication of reference 38, there had been few modeling studies of metal-amino acid, metal-protein, metal-nucleotide, or metal-nucleic... 

Figure 18. Schematic representation of bidentate (transition metal) - (amino acid) chelate complex formations.

Ahrens, L. H., "Ionization Potentials and Metal-Amino Acid Complex... 

Table 2 Log Formation Constants of Some Metal Amino Acid Complexes in Aqueous Media4... 

In more recent years attention has turned from studying the equilibria of binary metal-amino acid complexes to that of ternary complex formation in aqueous media, particularly to complexes of the type (aa)—M11—L, where L is some other ligand or a different amino acid to (aa), and M11 is a kinetically labile metal ion. Ternary complexes involving kinetically inert metal ions, e.g. Co,w and Pt", are more well known since they can be separated from mixtures and studied in isolation. Such is not the case with the labile systems. Because of the facile nature of their equilibria they must be studied in situ (claims regarding the separation of labile species by chromatographic procedures... 

Molecular mechanics and dynamics studies of metal-nucleotide and metal-DNA interactions to date have been limited almost exclusively to modeling the interactions involving platinum-based anticancer drugs. As with metal-amino-acid complexes, there have been surprisingly few molecular mechanics studies of simple metal-nucleotide complexes that provide a means of deriving reliable force field parameters. A study of bis(purine)diamine-platinum(II) complexes successfully reproduced the structures of such complexes and demonstrated how steric factors influenced the barriers to rotation about the Pt(II)-N(purine) coordinate bonds and interconversion of the head-to-head (HTH) to head-to-tail (HTT) isomers (Fig. 12.4)[2011. In the process, force field parameters for the Pt(II)/nucleotide interactions were developed. A promising new approach involving the use of ab-initio calculations to calculate force constants has been applied to the interaction between Pt(II) and adenine[202]. 

Enantioselective metal chelation is a technique that has been applied to the separation of amino acid enantiomers. In the method, a transition metal-amino acid complex, such as copper(II)-aspartame, in which the full coordination of the complex has not been reached, is added to the buffer. The amino acid enantiomers are able to form ternary diastereomeric complexes with the metal-amino acid additive if there are differences in stability between the two complexes, enantioselective recognition can be achieved. 

The use of mixed micelles for chiral recognition was discussed in Section 5.3.3, using cyclodextrins. In addition to cyclodextrins, however, metal-amino acid complexes can also be used in a mixed mode arrangement. Bile salts are naturally occurring chiral surfactants that can be used as alternatives to, or in addition to, SDS for chiral recognition. In the presence of SDS, the migration times are faster. Table 5.5 shows initial operating conditions that can be used in chiral CE as a start to methods development.40... 

Incompatible with halides anionic emulsifying agents and suspending agents tragacanth starch talc sodium metabisulfite sodium thiosulfate disodium edetate silicates aluminum and other metals amino acids ammonia and ammonium salts sulfur compounds rubber and some plastics. 

Threonine and allothreonine are thermally unstable amino acids. The same is true for the simplest hydroxy amino add, (S)-serine (39). High levels of this amino add have however been reported from certain petroleum brine waters and its preservation may be due to the formation of stable chelates. Ahrens has suggested that metal-amino acid chelates may be important in the sedimentary cycle, and the uptake of certain metals in sediments, particularly in binding of metal-amino acid chelates to clays, has been proposed as a possible mechanism for the incorporation of metal ions in carbonaceous materials. Similar complexes are thought to contribute to the stabilization of amino acids in coals, lignites and peats, but, as has been outlined in a previous section, many other ligands are also present in these media, and their relative importance is difScult to assess. Much of this work is unfortunately of a speculative nature since no well-characterized complex of an amino acid has been isolated from a geological source, as far as the author is aware. 

A chiral stationary phase is used comprising a silica substrate on which is fixed an amino acid. The mechanisms developed are of the "ligand exchange" type. The distinction between two enantiomers is possible due to the formation of mixed diastereoisomerical complexes (chiral solute - transition metal - amino acid fixed on the silica substrate). The transition metal is added to the mobile phase. (Fig. 4)... 

Klabunovskii, E.L, Pavlov, V.A., and Fridman, Ya.D. (1984) On chiro-diastaltic interaction in mixed complexes metal-amino acid-diketone (ketoester), Izv. AN SSSR Ser. khim., 1005-1010, Chem. Abstr. 1984, 101, 79240p. 

Spectrophotometric methods have been applied to inclusion complexes of a-and p-CDs with methyl orange (in the presence of alcohols). A report on a symposium on spectroscopic and thermodynamical studies of metal-amino sugar complexes was published. Electronic absorption and fluorescence spectra of L-ascrobic acid have been studied at a range of pH values. ... 

Study of the structures of metal-amino acid complexes is a classical problem initiated by the school of Pauling in the 40s, with the nickel-glycine compound. Many authors have worked in this direction with increasing resolution and details. This paper describes the single-crystal structure of [bis(L-alaninato)diaqua] Nickel(II) dihydrate. 

Metal amino acid complex The product resulting from complexing of a soluble metal salt with an amino acid. 

Metal amino acid chelate The product of the reaction of a metal ion from a soluble metal salt with amino acids with a mole ratio of one mole of metal to three moles (preferably two) of amino acids to form coordinate covalent bonds. The average weight of the hydrolysed amino acids must be approximately 150 and the resulting molecular weight of the chelate must not exceed 800. 

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