Glycine systems

The complexes of four oxime analogs of amino acids (N-pyruvoyl amino acid oximes) with Bu2SnO were prepared. The ligands are coordinated to the tin centers by monodentate -COO , and oxime N atoms and Oh or Tbp species are formed.Similar studies were performed on the MeSn(IV)-SalGly (salycil-glycine) system. ... 

For the glycine system, models I and II in Table 43 have been suggested.581 But (c/. Section 33.5.5.1.ii), for pH >5 other V02+ hydrolysis products should be included.585,588 For the L-alanine system (certainly similar to glycine), results were explained according to model III included in Table 43. [VO(HAlaO)2+] (119) must be included to explain the CD spectra. The inclusion of (124) gives a better fit of the data. 

Kinetic studies have concentrated on the glycine system.1174,1175,1176 In the pH range 3.0-3.8 (40 °C), the reaction proceeds by acid-dependent and -independent paths reaction via the hydroxy complex is probably la, whereas the aqua complex appears to undergo /a substitution. 

In a series of experiments in which the sugar was increasingly replaced by 2-furaldehyde in the n-xylose-glycine system, color formation increased with the initial amount of the furan added. It was concluded that both the sugar and the furan contribute to browning.101 Other experiments also... 

Volatiles from Amino Acid + Ribose alone. All the reaction systems produced complex mixtures of volatiles, containing large numbers of heterocyclic compounds, many of which have not been reported previously in Maillard systems. In the absence of phospholipid 74 compounds were separated and identified from the glycine system (21) furfurals and furanylketones dominated and the three largest peaks in the chromatogram were 2-furfural [1], dimethylfurfural [2] and ethylmethylfurfural [3]. 

When a xylose-glycine system is heated under reflux in 0.07 M phosphate buffer, pH 8.2, cooled and extracted first with light petroleum (b.p. 60-80 °C), and then with ether, the latter extract contained many fluorescent compounds amongst the large number of components separated by HPLC.113 Two types of fluorescence spectra stood out because of their repeated occurrence ... 

Mundt el al.n9 have adapted the above scheme for the maltose-glycine system (pH 5.5, 70 °C). Multiresponse modelling gave excellent fits for the time course of the concentrations of glucose, melanoidins (A470, number of maltose molecules incorporated from U-14C-labelled maltose), 3-DH (as quinoxaline derivative), maltose, and SIV (in maltose-glycine-SIV systems). 

The derived rate constants were applied to the glucose-glycine system, where a good fit was obtained. In accord with the above scheme, ARP and 3-DG were formed simultaneously, while there was a lag phase for colour (melanoidins, M) and 1-DG. 3-DG proved to be the main pathway for colour formation. 

More than 20 pyridines from 13 systems have been tabulated by Vemin and Parkanyi.216 They arise mainly during the thermal degradation of sulfur-containing amino acids alone or in the presence of glucose. They are also formed in glu-cose-proline systems, on degradation of Amadori intermediates of the glucose-glycine system, and on pyrolysis of a- and /1-alanine. 

Anese, M., Nicoli, M.C., and Lerici, C.R. 1994. Influence of pH on the oxygen scavenging properties of heat-treated glucose-glycine systems. Ital. J. Food Sci. 3, 339-343. 

Pyne A, Chatterjee K, Suryanarayanan R. Solute crystallisation in mannitol-glycine systems. Implications on protein stabilisation in freeze-dried formulations. / Pharm Sci 2003 92(11) 2272-2283. 

For the glycinate system, increase the concentration of gly- to 0.2 M (50-fold excess)—note total ionic strength will be changed. Run a scan. 

Photochemical conversion of an amino(cyclopropyl)carbene (obtained from cyclopro-pyl(methoxy)carbene with optically pure D,i.-erythro amino alcohols) gave a cyclopropyl-substituted lactone, e.g. formation of 13, which upon hydrogenolysis gave a chiral cyclopropyl-glycine system.The reaction proceeds via a ketene complex. 

Pasternack and co-workers have reported a series of detailed temperature-jump studies on mixed ligand complexes involved in the copper(ll) + bipyridine + glycine system [142], the copper(ll) + bipyridine + ethylene-diamine, of-alanine, and j3-alanine systems, and the cobalt(ll) + bipyridine + glycine system [143]. 

Focused proteins are separated according to their molecular weight in 12.5% acrylamide and 2.6% bis-acrylamide polyacrylamide gels using the Tris-glycine system (see Note 8). 

The turnover of glycine can in principle be monitored from the incorporation of label in serine and glycine after infusion with [3,4- C]-glucose or after intracerebral injection of labeled serine There are no reports in the literature on a serious evaluation of this approach after pharmacological treatment of the glycine system. 

Table 2.1.2. Relative energies (in Kcal/mol) for the complexes formed between a molecule of water with the neutral glycine (NE-H20), the zwitterion (ZW H20), and the state of transition (TS-H2O), as well as for the neutral glycine system and independent molecule of water (NE+H20)> obtained with a base HF/6-31+G ...

Figure 2 Adiabatic combustion temperature in metai-nitrate glycine systems...

Transamination between oxo- and amino-acids is one of the enzymatic reactions that can be duplicated in metal ion model systems (1-4). The reactive intermediates appear to be "mixed complexes in which it is thought the ligands are condensed as Schiff bases. Recently, ways of applying pH-titration techniques to these systems and analyzing the data using high speed computers have been proposed (5). This earlier study (5) which concerned the Ni(II)-pyruvate-glycinate system has been extended to an examination of the Ca(II), Mn(II) and Zn(II) systems at 25 . An attempt was also made to obtain the heats and entropies of formation of the Mn(II), Ni(Il) and Zn(II) complexes from additional titrimetric data at 10 and 40 . 

These and other problems caused Letter and Jordan to reconsider the assumptions used to reduce the complete rate law. Is it reasonable that ki t If one uses the Ni(II)-glycine system for analysis, then an estimate of i( 2i HI can be obtained from the corresponding nickel(II)-acetate system, and ((HjhOsCo—OjCCHjNHj ) can be used to estimate that K[ 3xlO °M. Tlien, the condition that k k2t[H l pH 6 requires that Jfejj 10 s . However, k = 3x10 s" for water exchange on Ni(II), and all the available evidence indicates an mechanism for substitution on Ni(II). Therefore, if is 10 s th die water ligands in the monodentate intermediate must be labilized by about a factor of 10, an effect that is without precedent... 

Patton, S. The formation of maltol in certain carbohydrate-glycine systems. J. Biol. Chem. 1950,184, 131—135. 

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