Histidine dipeptides

E. and Randaccio, L. (1992) Gold(III) glycyl-L-histidine dipeptide complexes. Preparation and x-ray structures of monomeric and cyclic tetrameric species. Inorganic Chemistry, 31, 1983 (b) Carotti, S., Marcon, G., Marussich, M., Mazzei, T., Messori, L., Mini, E. and Orioli, P. (2000) Cytotoxicity and DNA binding properties... 

CTABr + histidine dipeptides. Comparison of rates and enantioselectivities... 

Aristoy, M. C. and Toldra, F. (2004). Histidine dipeptides HPLC-based test for the detection of mammalian origin proteins in feeds for ruminants. Meat Sci. 67, 211-217. 

Johnson, P. and Hammer, J. L. (1992). Histidine dipeptide levels in aging and hypertensive rat skeletal and cardiac muscles. Comp. Biochem. Physiol. B Biochem. Mol. Biol. 103,981-984. 

Kim, N. H. and Kang, J. H. (2007). Protective effects of histidine dipeptides on the modification of neurofilament-L by the cytochrome c/hydrogen peroxide system. J. Biochem. Mol. Biol. 40,125-129. 

In the solid state, 4(5)-nitro-5(4)-methoxyimidazole exists as a 1 1 mixture of the two prototropic annular tautomers <2004AXB191>. However, in histidine-dipeptides, the tautomer equilibrium (N -H vs. N -H) has been found to vary depending on the nature of the peptide structures <2005JA12544>. 

In the MAS NMR spectra of histidine-dipeptides, the C chemical shifts for and C span a large range (up to 13 ppm) and are highly influenced by the tautomer effect and intermolecular interactions <2005JA12544>. The imidazole ring chemical shifts of 50 (158.6, 123.8 (Vcf = 36.0), 131.0 ppm, Scheme 14) resemble more closely those of l-methyl-5-(/i-tolyl)-4-trifluoromethyl-l//-imidazole (137.6, 128.8 ( cF = 37.4Hz), 133.0ppm). Based on this observation, it was proposed that in the solid state 50 most likely assumes the tautomeric form 50a rather than 50b <2001JHC773>. 

Cheng, F., Sun, H.H., Zhang, Y., Mukkamala, D., Oldfield, E. Solid state 13C NMR, crystallographic, and quantum chemical investigation of chemical shifts and hydrogen bonding in histidine dipeptides. J. Am. Chem. Soc. 2005, 127,12544-54. 

The ESR spectrum for cupric ion bound to four equivalent imidazoles from carnosine ()8-alanyl-L-histidine dipeptide) in frozen solution shows the quality of information that can typically be obtained [233] (Fig. 15, top spectrum). The intense line on the right split by at least nine hyperfine lines is the gj feature resolved due to hyperfine splitting to copper and to nitrogen donor atoms. Three of the four copper hyperfine lines in the gy (2.25) region (left side) are observable with y4 [ = 175 G. The remaining ESR parameters can be estimated and confirmed by computer simulation. These values for carnosine aregy = 2.06, Af = 15 G and /4 = 15 G. For comparison, data for cupric ion bound to hemoglobin at the N-terminus are gy = 2.210, = 2.050,... 

Amines (poly-, amino acids, histidine dipeptides)... 

Food products contain less copper than iron copper is mainly bound to protein as in ceruloplasmin. Copper ions are also chelated by albumin in mammalian and avian skeletal muscles and brain, they are chelated by camosine, anserine, and other histidine dipeptides. Cu + ions are more reactive than Fe ions and decompose hydrogen peroxide to produce hydroxyl radicals at a rate over 50 times higher than Fe + (Decker, 2001). However, the mechanism of the prooxidative effects of copper is most likely a mechanism other than that for iron, which is the reason why prevention of that catalysis in food systems requires a different strategy (Hultin, 1994). 

Most of the copper present in animal tissues is inactivated by chelation or binding to proteins in the form of cemloplasmin, albumin, carnosine and other histidine-dipeptides. These chelating compounds are good inhibitors of lipid oxidation in meat and fish. Carnosine present in muscle tissues can also reduce ferryl to oxymyoglobin. 

Muscle tissues contain a multi-component antioxidant system consisting of lipid-soluble compounds (a-tocopherol, ubiquinone), water-soluble compounds (ascorbate, histidine-dipeptides) and enzymes (superoxide dismutase, catalase, glutathione peroxidase). Lipid oxidation in meats can be effectively controlled by the use of various phenolic compounds derived from spice extracts, by vitamin E supplementation of animal diets, and by processing of cured meat with sodium nitrite. Various natural antioxidant formulations containing mixtures of tocopherols, ascorbyl palmitate and citric acid show synergistic effects in stabilizing cooked and frozen meat. Synthetic antioxidants, BHA, TBHQ, propyl gallate (see Chapter 9) and combinations with citric acid, ascorbic acid or phosphates are also effective formulations used to retard lipid oxidation in... 

In addition to a-amino acids, P- and y-amino acids can also be found in food. Naturally occurring P-alanine (3-aminopropionic add, 2-10) acts in the biosynthesis of pantothenic add, acetyl coenzyme A, other acyl coenzymes A (see Section 5.9.1) and some histidine dipeptides. P-Alanine is synthesised in several different ways, by aspartic add decarboxylation (in bacteria), but also by the transformation of propionic acid (in bacteria and some plants), by degradation of the polyamines spermine and spermidine (in yeasts and many plants, such as tomato, soybean and maize), or arising from the pytirnidine derivative uracil that occurs in aU animals and in some plants, such as wheat. 

Table 2.5 Histidine dIpeptIdes content of fresh meat.

In addition to proteins, the other nitrogen compounds present in meat are free amino acids. The level of the individual amino acids is about 0.005% (their total amount is 0.1-0.3%) alanine (about 0.01%), glutamic acid (about 0.05%) and taurine (0.02-0.1%) occur in somewhat higher concentrations, followed by histidine dipeptides and guanidine compounds such as creatine and creatinine. Important groups of nitrogenous compounds are purine and... 

Carnegie P.R., Ilk M.Z., Etheridge M.O., Collins M.G. Improved high-performance liquid chromatographic method for analysis of histidine dipeptides anserine, carnosine and balenine present in fresh meat. Journal of Chromatography, 261 153-157 (1983). 

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