Carbohydrates, compositional analysis

R.K. Merkle, I. Poppe, Carbohydrate composition analysis of glycoconjugates by GLC-MS, Methods EnzymoL, 230 (1994) 1. 

Merkle RK, Poppe I (1993) Carbohydrate composition analysis of glycoconjugates by gas-liquid chromatography/mass spectrometry. In (ed) Methods enzmol, vol 230. Academic Press, NY, pi... 

Recent applications of HPAEC-PAD are many and varied. A representative list includes quantitation of polyglucose metabolites in plasma of dialysis patients,148 analysis of heat-treated milk,149 carbohydrate content in lipopolysaccharides,150 phosphorylated sugars in tissue samples,151 composition of soybean meal,152 carbohydrate composition of recombinant modified tissue plasminogen activator,153 analysis of cyclization products from an enzyme reaction,154 carbohydrate content of glycoconjugate vaccines,155 and monitoring of patients with rheumatoid arthritis.156... 

An excellent review on protein hydrolysis for amino acid composition analysis has been published by Eountoulakis and Lahm [190], Hydrolysis can be performed by either chemical (under either acidic or basic conditions) or enzymatic means. The acidic hydrolysis itself can be carried out in a liquid or a gas-phase mode. The conventional acid hydrolysis uses 6M HCl for 20-24 h at 110°C under vacuum [200], In these conditions, asparagine and glutamine are completely hydrolyzed to aspartic acid and glutamic acid, respectively. Tryptophan is completely destroyed (particularly in the presence of high concentrations of carbohydrate), while cysteine and sometimes methionine are partially oxidized. Tyrosine, serine, and threonine are partially destroyed or hydrolyzed and correction factors have to be applied for precise quantification [190,201],... 

The two preparations from A. oryzae reportedly differ in amino acid and carbohydrate composition. The enzyme prepared by Minato contained 25% carbohydrate no cysteine was detected either by titration with p-mercuribenzoate in 6M urea or by cysteic acid analysis after performic acid oxidation (179). In contrast, Wolfenden et al. (92) reported 14 cysteine residues per mole of enzyme which reacted instantaneously with p-mercuribenzoate in the absence of urea. No explanation is available for this apparent discrepancy. 

Structural Analyses Of Gangliosides. Carbohydrate composition, methylation analysis, enzyme treatment and partial acid hydrolysis were performed as described previously (9). 

From a nutritional viewpoint, it is necessary to stress the current importance of carrying out the multielemental analysis of milk samples (either human, cow s, or formula milk) in order to establish the reference values of essential elements and quantify the levels of potentially toxic elements. This fact is more relevant to formula milk production for premature babies as some essential elements are not stored by the fetus during its development in the uterus. Attention has been already paid to the qualitative and quantitative composition (analysis) of proteins, lipids, carbohydrates, and, of course, essential elements. However, in the case of human nutrition, knowledge on the particular species (compounds) in which a given element is present (chemical speciation) is now urgently needed, because the absorption and bioavailability of the essential element will strongly depend on that particular chemical form. Thus, although only the total element daily requirements have been considered here, it is important to stress that more attention must be paid to the chemical form in which essential and potentially toxic elements are present in milk. Such aspects are dealt with in detail in Chapter 13 by B. Michalke et al. 

Obviously inspired by these projects, Moyna et al, [80] investigated the dissolution of banana pulp in [bmim]Cl via 13C NMR spectroscopy. They found substantial variations in the carbohydrate composition for different samples which could potentially be used for the analysis of fruit ripening. 

Compositional analysis of some N-linked chains from membrane glycoproteins in Dictyostelium also show the presence of xylose residues [23]. Carbohydrate-specific monoclonal antibodies against several developmentally regulated glycoproteins are competed by horseradish peroxidase which is known to carry both p-Xyl and a-Fuc residues... 

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