Amino acids and derivatives, analysis

CHROMATOGRAPHIC APPLICABILITY SPECTRUM 1.8.1 Analysis of Amino Acids and Derivatives... 

Leuchtenberger W, Huthmacher K, Drauz K (2005) Biotechnological production of amino acids and derivatives current status and prospects. J Appl Microbiol Biotechnol 69(1) 1-8 Levitsky VY, Lozano P, Iborra JL (1999) Kinetic analysis of deactivation of immobilized (x-chymotiipsin by water-miscible organic solvent in kyotorphin synthesis. Biotechnol Bioeng 65 170-175... 

Applications of the oxalate-hydrogen peroxide chemiluminescence-based and fluorescence-based assays with NDA/CN derivatives to the analysis of amino acids and peptides are included. The sensitivity of the chemiluminescence and fluorescence methods is compared for several analytes. In general, peroxyoxalate chemiluminescence-based methods are 10 to 100 times more sensitive than their fluorescence-based counterparts. The chief limitation of chemiluminescence is that chemical excitation of the fluorophore apparently depends on its structure and oxidation potential. 

Much of the recent work on the use of anodic amide oxidation reactions has focused on the utility of these reactions for functionalizing amino acids and for synthesizing peptide mimetics [13]. For example, in work related to the cyclization strategy outlined in Scheme 3, the anodic amide oxidation reaction has been used to construct a pair of angiotensin-converting enzyme inhibitors [14]. The retrosynthetic analysis for this route is outlined in Scheme 4. In this work, the anodic oxidation reaction was used to functionalize either a proline or a pipercolic add derivative and then the resulting methoxylated amide used to construct the bicyclic core of the desired inhibitor. A similar approach has recently been utilized to construct 6,5-bicyclic lactam building blocks for... 

Differences of <5 = 0.32-0.40 in the, 9F chemical shift for epimeric A -acylated Mosher derivatives of aliphatic a-amino acids, in particular alanine, as well as its amides and peptide derivatives, are sufficiently large to serve as a racemisation test23. However, high-field spectrometers are recommended to provide improved sensitivity (<0.5%). Table 19, representing analysis data taken at 376.5 MHz, can be found in Section 3.2.2.9. Analysis of absolute configuration of amino acids and amines can be more accurate using a modified Mosher method24. 

A major advance was devised by Pehr Edman (University of Lund, Sweden) that has become the standard method for N-terminal residue analysis. The Edman degradation is based on the chemistry shown in Figure 27.12. A peptide reacts with phenyl isothiocyanate to give a phenylthiocarbamoyl (PTC) derivative, as shown in the first step. This PTC derivative is then treated with an acid in an anhydrous medium (Edman used nitromethane saturated with hydrogen chloride) to cleave the amide bond between the N-terminal amino acid and the remainder of the peptide. No other peptide bonds are cleaved in this step as amide bond hydrolysis requires water. When the PTC derivative is treated with acid in an anhydrous medium, the sulfur atom of the C=S unit acts as... 

Various applications of PITC in analyses of acid hydrolysates of purified proteins and peptides (91) and of hydrolysates of feeds (92) have been described. Bidlingmeyer et al. (93) showed reversed-phase chromatographic analysis of free amino acids and hydrolysates of foods (soybean flour, mozzarella cheese, beer, and soy sauce) with formation of PITC derivatives to be a fast, reproducible method that presented a very good correlation with the results obtained by ion-exchange chromatography. 

The post-column derivatization of amino acids by the ninhydrin technique is a well known method for routine analysis of amino acids [7-9]. The amino acids are usually separated by ion-exchange chromatography and then converted into UV-absorbing derivatives for quantitation. The ninhydrin reaction is often used for TLC detection of amino acids and proteins. 

DNS derivatives of amino acids and peptides are used for the protection of amino groups, separation by TLC and fluorimetric analysis. DNS derivatives can be also used for MS identification and have been employed for the confirmation of a large number of biogenic amines [209]. The molecular ions of these derivatives are usually intense and are often accompanied by an ion at m/e 170 or 171 as the key fragment. BNS derivatives are also useful for MS identification of amines of biological interest [82,83]. 

Structural analysis of N-24 based on amino acid sequence (derived from its cDNA sequence) revealed some very interesting features. The finding that exons 2, 3 and 4 represent the same repeat sequence has led to the suggestion that this repeated domain may have been generated by duplication of an insertion sequence (Katinakis Verma, 1985). The first and last exons are unique and contain hydrophobic domains. While the first hydrophobic domain at the amino-terminal seems to act as a signal sequence, the hydrophobic domain in the last exon may act as a mem-... 

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