Amino acid by ion-exchange chromatography

These are the definitions of the two characteristic dissociation constants normally expressed in terms of p K. When three dissociating groups are present in a molecule there are three piC values, ie, pfC, P 3- knowledge of these piC values is important in the separation or isolation of each amino acid by ion-exchange chromatography. 

JM Manning, S Moore. Determination of d- and L-amino acids by ion-exchange chromatography as l-d and l-l- dipeptides. J Biol Chern 243, 5591, 1968. 

Saunders. S.J. et al. "Modeling the Separation of Amino Acids by Ion-Exchange Chromatography," Chem. F.ng. Progress. 47 (August 1988). 

The number of each type of amino acid in a protein can be determined by acid hydrolysis and separation of the individual amino acids by ion exchange chromatography The amino acids are detected by colorimetric reaction with, for example, ninhydrin or fluorescamine. 

Fig. 3-4 Separation of amino acids by ion-exchange chromatography. The areas under the peaks are proportional to the amounts of amino acids in the solution.

Figure 21.22. Separation of amino acids by ion-exchange chromatography. Resin Durrum DC-IA, a sulfonatedpolystyrene-divinylbenzene cation exchanger of dp = S pm. Ten nanomole calibration mixture. Flow rate 70 mljhr. From James R. Benson, Durrum Resin Report No. 5, April, 1973, Durrum Chemical Corp., by permission of Durrum Chemical Corp.

Analysis of a mixture of amino acids by ion-exchange chromatography using Amberlite IR-120, a sulfonated polystyrene resin.The resin contains phenyl-S03 Na groups.The amino acid mixture is applied to the column at low pH (3.25), under which conditions the acidic amino acids (Asp, Qlu) are weakly bound to the resin and the basic amino acids (Lys, His, Arg) are tightly bound. Sodium citrate buffers of two different concentrations and three different values of pH are used to elute the amino acids from the column. Cysteine is determined as cystine, Cys-S-S-Cys, the disulfide of cysteine. 

Much of the remarkable progress in protein chemistry over the past years has been due to the development of accurate and convenient methods for the qualitative and quantitative analysis of amino acids. The most common procedure for amino acid analysis of a protein involves acid hydrolysis in the absence of oxygen, resolution of the amino acids by ion-exchange chromatography, and colorimetric estimation with ninhydrin (369). 

Amino Acids. Kemp and Mudrochova (1973) determined amino acids and amino sugars by ion-exchange chromatography in 6N HCl hydrolysates of humic and fulvic acids from Lake Ontario sediments. They obtained total amino acids of 21.5% for humic acid and 12.6% for fulvic acid. Total amino sugars accounted for only 1.9 and 1.3% for humic acid and fulvic acid, respectively. They found the amino acid distribution in the humic acid resembled that of zooplankton and suspended sediment samples, with the exception of glycine which was higher in the sediments. This lends support for the assumed autochthonous nature of lake sediment organic matter. On the other hand, basic amino acid concentrations were low in the fulvic acid and its amino acid distribution resembled the combined form in the interstitial waters. 

Another synthesis of (2R,2 71)-(+)-Z/zreo-methyl-phenidate hydrochloride (1) using an enantiomerically pure starting material, u-pipecolic acid (15), was reported by Perel et al. (Scheme Enantiomerically pure D-pipecolic acid (15) was obtained in 57% yield by recrystallization of diastereomeric tartrate salt, followed by the separation of the desired amino acid from tartaric acid by ion-exchange chromatography. D-Pipecolic acid (15) was protected with a BOC group to afford M-BOC-n-pipecoUc acid (16) in 97% yield. The key amino ketone (18 ... 

The most established method for enzymatic L-amino acid synthesis is the resolution of racemates of N-acetylamino acids by acylase I from AspergiUus oryzae fungus. The N-acetyl-L-amino acid is cleaved to yield L-amino acid whereas the N-acetyl-D-amino acid does not react. After separation of the L-amino acid through ion exchange chromatography or crystallization, the remaining N-acetyl-D-amino acid can be... 

Houpert, Y., Tarallo, P., and Siest, G., Amino acid analysis by ion-exchange chromatography using a lithium elution gradient. Influence of methanol concentration and sample pH, /. Chromatogr., 115, 33, 1975. 

Briddon, A., Total plasma homocysteine as part of the routine aminogram by ion-exchange chromatography, Amino Acids, 15, 235, 1998. 

The peptide/polypeptide product is usually hydrolysed by incubation with 6 mol l-1 HC1 at elevated temperatures (110 °C), under vacuum, for extended periods (12-24 h). The constituent amino acids are separated from each other by ion-exchange chromatography and identified by comparison with standard amino acid preparations. Reaction with ninhydrin allows subsequent quantification of each amino acid present. 

Essentially the same amino acids, and nearly equal quantities of D and L enantiomers, were detected in the Murray meteorite, another type II carbonaceous chondrite [6]. Recent expeditions to Antarctica have returned with a large number of meteorites, many of which are carbonaceous chondrites. These may have been protected from terrestrial contamination by the pristine Antarctic ice. Careful analysis of two of these, the Yamato (74662) and the Allan Hills (77306), both type II carbonaceous chondrites, by ion exchange chromatography, gas chromatography, and GC/MS, have detected a wide variety of both protein and non-protein amino acids in approximately equal D and L abundances [9,10]. Fifteen amino acids were detected in the Yamato meteorite and twenty in the Allan Hills, the most abundant being glycine and alanine. The amino acid content of the Yamato meteorite is comparable with that of the Murchison and Murray, but the Allan Hills contains 1/5 to 1/10 that quantity. Unlike earlier meteorites from other locations, the quantities of amino acids in the exterior and interior portions of the Yamato and Allan Hills meteorites are almost identical [9,10]. Thus, these samples may have been preserved without contamination since their fall in the blue ice of Antarctica, which js 250,000 years old in the region of collection. 

Ion exchange chromatography at pH 5.25 of the aqueous fractions yielded six peaks, I - VI (fig. 1). Peak V contained a mixture of amino acids (TLC with n-propanol/ammonia/water = 8 1 11 by vol.) (table 1). Therefore, the pooled fractions of V were separated at pH 3.5 (fig. 2). Three peaks were observed, the first probably representing ammonia formed from azide. The second peak (V-1) still displayed a minor impurity on TLC, whereas the third peak (V-2) appeared as a single spot. Peak V-1 could not be separated further by ion exchange chromatography at pH 7.0 (peak V-1-1). 

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