The complete gas-liquid chromatographic separation of the twenty protein amino acids

Morphological, Physiological and Genetic Characteristics of Populations of the Main Plague Host Rhombomys opimus Licht., 1823 in the Central Asian Desert Natural Focus of Plague

Revealed by morphological characters, physiological status, and genetic diversity of populations of the main plague host Rhombomys opimus Licht., 1823 in Central Asia desert natural focus is described.Differences in the skull parameters of R. opimus from different populations were revealed. It’s shown that gerbils from Moyunkum are separate autonomous populations group. Samples from Moyunkum and Mangyshlak differed from other samples. In Balkhash-Alakol depression found two regional complexes: Pre-Balkhash and Dzungarian.Study results of free amino acids level in R. opimus blood serum obtained by gas-liquid chromatography of blood sera from animals captured in different zones of Central Asian focus gave statistically significant differences. To determine genetic variability in ecological and geographical isolation of R. opimus populations the DNA was genotyped.DNA samples analysis combined the studied gerbil from the desert focus into four clusters with eighteen haplotypes. R. opimus sequence analysis taking into account data from territories of Iran, Kazakhstan and China, clustered into three large clusters. First cluster combined the sequences of Kazakhstan and China samples, while great gerbil captured in Kazakhstan is located in a separate treasure. Second and third clusters include sequences of a great gerbil captured in Iran.

The contribution of gas chromatography to the resynthesis of the post-Byzantine artist’s technique

Gas chromatographic analysis of ethyl chloroformate derivatives of samples taken from the paint layers of post-Byzantine panel paintings permitted the successful characterisation of the different binding media used in them. This paper describes an analytical study of various post-Byzantine binding media such as egg yolk and egg/oil emulsion, using gas chromatography. The characterisation of these icons' binding media is an important task, as it contributes to our understanding of and the reconstruction of the post-Byzantine artists' palette. It also enables us to investigate the validity of our assumptions about the influences of Venetian style on Greek icon painting techniques from the sixteenth to the early nineteenth century, which up to now have been based on information in artists' handbooks. The methodology involves two experimental steps: (1) hydrolysis of the proteins and triglycerides in the binding media to obtain free amino acids and fatty acids, and (2) the formation of ethyl chloroformate derivatives via derivatization with ethyl chloroformate (ECF). This methodology is of considerable interest, since it permits the identifcation of the nature of the proteinaceous binders used in these works through the simultaneous derivatization and determination of amino acids and fatty acids. Advantages of this methodology include the small quantity of sample required and the minimum preparation time involved. The proteinaceous media can be determined based on the ratios of seven stable amino acids, while the type of emulsions and drying oils used can be determined from the fatty acid ratio.

Protein quality and iron bioavailability of mechanically and hand-deboned turkey meat fed to rats

The protein quality and iron bioavailability of mechanically deboned turkey meat (MDT) and hand-deboned turkey meat (HDT) were determined in rats. The protein, fat, and moisture levels in MDT were similar to those found in HDT. The MDT, however, contained more ash, calcium, and iron than the HDT. The MDT and HDT had similar amino-acid patterns; methionine and cystine were the limiting amino acids for both products. The amino-acid scores were .97 and .98 for MDT and HDT, respectively. The protein efficiency ratio and biological value as well as the values for net protein utilization and nitrogen efficiency for growth for MDT were similar to those for HDT and reference casein (P greater than .05). The hemoglobin-regeneration efficiency values were 40, 39, and 55%, respectively, for MDT, HDT, and FeSO4 (least significant difference = 12%). The MDT contained more bioavailable iron (7.6 mg of iron per kg of meat or 4.1 mg of iron per 1,000 kcal) than the HDT (4.2 mg/kg or 2.4 mg/1,000 kcal). Mechanically deboning turkey meat did not affect its protein quality, but increased the amount of bioavailable iron.

Gas chromatographic analysis of histidine: effect on other amino acids present

Earlier proposals aimed at increasing the detector responses of histidine in gas chromatographic analysis have been compared and contrasted with regard to their effect on the other amino acids present. Twenty-one amino acids have been measured in the form of their N,O,(S)-trifluoroacetyl (TFA) isobutyl esters. Detector responses of the amino acid N,O,(S)-TFA isobutyl esters of dichloromethane solutions alone and mixed with acetic anhydride were recorded and compared with those of other TFA esters. Reproducibility data for chosen representative amino acid N,O,(S)-TFA isobutyl esters are presented.

Gas chromatography of amino acids in urine and haemofiltrate

Capillary gas chromatography of amino acid derivatives obtained from biological material shows a large number of previously unknown constituents. The profiles of amino acids obtained from urine of healthy individuals and haemofiltrate of uraemic patients indicate that haemofiltration removes some amino acids to a considerably higher extent from uraemic patients than the kidney does from healthy persons. For instance, if haemofiltration is required three times a week, an approximately ten-fold amount of the essential amino acid methionine and a forty-fold amount of the essential amino acid leucine is lost compared to their excretion in urine by a healthy individual over the same period.

Gas-liquid chromatographic determination of N(O,S)-trifluoroacetyl n-propyl esters of protein and non-protein amino acids

Chromatographic conditions for the determination of protein and non-protein amino acids as their N(O,S)-trifluoroacetyl n-propyl esters are given which allow the separation of about 30 amino acids within 19 min using nitrogen or within 17 min using helium as the carrier gas. Retention times and responses are given for 42 amino acids or related compounds. Only few of them elute together when using a 2 m x 2 mm I.D. glass column filled with 0.65% ethylene glycol adipate on Chromosorb W AW (80-100 mesh). The acylation of the n-propyl esters was investigated with respect to optimal reaction conditions and was found to be best performed at 150 degrees C for 5 min.

Practical gas-liquid chromatographic method for the determination of amino acids in human serum

Application of the gas--liquid chromatographic method previously reported by us was made to the analysis of the 22 amino acids including asparagine and glutamine in serum. The method permitted that aqueous serum samples obtained after deproteinization with perchloric acid were directly subjected to derivatization without any further clean-up procedure such as ion-exchange chromatography. The N-ethyloxycarbonyl methyl esters, which were prepared in the same manner as the N-isobutyloxycarbonyl methyl esters, were introduced for the determination of leucine, isoleucine, arginine and tyrosine. Both derivatives were prepared by two-step procedures involving alkyloxycarbonylation in aqueous media and esterification with diazomethane, and simultaneously analyzed by using the dual set of columns with the same thermal conditions. The advantages of this method are that the sample pretreatment and derivatization are very simple and rapid, and that both asparagine and glutamine along with other amino acids in serum can be determined.

Determination of urinary amino acids by means of glass capillary gas-liquid chromatography with alkali-flame ionisation detection and flame ionisation detection

The determination of amino acids as their N(O)-heptafluorobutyryl-isobutyl ester derivatives by glass capillary gas--liquid chromatography has been studied. Separations of amino acids obtained from insulin hydrolysate and human urine analysed with a flame ionisation detector, an alkali-flame ionisation detector and an electron-capture detector are shown. The quantitative results of urinary amino acids of one deep-sea diver are presented.

Regulation of pool sizes and turnover rates of amino acids in humans: 15N-glycine and 15N-alanine single-dose experiments using gas chromatography-mass spectrometry analysis

Gas chromatography--mass spectrometry (GCMS) of plasma amino acid derivatives has been used to determine directly the 15N-enrichment of plasma glycine and alanine in ten volunteers at various metabolic states. Isotope-enrichment time-decay curves of plasma glycine and alanine, following a single intravenous dose of 15N-glycine or 15N-L alanine were obtained and provide an estimate of the extracellular compartment. Relatively narrow ranges were obtained for the glycine pool (7.7--11.8 micromole/100 g body wt), rate constants of transport (3.7--4.2 hr-1) and flux (28--43 micromole hr-1/100 g body wt) in the postabsorptive statcine pool (7.7--11.8 mumole/100 g body wt), rate constants of transport (3.7--4.2 hr-1) and flux (28--43 mumole hr-1/100 g body wt) in the postabsorptive state. In postprandial humans, pool sizes showed only a modest variation whereas the rate constants of transport of glycine and alanine were significantly lower. The plasma 15N-glycine and 15N-alanine isotope-enrichment time-decay curves over the first hour following a single i.v. dose of 15-amino acid represent mostly the hepatic uptake of glycine and alanine from the extracellular pool. The results presented in this study establish the stable isotope GCMS method as a more accurate, more convenient, and safe alternative to the use of radioactive labeled amino acids in studies of amino acid metabolism in human subjects.

Determination of erythrocyte amino acids by gas chromatography

Erythrocyte amino acid levels were determined, by gas chromatography, in a group of 34 normal human adults. No significant sex or age correlations were noted. A method for the quantitative gas chromatographic analysis of free amino acids in erythrocytes is described. Following hemolysis and deproteinization the amino acids were isolated on a cation-exchange resin. Glutathione was removed from the amino acid mixture by adsorption on an anion-exchange resin. Following conversion to their N-acetyl-n-propyl esters, 19 amino acids were separated and quantitated by gas chromatography on a single column in 18 min. Typical reproducibility data indicate that a coefficient of variation of 2-5% is attainable.

Plasma amino acid turnover rates and pools in rabbits: in vivo studies using stable isotopes

Gas chromatography--mass spectrometry of plasma amino acids has been used to determine the 15N enrichments of plasma glycine and alanine in rabbits in different metabolic states. Isotope-enrichment time-decay curves of plasma amino acids were linear over the course of the measurements after intravenous administration of a single dose of 15N-amino acid. Glycine and alanine pools and turnover rate constants were estimated from decay data. The effects of diurnal variation and fasting on glycine and alanine pool sizes, turnover rates, and flux in rabbits were studied to provide information on the effect of metabolic stress on amino acid kinetics in the whole body. The observations suggests that the transport of systemic glycine or alanine into the hepatocyte is under the control of a regulatory mechanism that compensates for decrease in the extracellular levels of the amino acids by enhancing the activity of the transport system. The volumes of the glycine and alanine pools were found to correspond to the extracellular space of rabbits, and the glycine and alanine pools can be identified as extracellular. We conclude that the plasma glycine and alanine 15N isotope-enrichment time-decay curves over the 1st h after a single intravenous dose of the amino acid represent mainly the hepatic uptake of glycine and alanine from the extracellular pool.

Protein amino acid analysis by an isotope ratio gas chromatography mass spectrometry computer technique

A method for quantitative analysis of protein amino acids by a gas chromatography mass spectrometry computer system is described. Amino acids were analysed as their N-trifluoroacetyl n-butyl ester derivatives. Isotope ratio determination was used as the quantitating technique via multiple internal standards. The exact composition of a deuterated amino acid mixture was determined against a standard amino acid calibration mixture and in turn the protein amino acid composition was determined against the deuterated amino acid mixture. The amount of protein taken for analysis was 100 micrograms and the procedure, excluding hydrolysis, could be performed with 2 1/2 hours. The introduction of the internal standards prior to protein hydrolysis provides a method with good precision (mean coefficient of variation less than 5%). The method, tested on insulin, gave results which agreed well with the known composition of the protein and with simultaneous analysis on ion exchangers.

Fluorescamine use in high-performance liquid chromatographic determination of aminocaproic acid in serum

A sensitive and specific high-performance liquid chromatographic determination of aminocaproic acid in serum is described. omega-Aminocaprylic acid is used as an internal standard. To 10 microliter of serum, 10 microliter of the internal standard solution and 50 microliter of ethanol are added. After centrifugation, a portion of the supernate is evaporated. The residue is dissolved in 750 microliter of 50 mM dibasic sodium phosphate, and then 250 microliter of fluorescamine in acetonitrile (35 mg/100 ml) is added. The reaction mixture is chromatographed using a column of octadecylsilane bonded to silica and 44% acetonitrile in 0.5 mM phosphoric acid as the eluent. Quantitation is achieved by monitoring either the absorbance of the effluent at 405 nm or the fluorescence of the compounds with a fluorometer equipped with a flowcell. The method is reproducible, simple, and fast and has a precision of 4.4%.

Determination of carbocysteine from human plasma

A fast and accurate GLC procedure for determining carbocysteine, using a sulfur photometric detector, is described. Interferences from nonsulfur constituents are eliminated. The method is linear from 2 to 15 micrograms. Results from the application of this method to a bioavailability study in humans are given.

The determination of amino acid pool sizes and turnover rates by gas chromatographic mass spectrometric analysis of stable isotope enrichment

Gas chromatography mass spectrometry has been used to determine the 15N enrichment of plasma glycine of rabbits at various times following the intravenous administration of 15N-glycine. These data were used to prepare isotope enrichment time decay curves for eleven individual animals. The slopes and intercepts of least squares lines that describe the decay curves were considerably more accurately than those reported in similar studies employing radioactive tracers. Individual glycine pool sizes (13.8-37.4 micronmoles per 100 g body wt), turnovers rates (2.66-3.36 pools h-1) and flux (50.4-99.7 micronmoles h-1 per 100 g body wt) were estimated from these parameters in a group of animals and compared with the literature values. These results demonstrate that low risk non-radioactive stable isotopes can be substituted for radioactive tracers in studies of human amino acid metabolism, with considerable saving in time and without loss in accuracy, when gas chromatography mass spectrometry is used to determine plasma amino acid and stable isotope enrichment.

Solvent-generated ion-exchange systems with anionic surfactants for rapid separations of amino acids

The retention behaviour of amino acids in phase systems consisting of a hydrophobic solid support as the stationary phase and water-organic solvent mixtures containing a small amount of an anionic detergent as the mobile phase was investigated. Such phase systems are found to behave like conventional ion-exchange systems. The degree and order of retention of amino acids can be influenced by changing the temperature, the nature of the hydrophobic support, the pH and the nature and concentration of the anionic detergent, organic constituent and counter ion in the eluent. In many instances this solvent-generated (dynamic) ion-exchange chromatography shows a greater selectivity than conventional ion-exchange systems towards amino acids. The results obtained so far indicate that a complete separation of the 19 protein amino acids by applying solvent gradients or/and multi-column system is possible within 30 min.

Quantitative analysis of protein and non-protein amino acids by gas-liquid chromatography

The quantitative analysis of protein and non-protein amino acids by gas-liquid chromatography is described. The amino acids are determined as their n-butyl N-trifluoroacetyl esters on an OV-17 (methylphenyl silicone polymer) column. The relative molar responses of 16 protein and 30 non-protein amino acids are reported.

Gas chromatography-mass spectrometry of trimethylsilyl derivatives of omega-amino acids

The silylation of C4-C11 omega-amino acids and their hydrochlorides was carried out with N,O-bis(trimethylsilyl)acetamide. Di-TMS and tri-TMS derivatives were formed in the silylation of the hydrochlorides. The formation of the two derivatives is dependent on the reaction conditions, and the conditions under which only derivative arises reproducibly, are reported. This finding may be utilized in the quantitative analysis of amino acids.

An improved technique for the gas-liquid chromatographic separation of the N-trifluoroacetyl n-butyl derivatives of amino acids

A complete separation of the twenty protein amino acids and two internal standards in 35 min has been made possible by analyzing their N-trifluoroacetyl n-butyl (TAB) derivatives simultaneously on an ethylene glycol adipate (EGA) column and on an OV-17 column using the same temperature programme. The detector signal from the EGA column is recorded up to the point just after the elution of TAB-aspartic acid; thereafter, the signal from the effluent of the OV-17 column is recorded. The TAB derivative of norleucine is poorly resolved from TAB-leucine and TAB-proline. Therefore, alpha-aminocaprylic acid has been used as the internal standard instead of noreleucine. TAB-alpha-aminocaprylic acid appears as a separate peak between TAB-serine and TAB-cysteine.

Fluorescence and the structure of proteins. XXII. Fluorescence of aminotyrosyl residues formed in ribonuclease A

1. Tyrosyl residues on ribonuclease A were nitrated with tetranitromethane and then reduced to aminotyrosyl residues. By variation of reaction conditions and degree of exposure of tyrosyl residues it was possible to convert from 1 to all 6 tyrosyl to aminotyrosyl residues. 2. At the lower levels of 1-3 aminated tyrosyl residues/molecule the change in conformation seemed minor and 70% of the enzymatic activity was retained. When the three buried tyrosyl residues or all six residues were aminated only 5% of the enzymatic activity was retained. 3. Titration data, susceptibility to urea denaturation, and fluorescence characteristics indicated that some of the aminotyrosyl residues were buried in the interior and others were exposed on the surface of the protein. On the basis of the activation/emission wavelengths it was possible to distinguish buried (288/320 nm) and exposed (288/365-395 nm) aminotyrosyl residues as well as exposed tyrosyl residues (275-305 nm). 4. The modification of specific tyrosyl residues on a protein to aminotyrosyl residues appears to have some promise for observation of changes in environment of the residues that accompany various conformation changes by monitoring the fluorescence.

Applications of gas-liquid chromatography in protein chemistry. Determination of C-terminal sequences on nanomolar amounts of proteins

A method for the determination of C-terminal amino acids and C-terminal amino acid sequences in nanomolar amounts of proteins is described, based on carboxypeptidase A digestion of the protein, followed by removal of the partially digested protein and quantitative gas-liquid chromatographic determination of the amino acids released after known time intervals. Sequences deduced from the kinetics of release of specific amino acids are compared with the known C-terminal sequences of well-characterized proteins.