High-pressure liquid chromatographic analysis of amino acid phenylthiohydantoins: Comparison with other techniques

High-pressure liquid chromatography, utilizing reverse phase μ Bondapak C₁₈ columns and elution with increasing acetonitrile concentrations, has been used to resolve amino acid phenylthiohydantoins obtained from the automated Edman degradation of proteins. Assignment of identity to residues which are difficult to distinguish or identify conclusively by other conventional techniques is easily achieved by high-pressure liquid chromatographic techniques. The use of high-pressure liquid chromatography, in parallel with gas-liquid and polyamide thin-layer chromatography, allows unequivocal assignments of identity to amino acid phenylthiohydantoins obtained in protein sequencing. Single protein sequence determinations can be extended by 20 to 100% by the use of high-pressure liquid chromatography with rapid, accurate, and quantitative identifications of amino acid phenylthiohydantoins.     

Simple,rapid, and highly efficient separation of amino acid phenylthiohydantoins by reversed-phase high-performance liquid chromatography

A rapid and efficient separation of amino acid phenylthiohydantoins by high-performance liquid chromatography has been accomplished by step-gradient elution with use of a mobile phase of acetate-buffered aqueous acetonitrile and an octadecylsilyl stationary phase. Typical analyses are completed in less than 12 min. Peak elution positions in this procedure are highly reproducible (with about 0.2% variance) and allow unambiguous identification of all residues. A procedure for the optimal positioning phenylthiohydantoin-Arg and -His is given. Molar extinction coefficients at 254 nm, which are particularly useful with common fixed wavelength detectors, are given for 25 amino acid phenylthiohydantoins.     

A rapid and quantitative determination of amino acid phenylthiohydantoins by direct densitometry on thin-layer chromatogram.

Thin-layer chromatograms on silica gel plate of amino acid phenylthiohydantoins were simultaneously used for identification and quantitation. With a scanning, two-wavelength densitometer, linear calibration curves have been obtained for 15 different derivatives, which can be employed for a rapid and simple quantitation of sample spots. A satisfactory application of the method to the determination of amino-terminal residues of bovine α-chymotrypsin is described.     

A method for the selective release and, hence, assay of the carbohydrate moieties of collagen

The carbohydrate residues of collagen were selectively released in high yield by nitrosation of the hydroxylysines of the intact collagen or peptides derived from collagen. The carbohydrate residues (Glc-Gal and Gal) released were separated from the modified protein or peptide by gel chromatography and were assayed by gas-liquid chromatography of their trimethylsilyl derivatives. The results agreed closely with those obtained from methanolysis-gas chromatography or from alkaline hydrolysis followed by amino acid analysis of the hydroxylysyl glycosides. With a more sensitive perbenzoylation-high-performance liquid chromatography method and uv detection at 230 nm, the carbohydrates released by nitrosation of submilligram quantities of collagen or peptide could be assayed accurately.     

A new chemical tool for characterization and partial depolymerization of red algal galactans

Complete acid hydrolysis of red algal galactans in the presence of borane - 4-methylmorpholine complex has been shown to prevent the acid degradation of 3,6-anhydrogalactose derivatives by their reduction to the corresponding 3,6-anhydro-galactitols, whereas all the other monosaccharides are liberated essentially in the non-reduced form; the reductive hydrolysis products may be determined quantitatively using gas-liquid chromatography (GLC). The method is recommended for preliminary characterization of the polysaccharide composition of red algal biomass. Partial acid hydrolysis of galactans in the presence of the same reducing agent gives rise to reduced oligosaccharides having terminal 3,6-anhydrogalactitol residues. Based on this reaction, the attribution of unknown galactans to the agar or carrageenan groups is possible by partial reductive hydrolysis of small samples of algal biomass with subsequent identification of agarobiitol or carrabiitol acetates by GLC. Sulfate groups are substantially retained under partial reductive hydrolysis conditions; the isolation by liquid chromatography and elucidation of structures of reduced sulfated oligosaccharides may be of great value for the structural analysis of complex red algal galactans.     

Transesterification of phospholipids or triglycerides to fatty acid benzyl esters with simultaneous methylation of free fatty acids for gas-liquid chromatographic analysis

A novel method is presented for transesterification of fatty acid esters in phospholipids and triglycerides to benzyl esters while simultaneously recovering free fatty acids as methyl esters. Transesterification is catalyzed by 0.2 M (m-trifluoromethyl phenyl)trimethyl ammonium hydroxide in methylene chloride, 10% (v/v) benzyl alcohol, and 1% (w/v) potassium tert-butoxide, and is complete in 30 min at room temperature. Methyl esters of all common fatty acids separate from the benzyl esters formed from phospholipids. This method has broad utility and is applicable to the formation of esters optimized for detection by absorbance or fluorescence (high performance liquid chromatography), electron capture (gas-liquid chromatography), or negative ion chemical ionization (gas-liquid chromatography-mass spectrometry).     

Isolation and complete amino acid sequence of the mitochondrial ATP synthase epsilon-subunit of the yeast Saccharomyces cerevisiae

All five subunits of yeast mitochondrial F1-ATPase have been isolated by reverse-phase high performance liquid chromatography. This procedure allows micro-preparative purification of all the subunits with 60% recoveries. The complete amino acid sequence of the epsilon-subunit has been established. This has been achieved by the sequence analysis of subnanomole amounts of the intact molecule and that of peptides derived by enzymatic digestion with endoproteinase Arg-C and by chemical cleavage with hydroxylamine. Yeast ATP synthase epsilon-subunit is composed of 61 residues with a calculated molecular mass of 6612 Da. This polypeptide is rather basic since it contains 7 basic residues and 3 acidic residues. This study shows a slight similarity with the bovine epsilon-subunit ATP synthase since there are 16 identical residues.     

The purification and chemical characterisation of the alginate present in extracellular material produced by mucoid strains of Pseudomonas aeruginosa

A rapid ion-exchange method has been used to purify the alginate from the extracellular material of mucoid strains of Pseudomonas aeruginosa isolated from the lungs of cystic fibrosis patients. The structure has been investigated by chemical analysis, infrared spectroscopy, paper chromatography, and gas-liquid chromatography. The alginates contain mainly random or poly(D-mannuronic acid) block structures, and are highly acetylated. The relative viscosity is not correlated with the ratio of D-mannuronic acid to L-guluronic acid residues, or the degree of acetylation. The chemical/physical properties of the alginate from P. aeruginosa are considered in the context of the growth of the organism in the lung.     

Direct microsequence analysis of polypeptides using an improved sequenator, a nonprotein carrier (polybrene), and high pressure liquid chromatography

We have combined the use of a nonprotein carrier (Polybrene), high pressure liquid chromatography, and modifications in Edman chemistry with the improvements of a commercial spinning cup sequenator suggested by Wittmann-Liebold [Wittmann-Liebold, B. (1973) Hoppe-Seyler's Z. Physiol. Chem. 354, 1415] to analyze amino acid phenylthiohydantoins obtained from automated Edman degradation of microquantities of polypeptide directly without the use of radiolabel. This approach has allowed us to determine the sequence of the N-terminal 47 residues of sperm whale myoglobin starting with 200 pmol of protein, 77 residues of an antibody light chain with 5 nmole of protein, and 54 residues of an antibody heavy chain with 8 nmol of protein. In addition, we completely sequenced a hydrophobic 14-residue peptide at the 1.5-nmol level. Our technique of direct analysis for microsamples is capable of providing routine, extende N-terminal sequence analysis for nanomole and subnanomole levels of polypeptides and protines, and it also is applicable to analysis of more classical sample quantities.     

Elution-band relaxation method. A method to analyze isomerization kinetics by HPLC and application to protein denaturation-renaturation

We present a novel method, the 'elution-band relaxation method', to analyze quantitatively reversible isomerization kinetics by elution chromatography, taking advantage of the high resolution and speed of high-performance liquid chromatography (HPLC). The kinetic information is obtained by measuring the first temporal moments of chromatograms of molecules undergoing isomerization and analyzing their dependence on the column length or flow rate. The major advantage of this method is that it is applicable to reactions as fast as the time of elution in HPLC, a speed which has not been attained previously in analysis of isomerization reactions based on the chromatographic property of molecules. We describe the method and report an experimental application to the denaturation-renaturation kinetics of bovine pancreatic ribonuclease A as an example.     

The separation of enantiomeric sugars by chromatographic methods

This paper has reviewed the number of chromatographic methods by which one may determine the absolute configuration of sugars. Both indirect methods (converting the enantiomeric pair into diastereomers) and direct methods (using chiral stationary phases) have been discussed. Resolving reagents for the indirect methods include chiral hydroxy compounds, chiral amines, and chiral thiols; with subsequent separation of the diastereomers either by gas-liquid chromatography or by high pressure liquid chromatography. Direct methods discussed have exclusively utilized chiral substitution of organopolysiloxane phases for the separation of enantiomeric sugars as volatile derivatives by gas-liquid chromatography.     

A novel high-performance anion-exchange chromatographic method for the analysis of carrageenans and agars containing 3,6-anhydrogalactose

A novel method has been developed to determine the sugar composition of 3,6-anhydrogalactose-containing polysaccharides, such as carrageenan and agar. The method is based on reductive hydrolysis with a methylmorpholine-borane complex in the presence of acid and subsequent high-performance anion-exchange chromatography analysis of the alditols without any derivatization. The method was validated by 13C NMR analysis of six carrageenans and three agars and by a previously used method based on derivatization to alditol acetates and gas-liquid chromatography analysis. The new method was found to be superior to the gas-liquid chromatography method as the analysis time was less than half. Also it was found to be more accurate and reproducible and no derivatization was required. The analysis of the six different carrageenan samples revealed that homogeneous mu- and nu-carrageenan, theoretically without 3,6-anhydrogalactose residues, cannot be isolated from red seaweeds. Consequently, the question arose if mu- and nu-carrageenans at all are present in seaweeds and if the current hypotheses regarding biosynthesis of carrageenans in the seaweeds are correct. The data demonstrated that carrageenans are highly complex natural polysaccharides, which are more irregular than assumed hitherto. The new analytical technique will permit elucidation of the detailed structure of seaweed polysaccharides and determination of their structure-property relationships.     

Reverse phase high performance liquid chromatography of Escherichia coli ribosomal proteins: standardization of 70 S, 50 S, and 30 S protein chromatograms

We recently described the use of reverse phase high performance liquid chromatography for the separation of the proteins of the 30 S subunit of Escherichia coli ribosomes (Kerlavage, A. R., Kahan, L., and Cooperman, B. S. (1982) Anal. Biochem. 123, 342-348). In the present studies we report improvements in the technique and its extension to the separation of the proteins of the 50 S subunit and of 70 S ribosomes. Using an octadecasilyl silica column and a trifluoroacetic acid/acetonitrile solvent system, the 21 proteins of the 30 S subunit have been resolved into 17 peaks, the 33 proteins of the 50 S subunit into 22 peaks, and the 53 proteins of the 70 S ribosome into 31 peaks. The proteins present in each peak have been identified by polyacrylamide gel electrophoresis, by comparison with previously standardized chromatograms, and by calibration with authentic samples of purified proteins. All of the known ribosomal proteins have been identified on the chromatograms with the exception of L31 and its variant, L31'. Three protein peaks, not corresponding to known ribosomal proteins, have been observed in preparations from the total protein from 50 S subunits and 70 S ribosomes, but the significance of these peaks is unclear. The reverse phase high performance liquid chromatography technique has the potential for purifying all ribosomal proteins, as demonstrated by the increase in resolution we obtain when a peak isolated under standard gradient conditions and containing several proteins is reapplied to the column and eluted with a shallower gradient. Its utility in preparing proteins for functional studies is demonstrated by a reconstitution of active 30 S particles using 30 S proteins prepared by reverse phase high performance liquid chromatography.     

Pyrolysis gas-liquid chromatography of the genus Bacillus: effect of growth media on pyrochromatogram reproducibility.

Pyrolysis gas-liquid chromatography was performed on dried Bacillus microorganisms to evaluate the effects of growth media. Six cultures of Bacillus and six lot numbers of Trypticase soy agar (BBL) were used to test the hypothesis that a microorganism grown on various lot numbers of the same chromatogram. Also tested was the effect of three different media on chromatogram reproduction using the same six cultures. Results show little or no differences observed between the chromatograms of the individual Bacillus spp. grown on the six lot numbers of Trypticase soy agar. When chromatograms of the three different media were compared, several differences were observed, particularly in the areas most characteristic of individual species. Pryolysis gas-liquid chromatography can be a useful tool for the characterization or identification of the genus Bacillus if the chromatographic and cultural conditions are maintained.     

Highly sensitive quantitative analysis of nicotianamine using LC/ESI-TOF-MS with an internal standard

A highly sensitive quantitative method for analyzing nicotianamine (NA) by liquid chromatography/electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOF-MS) is reported. Fluorenylmethoxycarbonylation of nicotianamine reduced its polarity and enabled its retention in a reversed-phase column. The adoption of N(epsilon)-nicotyllysine (NL) as an internal standard ensured reliable quantification by giving a linear calibration curve drawn between the NA/NL molar ratios of standard solutions injected and the NA/NL area ratios in mass chromatograms. The high sensitivity of this analytical method allowed us to measure the amount of NA. This analytical method has applications to all research concerning NA.     

Analysis of kavalactones from Piper methysticum (kava-kava)

The chemical analysis and quality control of both Piper methysticum G. Forster (kava-kava) and extracts obtained by aqueous acetone or aqueous methanol as well as supercritical fluid extraction are reviewed. In the last two decades various procedures concerning the separation and detection of kavalactones have been routinely carried out by gas chromatography (without previous derivatization of kavalactones) and high performance liquid chromatography but most of them are not validated or only partially validated. Recently, analyses by supercritical fluid chromatography and micellar electrokinetic chromatography have also been reported. Both gas chromatography and high performance liquid chromatography can be used for the analysis of kavalactones with some advantages and disadvantages for each method. Using gas chromatography analysis, methysticin and yangonin, which are two of the major components, are generally not separated. In addition, the high temperature of the injection port caused the decomposition of methysticin. Concerning high performance liquid chromatography analyses, the reversed-phase is generally better because highly reproducible with a very low detection limit for all compounds even if the quantitative analysis of the kavalactones by liquid chromatography needs to be carried out in the absence of light to prevent the cis/trans isomerisation of yangonin.     

Relaxed specificity of endoproteinase Asp-N: this enzyme cleaves at peptide bonds N-terminal to glutamate as well as aspartate and cysteic acid residues

Asp-N, an endoproteinase specific for cleavage of protein or polypeptide bonds N-terminal to aspartate or cysteic acid residues, has been shown to possess a similar affinity for certain glutamate residues. Of 18 glutamate residues present in 2 cyanogen bromide fragments of apolipoprotein A-I, 5 residues were cleaved at rates comparable to that of cleavage at the 12 internal aspartate residues present in these polypeptides (all of which were cleaved). Cleavage of these 5 glutamate residues was obtained under standard enzyme digestion conditions, and the identities of all peptides obtained by Asp-N digestion were determined by amino acid sequencing of peaks obtained from reversed-phase high performance liquid chromatography.     

Resolution of some glycopeptides of hen ovalbumin by reverse-phase high-pressure liquid chromatography

Reverse-phase high-pressure liquid chromatography has been shown to be useful in fractionation of oligosaccharides containing N-acetyl amino sugars on the basis of stereochemical differences. Data in this paper show this same stereochemical selectivity can be obtained for glycopeptides. Using dilute aqueous phosphate for elution, three major high-mannose glycopeptides from ovalbumin can be separated on the analytical scale in a few minutes and the same method can also be used for preparation of the glycopeptides on the milligram scale. High-field proton NMR spectroscopy is used to identify two of the compounds as the mannose-5 and -6 glycopeptides (E3 and D3) and the third as the mannose-6 glycopeptide substituted by two N-acetyl glucosamine (GlcNAc) residues (C3B). The NMR spectra and analytical chromatograms of the glycopeptides show high purity and freedom from contaminants previously identified in ovalbumin glycopeptides.     

Ultramicro determination of plasma testosterone by electron-capture detection of testosterone diheptafluorobutyrate

1. A new highly sensitive and accurate ultramicro method for the estimation of testosterone in human peripheral plasma is described. The method uses paper-and thin-layer-chromatographic separation of plasma testosterone, which is determined as testosterone diheptafluorobutyrate by electron-capture detection after gas-liquid chromatography. 2. The average difference between duplicates is +/-2% (range 1-5%) with as little as 2.5ml. of human male peripheral plasma. With 10ml. of plasma the method is sensitive enough for the accurate determination of testosterone in human female plasma. The high order of accuracy is achieved by the use of a radioactive label and an internal standard for gas chromatography, and by obtaining several gas chromatograms from the same plasma sample. 3. As little as 40mumug. of peripheral plasma testosterone can be detected. The method is 20 times as sensitive as electron-capture techniques with the monochloroacetate derivative. 4. The method is simpler and quicker than double-isotope-derivative methods, and slightly more sensitive. The advantages of the method, which is specific for testosterone, are its high sensitivity and accuracy, which are achieved with relative convenience.     

A method for the estimation of urinary testosterone

1. A method has been developed for the estimation of testosterone in human urine by using acid hydrolysis followed by a quantitative form of a modified Girard reaction that separates a ;conjugated-ketone' fraction from a urine extract; this is followed by column chromatography on alumina and paper chromatography. 2. Comparison of methods of estimation of testosterone in the final fraction shows that estimation by gas-liquid chromatography is more reproducible than by colorimetric methods applied to the same eluates from the paper chromatogram. 3. The mean recovery of testosterone by gas-liquid chromatography is 79.5%, and this method appears to be specific for testosterone. 4. The procedure is relatively rapid. Six determinations can be performed by one worker in 2 days. 5. Results of determinations on human urine are briefly presented. In general, they are similar to earlier estimates, but the maximal values are lower.