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[Comparison of peptide maps and functional properties of monooxygenases induced by 3-methylcholanthrene and beta-naphthoflavone].

A comparative study revealed a similarity of catalytic, spectral, electrophoretic and immunochemical properties of microsomal cytochromes P-448 (Mr = 56,000) synthesized de novo in 3-methylcholanthrene- and beta-naphthoflavone-treated rats. The identity of peptide maps of microsomal and isolated cytochromes P-448 confirms the validity of the limited proteolysis method for identification of the homogeneity of microsomal hemoproteins and for a comparison of their structures. The data obtained provide a way for evaluation of similarity and differences in the structure and enzymatic activity of various monooxygenase forms without their preliminary isolation from the microsomal membrane.

Animals↗

Purification and enzymatic peptide mapping of protein synthesis elongation factor-2 from mink and chicken livers.

This investigation has shown it it possible to purify elongation factor-2 from livers of two rather distinct animal species, minks and chicken, to high homogeneity by employing the same purification procedure. It is also shown that making peptide maps of the factor by the use of Staphylococcus aureus Endoprotease Glu-C gives the same pattern. Combined, these two experimental approaches show that the evolution has conserved this elongation factor in two species with a rather different physiology and choice of feeding substances. It is also shown that using mink or chicken livers as staring material for purification of eEF-2 is both technically and economically sound when obtaining large amounts of highly purified eEF-2 is the ultimate goal.

Animals↗

Single active-site histidine in D-xylose isomerase from Streptomyces violaceoruber. Identification by chemical derivatization and peptide mapping.

Group-specific chemical modifications of D-xylose isomerase from Streptomyces violaceruber indicated that complete loss of activity is fully correlated with the acylation of a single histidine. Active-site protection, by the ligand combination of xylitol plus Mg2+, completely blocked diethyl pyrocarbonate derivatization of this particular residue [Vangrysperre, Callens, Kersters-Hilderson & De Bruyne (1988) Biochem. J. 250, 153-160]. Differential peptide mapping between D-xylose isomerase, which has previously been treated with diethyl pyrocarbonate in the presence or absence of xylitol plus Mg2+, allowed specific isolation and sequencing of a peptide containing this active-site histidine. For this purpose we used two essentially new techniques: first, a highly reproducible peptide cleavage protocol for protease-resistant, carbethoxylated proteins with guanidinium hydrochloride as denaturing agent and subtilisin for proteolysis; and second, reverse-phase liquid chromatography with dual-wavelength detection at 214 and 238 nm, and calculation of absorbance ratios. It allowed us to locate the single active-site histidine at position 54 in the primary structure of Streptomyces violaceoruber D-xylose isomerase. The sequence around this residue is conserved in D-xylose isomerases from a diversity of micro-organisms, suggesting that this is a structurally and/or functionally essential part of the molecule.

Aldose-Ketose Isomerases↗

Comparative peptide mapping of a hepatitis C viral recombinant protein by capillary electrophoresis and matrix-assisted laser desorption time-of-flight mass spectrometry.

Capillary electrophoresis (CE) and matrix assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) were investigated as alternatives to sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis for peptide mapping with Staphylococcus aureus protease (V8) of a hydrophobic recombinant hepatitis C virus antigen, HC-31, which required 0.1% SDS for solubility. Controls (V8 only) or HC-31 digests were extracted with chloroform-methanol-water (1:4:3) to remove SDS, which interferes with MALDI-TOF, and high salt content, which affects CE. In two different runs by CE, the elution times of each of 11 peptide peaks were very reproducible (R.S.D. < 0.016). 25 fragments were resolved by MALDI-TOF-MS, including six smaller peptides (M(r) < 13 000) resulting from V8 autodigestion. MALDI-TOF-MS indicated that partial cleavages occurred, primarily at sites where there are paired glutamic and/or aspartic acid residues.

Alkylation↗

Rapid peptide mapping by reversed-phase liquid chromatography on nonporous silica with on-line electrospray time-of-flight mass spectrometry.

Reversed-phase liquid chromatography (LC) using a nonporous silica support has been combined with electrospray (ES) time-of-flight (TOF) mass spectrometry (MS) for the fast separation and mass detection of peptides. Using this LC method, the resolution of a peptide mixture can be completed is less than 35 s. The resulting chromatographic peak widths are less than 1 s wide. Because of the unique nature of a TOF mass analyzer, complete mass spectra can be acquired at a rate which is sufficient to sample these narrow peaks. When compared with conventional LC, the same separation takes nearly 20 min to complete, and the signal-to-noise ratio observed in the total ion chromatogram is dramatically lower due to the influence of increased background noise in the mass spectra. The limit of detection for a low molecular weight peptide, Val-Pro-Leu, was found to be 6 pmol with the total ion chromatogram and 500 fmol with the reconstructed ion chromatogram. A peptide map of horse heart myoglobin, completed in 3.5 min, is shown as an example of the results which can be obtained from combining this fast LC method with fast ES/TOF/MS detection capability.

Animals↗

Structural homologies of cobalamin-binding proteins. Tryptic peptide mapping of intrinsic factor, transcobalamin and haptocorrin from man, hog and rabbit.

We have explored the structural features of cobalamin binding proteins by peptide mapping. The present report is a comparison of the radioiodinated tryptic peptides of intrinsic factor, transcobalamin and haptocorrin from man, hog and rabbit. The results show that the homology between analogous proteins from different species is close for intrinsic factor and transcobalamin and weaker for haptocorrin. The results also suggest the existence of one or more regions which, with minor changes, are conserved among all proteins investigated. This implies a common evolutionary origin for all the cobalamin binding proteins studied.

Animals↗

A simple peptide mapping method by partial filling micellar electrokinetic capillary chromatography with a zwitterionic-nonionic mixed micelle.

A partial filling micellar electrokinetic capillary chromatography (PF-MEKC) method with a mixed micelle system composed of a zwitterionic surfactant named 3-(N,N-dimethylhexadecylammonium)propanesulfonate (PAPS) and a nonionic surfactant polyethylene glycol dodecyl ether (Brij 35) for peptide mapping is described. The method was demonstrated by the separation of tryptic digestion of bovine serum albumin (BSA). The optimal mixed micelle solution was 50 mM NH(4)OH-HCOOH buffer (pH 2.0) containing 32 mM PAPS and 0.6% (m/v) Brij 35. It was found that the mixed micelle system permitted a highly selective separation of the tryptic digestion. The high separation selectivity was probably due to the ion-pairing interaction between the zwitterionic surfactant molecules and the peptides.

Chromatography, Micellar Electrokinetic Capillary↗

Interrelationships of the subgenera of Coryphaenoides (Teleostei: Gadiformes: Macrouridae): synthesis of allozyme, peptide mapping, and DNA sequence data.

DNA sequences of the 12s rRNA mitochondrial gene from 12 species key to the question of the monophyly of the deep-sea fish genus Coryphaenoides (Macrouridae) were analyzed phylogenetically using maximum parsimony and maximum likelihood. The results were compared with those of three previous studies in which allozyme, peptide mapping, and DNA sequence data were similarly analyzed. The allozyme and DNA sequence data suggested that the largest subgenus (Coryphaenoides), which contained most of the species inhabiting continental slopes between approximately 600 and 2000m depth, is monophyletic. Two of the three subgenera containing the species inhabiting abyssal ocean basins below approximately 2000m together formed a sister group to subgenus Coryphaenoides. The macrourids of the abyssal basins and those of the continental slopes thus appear to have experienced separate radiations from a common ancestor.

Animals↗

Peptide Mapping and Primary Structure Analysis of hEGFby Mass Spectrometry.

Liquid chromatography-mass spectrometry(LC-MS) was adopted to analyze peptide mapping of the hEGF digested by TPCK-trypsin and V8 to determine the molecular weight of each peptide fragment. Most of the peptide fragments were sequenced by tandem MS(MS-MS) to obtain the amino acid sequence. In addition, the number of disulfide bonds was confirmed. This method will facilitate the determination and structural analysis for nature, synthesis and recombinant proteins and peptides. The accuracy and resolution are both better than that of the routine method.

Journal Article↗

Isolation of proteins for peptide mapping, amino acid analyses, and sequencing using disulfide crosslinked polyacrylamide gels.

Conditions for recovery of small amounts of proteins (1-50 micrograms) from disulfide crosslinked polyacrylamide gels have been examined. Procedures were developed for solubilization and precipitation of Coomassie blue-stained protein bands excised from gels after electrophoretic separations. The precipitated protein was then resolubilized for use in peptide mapping, amino acid analyses, or microsequencing. The amino acid compositions of standard proteins (bovine albumin, ovalbumin, phosphorylase b, and beta-galactosidase) isolated by this method were in good agreement with the values for the corresponding conventionally purified proteins. Sequencing was done with high repetitive yield on samples of 100 pmol or below. The method has been successfully applied to several proteins and protein fragments.

Amino Acid Sequence↗

Fast detection of phosphorylation of human pepsinogen A, human pepsinogen C and swine pepsinogen using a combination of reversed-phase high-performance liquid chromatography and capillary zone electrophoresis for peptide mapping.

A combination of reversed-phase high-performance liquid chromatography (RP-HPLC) and capillary zone electrophoresis (CZE) was used for characterization of alpha-chymotryptic digests of human pepsinogen A, human pepsinogen C (both isolated from stomach mucosa of patients suffering from gastric cancer), swine pepsinogen and their dephosphorylated forms. Combining RP-HPLC and CZE for peptide mapping allowed to detect phosphorylations in molecules of the above mentioned gastric zymogens. We have found one phosphate group in the molecule of human pepsinogen A and two phosphate groups in the molecule of human pepsinogen C. The investigated sample was obtained from stomach mucosa of a patient suffering from gastric cancer. An increased number of phosphate groups in molecules of human pepsinogen seems to be associated with gastric cancer. The developed method represent a suitable tool for studying relationships between specific phosphorylations of proteins and cancerogenesis or potentially could serve for early diagnosis of gastric cancer.

Animals↗

Highly efficient enrichment and subsequent digestion of proteins in the mesoporous molecular sieve silicate SBA-15 for matrix-assisted laser desorption/ionization mass spectrometry with time-of-flight/time-of-flight analyzer peptide mapping.

Based on a previous study of protein digestion inside the nanoreactor channels of the mesoporous molecular sieve silicate SBA-15 (Chem. Eur. J. 2005, 11: 5391), we have developed a highly efficient enrichment and subsequent tryptic digestion of proteins in SBA-15 for matrix-assisted laser desorption/ionization mass spectrometry with time-of-flight/time-of-flight analyzer (MALDI-TOF/TOF) peptide mapping. The performance of the method is exemplified with myoglobin and cytochrome c. First, protein adsorption isotherms for two standard proteins with a range of initial concentration of proteins were investigated at room temperature. The results revealed that the kinetic adsorption rate of a protein within SBA-15 was independent of initial protein concentration, and a 15-min protein enrichment within SBA-15 could be enough for protein identification in biological samples. It was noticed that no washing steps were needed to avoid protein loss due to desorption from the mesochannels into solution. Second, protein digestion inside the channels of SBA-15 was also optimized. After adsorption of proteins into SBA-15 in 15 min, the trypsin solution (pH 8) was directly added to the SBA-15 beads with immobilized proteins by centrifugation, and then the digestion was performed for 15 min at 37 degrees C. It was observed that a higher peptide sequence covering of 98% for myoglobin was obtained by MALDI-TOF/TOF analysis, compared to in-solution digestion. So the protein digestion inside SBA-15 was proved to be significantly faster and yielded a better sequence coverage. The new procedure allows for rapid protein enrichment and digestion inside SBA-15, and has great potential for protein analysis.

Adsorption↗

Peptide mapping by limited proteolysis in sodium dodecyl sulfate and analysis by gel electrophoresis.

A rapid and convenient method for peptide mapping of proteins has been developed. The technique, which is especially suitable for analysis of proteins that have been isolated from gels containg sodium dodecyl sulfate, involves partial enzymatic proteolysis in the presence of sodium dodecyl sulfate and analysis of the cleavage products by polyacrylamide gel electrophoresis. The pattern of peptide fragments produced is characteristic of the protein substrate and the proteolytic enzyme and is highly reproducible. Several common proteases have been used including chymotrypsin, Staphylococcus aureus protease, and papain.

Alkaline Phosphatase↗

Formic acid as a milder alternative to trifluoroacetic acid and phosphoric acid in two-dimensional peptide mapping.

In reversed-phase chromatography of peptides, formic acid has been shown to successfully replace the stronger traditional trifluoroacetic and phosphoric acids. Detection of non-aromatic peptide at lower wavelength is not impaired and being volatile the acid is easily removed, enabling further studies of the peptides. Also in ion-exchange chromatography (the first step of a two-dimensional approach) formic acid works well with a sulphonic acid ion-exchange resin.

Animals↗

Nanoliter chemistry combined with mass spectrometry for peptide mapping of proteins from single mammalian cell lysates.

A nanoliter-chemistry station combined with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was developed to characterize proteins at the attomole level. Chemical reactions including protein digestion were carried out in nanoliter or subnanoliter volumes, followed by microspot sample deposition of the digest to a MALDI-TOF mass spectrometer. Accurate mass determination of the peptides from the enzyme digest, in conjunction with protein database searching, allowed the identification of the proteins in the protein database. This method is particularly useful for handling small-volume samples such as in single-cell analysis. The high sensitivity and specificity of this method were demonstrated by peptide mapping and identifying hemoglobin variants of sickle cell disease from a single red blood cell. The approach of combining nanoliter chemistry with highly sensitive mass spectrometric analysis should find general use in characterizing proteins from biological systems where only a limited amount of material is available for interrogation.

Animals↗

Comparison of in vivo and in vitro phosphorylation of the exocytosis-sensitive protein PP63/parafusin by differential MALDI mass spectrometric peptide mapping.

PP63 (parafusin) is a 63 kDa phosphoprotein, which exists in at least two different isoforms. It is very rapidly (80 ms) dephosphorylated during triggered trichocyst exocytosis. This occurs selectively in exocytosis-competent Paramecium tetraurelia strains. At least two protein kinases isolated from Paramecium, casein kinase type II kinase and cGMP-dependent kinase, are able to phosphorylate the two recombinant PP63/parafusin isoforms, both with phosphoglucomutase activity, in vitro. By performing mass spectrometric peptide mapping, we have investigated in vitro phosphorylation of recombinant PP63/parafusin by these kinases in comparison to in vivo phosphorylation of native PP63/parafusin isolated from Paramecium homogenates. Low picomolar quantities of proteolytic digests of recombinant and native PP63/parafusin, prior to and following alkaline phosphatase treatment, were directly analyzed by MALDI mass spectrometry. In native PP63-1/parafusin-1, six of 64 serine and threonine residues (S-196, T-205, T-280, T-371, T-373, and T-469) were found definitely, 27 were found possibly phosphorylated, 28 were identified as nonphosphorylated, and three were not covered by mapping. Three of the six certainly phosphorylated amino acids represent consensus phosphorylation sites for casein kinase II or cGMP-dependent protein kinase. In vitro phosphorylation studies of recombinant PP63/parafusin confirm that some of the sites found were used in vivo; however, also significant differences with respect to in vivo phosphorylation of native PP63/parafusin were observed. The two Paramecium protein kinases that were used do not preferably phosphorylate expected consensus sites in vitro. Homology structure modeling of PP63/parafusin with rabbit phosphoglucomutase revealed that the majority of residues found phosphorylated is located on the surface of the molecule.

Amino Acid Sequence↗

The relationship between the flaviviruses Skalica and Langat as revealed by monoclonal antibodies, peptide mapping and RNA sequence analysis.

The flavivirus Skalica was isolated from a bank vole in Czechoslovakia in 1976. It can be serologically distinguished from prototype strains of tick-borne encephalitis (TBE) virus and has a decreased virulence for adult mice. We have further defined the relationship of Skalica virus to other members of the TBE serocomplex (TBE European and Far Eastern subtypes, Langat and louping ill virus) by using a panel of 22 monoclonal antibodies, peptide mapping and RNA sequence analyses. By these criteria Skalica virus proved to be distinct from TBE virus and to be very closely related to Langat virus, differing by only two bases among a total of 416 nucleotides compared. The sequence of 22% of the Langat genome was determined and the encoded amino acid sequences were derived. Comparison of these with the corresponding amino acid sequences of TBE virus revealed a similarity of 85%, as opposed to 93% similarity between the European and Far Eastern subtypes of TBE virus.

Amino Acid Sequence↗

Identification of receptor binding sites by competitive peptide mapping: phages T1, T5, and phi 80 and colicin M bind to the gating loop of FhuA.

Previously we proposed a transmembrane model of the FhuA receptor protein in the outer membrane of Escherichia coli. Removal of the largest loop at the cell surface converted the FhuA transport protein into an open channel and rendered cells resistant to the FhuA-specific phages T1, T5, and phi 80 and to colicin M. In the present study we employed acetylated hexapeptide amides covering the entire surface loop to investigate binding of the phages and of colicin M. Competitive peptide mapping proved to be a powerful technique to uncover three ligand binding sites within a region of 34 amino acid residues. Hexapeptides derived from three specific regions of the surface loop inhibited infection of cells by the phages and killing by colicin M. Two of these regions were common among all four FhuA ligands. Electron microscopy of phage T5 revealed that one inhibitory peptide triggered a strong conformational change leading to the release of DNA from the phage head. These results suggest that the FhuA gating loop is the target for specific binding of phages T1, T5, and phi 80 and colicin M.

Amino Acid Sequence↗