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Takayama M. Sensitive and resistant of the homologous disulfide-bridged proteins α-lactalbumin and lysozyme to attack of hydrogen-atoms, dithiothreitol and trifluoroacetic acid, examined by matrix-assisted laser desorption/ionization mass spectrometry. Biochem Biophys Rep 2022; 29:101212. [PMID: 35111980 PMCID: PMC8790284 DOI: 10.1016/j.bbrep.2022.101212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/26/2021] [Accepted: 01/13/2022] [Indexed: 12/03/2022] Open
Abstract
Background Evolutionarily homologous proteins bovine α-lactoalbumin (αLA) and hen egg-white lysozyme (HEL) are very similar in primary, secondary and tertiary structures involving the location of disulfide-bridges (S–S), and are resistant to the action of hydrolytic enzymes and reagents. It is of interest to examine and compare the difference in backbone cleavage characteristics, by using reductive and hydrolytic reagents. Methods In-source decay (ISD) combined with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS), reductive treatment of αLA and HEL with dithiothreitol (DTT) and acid hydrolysis with trifluoroacetic acid (TFA) were employed to examine the difference in the backbone cleavage characteristics of αLA and HEL. Results The treatment of αLA and HEL with DTT/AcOHNH3 resulted in similar cleavage behaviors of the backbone N-Cα and S–S bonds, i.e., the enhancements of the intensity and m/z range of sequence-reflected fragment ions were very similar. However, the treatment of αLA with DTT/TFA resulted in unexpected residue-specific degradation at the peptide bond of the Asp-Xxx, Xxx-Ser/Thr, Gln-Xxx, Xxx-Gly and Gly-Xxx residues, while HEL did not occur such degradation. Conclusions The results obtained above indicate that acidic αLA is very sensitive to acidic additive such as TFA, while basic HEL is resistance to acidic additives. General significance The study demonstrates the sensitive and resistant of evolutionary homologous proteins αLA and HEL to the acid hydrolysis and these characters come from acidic and basic nature of the proteins. Evolutionary homologous proteins bovine alpha-lactoalbumin and hen egg-white lysozyme are quite different in the protection from acidic reagents. Alpha-lactoalbumin is easily hydrolyzed with acidic reagents at the specific Asp, Gly, Thr and Ser residues owing to the acidic protein with pI4.53 Lysozyme is perfectly resistant to acidic reagents due to the presence of strong basic Arg residues owing to the basic protein with pI10.7 Degradation characteristics at the backbone S–S and N-Cα bonds of both proteins are very similar.
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Marchenkov V, Ryabova N, Balobanov V, Glukhov A, Ilyina N, Katina N. Under Conditions of Amyloid Formation Bovine Carbonic Anhydrase B Undergoes Fragmentation by Acid Hydrolysis. Biomolecules 2021; 11:biom11111608. [PMID: 34827606 PMCID: PMC8615856 DOI: 10.3390/biom11111608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/23/2021] [Accepted: 10/28/2021] [Indexed: 11/23/2022] Open
Abstract
The development of many severe human diseases is associated with the formation of amyloid fibrils. Most of the available information on the process of amyloid formation has been obtained from studies of small proteins and peptides, wherein the features of complex proteins’ aggregation remain insufficiently investigated. Our work aimed to research the amyloid aggregation of a large model protein, bovine carbonic anhydrase B (BCAB). It has previously been demonstrated that, when exposed to an acidic pH and elevated temperature, this protein forms amyloid fibrils. Here, we show that, under these conditions and before amyloid formation, BCAB undergoes fragmentation by acid hydrolysis to give free individual peptides and associated peptides. Fragments in associates contain a pronounced secondary structure and act as the main precursor of amyloid fibrils, wherein free peptides adopt mostly unstructured conformation and form predominantly irregular globular aggregates. Reduced acidity decreases the extent of acid hydrolysis, causing BCAB to form amorphous aggregates lacking the thioflavin T binding β-structure. The presented results provide new information on BCAB amyloid formation and show the importance of protein integrity control when working even in mildly acidic conditions.
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Taga Y, Kusubata M, Mizuno K. Quantitative Analysis of the Positional Distribution of Hydroxyproline in Collagenous Gly-Xaa-Yaa Sequences by LC-MS with Partial Acid Hydrolysis and Precolumn Derivatization. Anal Chem 2020; 92:8427-8434. [PMID: 32437599 DOI: 10.1021/acs.analchem.0c01098] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Collagen is extensively modified by various enzymes, including prolyl hydroxylases. Pro residues at the Yaa position of repeating Gly-Xaa-Yaa amino acid sequences are mostly hydroxylated to 4-hydroxyproline (4Hyp), which is essential for the thermal stability of collagen triple helix. In contrast, Pro residues at the Xaa position are rarely modified to 3Hyp and 4Hyp, the biological function of which is poorly understood. Overall estimation of prolyl hydroxylation with discrimination of the position (Xaa or Yaa) and hydroxylation type (4Hyp or 3Hyp) has been difficult to perform using traditional methods. In the present study, we developed a novel position-specific analytical method featuring LC-MS detection of collagenous Gly-containing dipeptides, including Gly-Pro, Pro-Gly, Gly-4Hyp, Gly-3Hyp, and 4Hyp-Gly, after partial acid hydrolysis and precolumn derivatization using 3-aminopyridyl-N-hydroxysuccinimidyl carbamate (APDS). We performed acid hydrolysis at 55 °C with HCl/trifluoroacetic acid/water (2:1:1, v/v) to avoid peptide inversion and imbalanced peptide generation observed for collagenous model peptides. The positional distribution of Pro, 4Hyp, and 3Hyp can be calculated from the relative concentrations of the APDS-derivatized dipeptides, and in combination with amino acid analysis, we can determine their absolute contents at the Xaa and Yaa positions. Bovine type I, III, and V collagens were analyzed by the established method, and the amount of 4Hyp was higher than that of 3Hyp at the Xaa position in type I and III collagens. In addition, we clearly showed that collagen extracted from earthworm cuticles has an extremely high content of Xaa position 4Hyp, reaching over 10% of the total amino acids.
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Affiliation(s)
- Yuki Taga
- Nippi Research Institute of Biomatrix, 520-11 Kuwabara, Toride, Ibaraki 302-0017, Japan
| | - Masashi Kusubata
- Nippi Research Institute of Biomatrix, 520-11 Kuwabara, Toride, Ibaraki 302-0017, Japan
| | - Kazunori Mizuno
- Nippi Research Institute of Biomatrix, 520-11 Kuwabara, Toride, Ibaraki 302-0017, Japan
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4
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Abstract
Massive evidence suggests that genetic abnormalities contribute to the development of lung cancer. These molecular abnormalities may serve as diagnostic, prognostic and predictive biomarkers for this deadly disease. It is imperative to search these biomarkers in different tumorigenesis pathways so as to provide the most appropriate therapy for each individual patient with lung malignancy. Phosphoproteomics is a promising technology for the identification of biomarkers and novel therapeutic targets for cancer. Thousands of proteins interact via physical and chemical association. Moreover, some proteins can covalently modify other proteins post-translationally. These post-translational modifications ultimately give rise to the emergent functions of cells in sequence, space and time. Phosphoproteomics clinical researches imply the comprehensive analysis of the proteins that are expressed in cells or tissues and can be employed at different stages. In addition, understanding the functions of phosphorylated proteins requires the study of proteomes as linked systems rather than collections of individual protein molecules. In fact, proteomics approaches coupled with affinity chromatography strategies followed by mass spectrometry have been used to elucidate relevant biological questions. This article will discuss the relevant clues of post-translational modifications, phosphorylated proteins, and useful proteomics approaches to identify molecular cancer signatures. The recent progress in phosphoproteomics research in lung cancer will be also discussed.
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Affiliation(s)
- Elena López
- Hospital Universitario Niño Jesús, Department of Oncohematology of Children, Madrid 28009, Spain; E-Mail:
| | - William C. S. Cho
- Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +852-295-854-41; Fax: +852-295-854-55
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Remily-Wood E, Dirscherl H, Koomen JM. Acid hydrolysis of proteins in matrix assisted laser desorption ionization matrices. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:2106-2115. [PMID: 19679491 DOI: 10.1016/j.jasms.2009.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 07/01/2009] [Accepted: 07/07/2009] [Indexed: 05/28/2023]
Abstract
Sample preparation is crucial to the success of experiments in biological mass spectrometry. In proteomics, digestion of the proteins into peptides is a key step for "bottom-up" approaches. Often, the use of enzymes requires physiological conditions, producing peptides that must be extracted or further purified before mass analysis. Chemical cleavage reagents offer more flexibility and can be more compatible with downstream mass analysis. Expanding on prior work using acid hydrolysis, proteolysis with matrix-assisted laser desorption ionization (MALDI) matrices is presented. This sample preparation can be performed rapidly with a minimum of reagents and sample handling, but it must first be evaluated in terms of digestion efficiency, missed cleavages, and side reactions before implementation for in-gel digestion and in-solution digestion using minimal volumes of protein. Time courses of acid hydrolysis are shown for protein standards, illustrating the sensitivity of this type of sample preparation, minimization of side reactions, and performance for proteins in mixtures. To illustrate the potential for sensitive detection of a specific protein, MALDI matrix hydrolysis is used to digest a protein immunoprecipitated from cell lysate.
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Affiliation(s)
- Elizabeth Remily-Wood
- Molecular Oncology and Proteomics, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612, USA
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6
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Granvogl B, Plöscher M, Eichacker LA. Sample preparation by in-gel digestion for mass spectrometry-based proteomics. Anal Bioanal Chem 2007; 389:991-1002. [PMID: 17639354 DOI: 10.1007/s00216-007-1451-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Revised: 06/14/2007] [Accepted: 06/20/2007] [Indexed: 10/23/2022]
Abstract
The proteomic characterization of proteins and protein complexes from cells and cell organelles is the next challenge for investigation of the cell. After isolation of the cell compartment, three steps have to be performed in the laboratory to yield information about the proteins present. The protein mixtures must be separated into single species, broken down into peptides, and, finally, identified by mass spectrometry. Most scientists engaged in proteomics separate proteins by electrophoresis. For characterization and identification of proteomes, mass spectrometry of peptides is the method of choice. To combine electrophoresis and mass spectrometry, sample preparation by "in-gel digestion" has been developed. Many procedures are available for in-gel digestion, which inspired us to review in-gel digestion approaches.
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Affiliation(s)
- Bernhard Granvogl
- Department für Biologie I, Ludwig-Maximilians-Universität, Menzinger Strasse 67, 80638, München, Germany
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7
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Gebremedhin M, Zhong H, Wang S, Weinfeld M, Li L. Benefit of microwave-assisted acid hydrolysis of proteins for mass spectrometric profiling of the human heart tissue proteome. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2007; 21:2779-83. [PMID: 17654473 DOI: 10.1002/rcm.3125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
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8
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Loo RRO, Loo JA. Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry of Hydrophobic Proteins in Mixtures Using Formic Acid, Perfluorooctanoic Acid, and Sorbitol. Anal Chem 2006; 79:1115-25. [PMID: 17263344 DOI: 10.1021/ac061916c] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Three MALDI-MS sample/matrix preparation approaches were evaluated for their ability to enhance hydrophobic protein detection from complex mixtures: (1) formic acid-based formulations, (2) perfluorooctanoic acid (PFOA) surfactant addition, and (3) sorbitol addition. While MALDI-MS of Escherichia coli cells desorbed from a standard sinapinic acid matrix displayed 94 (M + H)+ ions, 119 were observed from a formic acid-based matrix with no more than 10 common to both. Formic acid matrix revealed many lipoproteins and an 8282 m/z ion proposed to be the abundant, water-insoluble ATPase proteolipid. Among the formic acid-based cocktails examined, the slowest rate of serine/threonine formylation was found for 50% H2O/33% 2-propanol/17% formic acid. Faster formylation was observed from cocktails containing more formic acid and from mixtures including CH3CN. Sinapinic, ferulic, DHB, 4-hydroxybenzylidene malononitrile, and 2-mercaptobenzothiazole matrixes performed well in formic acid formulations. Dramatic differences in mixture spectra were also observed from PFOA/sinapinic acid, at detergent concentrations exceeding the critical micelle concentration, although these matrix cocktails proved difficult to crystallize. E. coli ions observed from these matrix conditions are listed in Tables S-1 and S-3 (Supporting Information). Similar complementarity was observed for M. acetivorans whole-cell mixtures. Including sorbitol in the sinapinic acid matrix was found to promote homogeneous crystallization and to enhance medium and higher m/z ion detection from dilute E. coli cellular mixtures.
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Affiliation(s)
- Rachel R Ogorzalek Loo
- Department of Biological Chemistry and Department of Chemistry & Biochemistry, Molecular Biology Institute, UCLA-DOE Institute for Genomics & Proteomics, University of California-Los Angeles, Los Angeles, California 90095, USA.
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Zhong H, Marcus SL, Li L. Microwave-assisted acid hydrolysis of proteins combined with liquid chromatography MALDI MS/MS for protein identification. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2005; 16:471-81. [PMID: 15792716 DOI: 10.1016/j.jasms.2004.12.017] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2004] [Revised: 12/23/2004] [Accepted: 12/23/2004] [Indexed: 05/13/2023]
Abstract
Simple and efficient digestion of proteins, particularly hydrophobic membrane proteins, is of significance for comprehensive proteome analysis using the bottom-up approach. We report a microwave-assisted acid hydrolysis (MAAH) method for rapid protein degradation for peptide mass mapping and tandem mass spectrometric analysis of peptides for protein identification. It uses 25% trifluoroacetic acid (TFA) aqueous solution to dissolve or suspend proteins, followed by microwave irradiation for 10 min. This detergent-free method generates peptide mixtures that can be directly analyzed by liquid chromatography (LC) matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) without the need of extensive sample cleanup. LC-MALDI MS/MS analysis of the hydrolysate from 5 microg of a model transmembrane protein, bacteriorhodopsin, resulted in almost complete sequence coverage by the peptides detected, including the identification of two posttranslational modification sites. Cleavage of peptide bonds inside all seven transmembrane domains took place, generating peptides of sizes amenable to MS/MS to determine possible sequence errors or modifications within these domains. Cleavage specificity, such as glycine residue cleavage, was observed. Terminal peptides were found to be present in relatively high abundance in the hydrolysate, particularly when low concentrations of proteins were used for MAAH. It was shown that these peptides could still be detected from MAAH of bacteriorhodopsin at a protein concentration of 1 ng/microl or 37 fmol/microl. To evaluate the general applicability of this method, it was applied to identify proteins from a membrane protein enriched fraction of cell lysates of human breast cancer cell line MCF7. With one-dimensional LC-MALDI MS/MS, a total of 119 proteins, including 41 membrane-associated or membrane proteins containing one to 12 transmembrane domains, were identified by MS/MS database searching based on matches of at least two peptides to a protein.
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Affiliation(s)
- Hongying Zhong
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
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10
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Investigation of Angiotensin Glycosylation by MALDI-TOF and ESI Tandem Mass Spectrometry. B KOREAN CHEM SOC 2004. [DOI: 10.5012/bkcs.2004.25.12.1791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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11
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Zhong H, Zhang Y, Wen Z, Li L. Protein sequencing by mass analysis of polypeptide ladders after controlled protein hydrolysis. Nat Biotechnol 2004; 22:1291-6. [PMID: 15361881 DOI: 10.1038/nbt1011] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Accepted: 07/23/2004] [Indexed: 11/08/2022]
Abstract
The characterization of protein modifications is essential for the study of protein function using functional genomic and proteomic approaches. However, current techniques are not efficient in determining protein modifications. We report an approach for sequencing proteins and determining modifications with high speed, sensitivity and specificity. We discovered that a protein could be readily acid-hydrolyzed within 1 min by exposure to microwave irradiation to form, predominantly, two series of polypeptide ladders containing either the N- or C-terminal amino acid of the protein, respectively. Mass spectrometric analysis of the hydrolysate produced a simple mass spectrum consisting of peaks exclusively from these polypeptide ladders, allowing direct reading of amino acid sequence and modifications of the protein. As examples, we applied this technique to determine protein phosphorylation sites as well as the sequences and several previously unknown modifications of 28 small proteins isolated from Escherichia coli K12 cells. This technique can potentially be automated for large-scale protein annotation.
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12
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Fernandez Ocaña M, Neubert H, Przyborowska A, Parker R, Bramley P, Halket J, Patel R. BSE control: detection of gelatine-derived peptides in animal feed by mass spectrometry. Analyst 2003; 129:111-5. [PMID: 14752552 DOI: 10.1039/b312593a] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The epidemic of bovine spongiform encephalopathy (BSE) is thought to have resulted from feeding scrapie-infected sheep to cattle. This has led to a ban of feeding animals with "processed animal protein"(PAP). We report a novel approach for the mass spectrometric detection of PAP contamination in animal feedstuffs by detecting gelatine, a derivative of the major animal protein collagen. A method was developed to hydrolyse gelatine standards with hydrochloric acid, followed by detection of the derived hydrolytic peptides at m/z 828, 915, 957 and 1044 by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography electrospray ionisation mass spectrometry (LC-ESI-MS-MS). The marker peptides can be detected at concentrations of 100 ng ml(-1) gelatine in water with MALDI. The procedure was adapted to obtain a suitable peptide map of gelatine extracted from spiked feed. The ratio of signal area of the gelatine-derived peptide at m/z 1044 to the internal standard at m/z 556 is shown to relate to the total amount of gelatine present in the sample.
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Affiliation(s)
- Mireia Fernandez Ocaña
- Centre for Chemical and Bioanalytical Sciences, Royal Holloway University of London, Egham, UK W20 0EX.
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13
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Li A, Sowder RC, Henderson LE, Moore SP, Garfinkel DJ, Fisher RJ. Chemical cleavage at aspartyl residues for protein identification. Anal Chem 2001; 73:5395-402. [PMID: 11816565 DOI: 10.1021/ac010619z] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An alternative method to enzymatic digestion for protein identification by mass spectrometry has been developed that is based on chemical cleavage by formic acid. This method was tested on gel-purified apomyoglobin and BSA, as well as unknown proteins that cofractionate with Tyl-virus-like particles from Saccharomyces cerevisiae. Cleavage at aspartyl residues was found to be efficient and specific, and this specificity of cleavage lent itself easily to database searches. Parallel digestions using trypsin were also performed. The formic acid cleavage method generated comparable or better results than tryptic digestion for protein identification.
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Affiliation(s)
- A Li
- Protein Chemistry Laboratory, AIDS Vaccine Program, SAIC Frederick, NCI at Frederick, Maryland 21702-1201, USA.
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14
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Affiliation(s)
- R Aebersold
- Institute for Systems Biology, 4225 Roosevelt Way NE, Seattle, Washington 98105, USA.
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15
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16
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Marzilli LA, Golden TR, Cotter RJ, Woods AS. Peptide sequence information derived by pronase digestion and ammonium sulfate in-source decay matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2000; 11:1000-1008. [PMID: 11073263 DOI: 10.1016/s1044-0305(00)00170-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We present the use of Pronase digestion and in-source decay in the presence of ammonium sulfate as complementary techniques to confirm the amino acid sequence of a peptide. Pronase, a commercial preparation from Streptomyces griseus, is a combination of proteolytic enzymes. It produces carboxypeptidase and aminopeptidase ladders using a single Pronase digestion and represents an inexpensive, nonspecific, and fast supplement to traditional sequencing enzymes. However, N-terminal peptidase activity appears dependent on the terminal amino acid residue. We also introduce the use of saturated ammonium sulfate as an "on-slide" sample additive to promote in-source fragmentation of peptides. Use of saturated ammonium sulfate resulted in a simple way to increase peptide backbone fragmentation and essentially produced either a cn or yn ion series. Together these techniques provide useful supplements to existing methods for peptide sequence information.
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Affiliation(s)
- L A Marzilli
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, USA
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17
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Abstract
Accurate definition of the carboxyl terminal of proteins is necessary for elucidating posttranslational processing at the C-terminal and more generally for characterizing protein primary structures. Here, we describe a strategy for isolating and characterizing the C-terminal peptide of a protein after proteolysis with endoprotease Lys-C. Isolation is achieved using anhydrotrypsin, a catalytically inert derivative of trypsin that binds peptides containing lysine or arginine residues at their C-termini without cleaving them. Rapid, accurate characterization of the isolated C-terminal peptide is achieved by mass spectrometry. Initial identification of the C-terminal peptide is obtained by comparing matrix-assisted laser desorption/ionization time-of-flight mass spectra of the digest prior to and after incubation with anhydrotrypsin. Characterization of the C-terminal sequence is achieved by capillary-HPLC electrospray ionization tandem mass spectrometry of the isolated peptide using a quadrupole ion trap mass spectrometer in the selective reaction monitoring mode. This strategy was successfully applied to the characterization of the C-terminal of proteins with molecular masses ranging up to 56 kDa.
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Affiliation(s)
- S Sechi
- Laboratory for Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, New York 10021, USA
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Shevchenko A, Loboda A, Shevchenko A, Ens W, Standing KG. MALDI quadrupole time-of-flight mass spectrometry: a powerful tool for proteomic research. Anal Chem 2000; 72:2132-41. [PMID: 10815976 DOI: 10.1021/ac9913659] [Citation(s) in RCA: 230] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A MALDI QqTOF mass spectrometer has been used to identify proteins separated by one-dimensional or two-dimensional gel electrophoresis at the femtomole level. The high mass resolution and the high mass accuracy of this instrument in both MS and MS/MS modes allow identification of a protein either by peptide mass fingerprinting of the protein digest or from tandem mass spectra acquired by collision-induced dissociation of individual peptide precursors. A peptide mass map of the digest and tandem mass spectra of multiple peptide precursor ions can be acquired from the same sample in the course of a single experiment. Database searching and acquisition of MS and MS/MS spectra can be combined in an interactive fashion, increasing the information value of the analytical data. The approach has demonstrated its usefulness in the comprehensive characterization of protein in-gel digests, in the dissection of complex protein mixtures, and in sequencing of a low molecular weight integral membrane protein. Proteins can be identified in all types of sequence databases, including an EST database. Thus, MALDI QqTOF mass spectrometry promises to have remarkable potential for advancing proteomic research.
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Affiliation(s)
- A Shevchenko
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
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Gustavsson N, Härndahl U, Emanuelsson A, Roepstorff P, Sundby C. Methionine sulfoxidation of the chloroplast small heat shock protein and conformational changes in the oligomer. Protein Sci 1999; 8:2506-12. [PMID: 10595556 PMCID: PMC2144199 DOI: 10.1110/ps.8.11.2506] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The small heat shock proteins (sHsps), which counteract heat and oxidative stress in an unknown way, belong to a protein family of sHsps and alpha-crystallins whose members form large oligomeric complexes. The chloroplast-localized sHsp, Hsp21, contains a conserved methionine-rich sequence, predicted to form an amphipatic helix with the methionines situated along one of its sides. Here, we report how methionine sulfoxidation was detected by mass spectrometry in proteolytically cleaved peptides that were produced from recombinant Arabidopsis thaliana Hsp21, which had been treated with varying concentrations of hydrogen peroxide. Sulfoxidation of the methionine residues in the conserved amphipatic helix coincided with a significant conformational change in the Hsp21 protein oligomer.
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Affiliation(s)
- N Gustavsson
- Department of Biochemistry, Lund University, Sweden
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