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PubMed2005

Proteomics: the next revolution in laboratory medicine?

BACKGROUND: The identification of specific genetic alterations and protein profiles associated with disease offers a unique opportunity to develop proteomics-based assays for early diagnosis. By identifying proteins in serum/plasma, a minimally invasive tool is used to assess the presence of disease and to monitor response to treatment and/or disease progression. The potential clinical applications of this tool are broad-based, including the diagnosis not only of cancer but also cardiovascular and neuromuscular diseases, organ transplantation associated conditions, and infertility. METHODS: A number of competing chromatographic techniques have been proposed for overcoming the complexity and labor-intensive manipulations associated with the traditional technique for proteomic analysis, which is based on two-dimensional gel electrophoretic techniques. However, mass spectrometry has now assumed a central role in most proteomic workflows, and several combinations of ionization sources, analyzers and fragmentations devices have been described and developed. RESULTS: Thanks to proteomic applications in the diagnosis of cancer, several research groups have identified proteomic patterns associated with ovarian, prostatic, colorectal and other cancers. While the sensitivity and specificity of these patterns are highly satisfactory, there are still some open questions concerning the standardization, reproducibility, and inter-laboratory agreement of these data. CONCLUSIONS: Proteomics, and, in particular, serum mass spectroscopic proteomic pattern diagnostics, is a rapid expanding field of research. The plasma proteoma has an important position at the intersection between genes and diseases, and clinical laboratories must adapt to a new era of tests based on proteomics and genomics. In the future, mass spectrometry will become an essential tool in the clinical laboratory.

Biomarkers, Tumor↗
PubMed2005

Role of chromatographic techniques in proteomic analysis.

Proteomics, the characterization of the proteome, is conceptually simple but technically challenging. Development of such technologies as mass spectrometry, multidimensional protein separation, and DNA sequencing has allowed the new field of proteomics to flourish. Proteomic analysis relies on a set of techniques chosen on the basis of the biological question. In any proteomic analysis, the first and most important task is the separation of a complex protein mixture, i.e. the proteome. Chromatography, one of the most powerful methods of separation, employs one or more inherent characteristics of a protein-its mass, isoelectric point, hydrophobicity or biospecificity. This review emphasizes high-performance liquid chromatography as an integrated part of technologies used to study the proteome, discusses the capabilities and limitations of current instruments, and highlights the potential of multidimensional liquid chromatography in proteomic analysis.

Chromatography, Affinity↗
PubMed2001

Proteomic profiling from human samples: the body fluid alternative.

Proteomics is one of the technologies rapidly changing our approach to drug development. The applications of proteomics, particularly with reference to analysis of body fluid samples, will be described. Proteomic analysis involves the systematic separation, identification and characterisation of proteins present in a biological sample. By comparing the proteins present in diseased samples with those present in normal samples, it is possible to identify changes in expression of proteins that potentially may be related to organ toxicity. Proteomics is regarded as a sister technology to genomics. Although the pattern of gene activity will be abnormal in a tissue with a pathological lesion, there can be a poor correlation between the level of activity of different genes and the relative abundance within the tissue of the corresponding proteins. This is especially true where the mode of action of the test material interferes with protein synthesis and/or post translational modification. Consequently, the information about a pathological process that can be derived at the level of gene activity is incomplete. Proteomics has now made it possible to analyse proteins using high throughput, automated techniques. Although both mRNA and proteomic profiling can be applied to tissue samples, analysis of body fluids (e.g. serum, urine, CSF, synovial fluid) is restricted to proteomics. In these cases the protein composition is derived from many tissues and processes. Proteomic analysis can yield information on disease processes and potential response to treatment. Examples will be presented of the identification of surrogate markers for hepatocellular carcinoma, breast cancer, from cerebrospinal fluid in humans and gentamicin toxicity in the rat.

Body Fluids↗
PubMed2001

Profiling the specific reactivity of the proteome with non-directed activity-based probes.

BACKGROUND: The field of proteomics aims to characterize dynamics in protein function on a global level. However, several classes of proteins, in particular low abundance proteins, remain difficult to characterize using standard proteomics technologies. Recently, chemical strategies have emerged that profile classes of proteins based on activity rather than quantity, thereby greatly facilitating the analysis of low abundance constituents of the proteome. RESULTS: In order to expand the classes of proteins susceptible to analysis by activity-based methods, we have synthesized a library of biotinylated sulfonate esters and applied its members to complex proteomes under conditions that distinguish patterns of specific protein reactivity. Individual sulfonates exhibited unique profiles of proteome reactivity that in extreme cases appeared nearly orthogonal to one another. A robustly labeled protein was identified as a class I aldehyde dehydrogenase and shown to be irreversibly inhibited by members of the sulfonate library. CONCLUSIONS: Through screening the proteome with a non-directed library of chemical probes, diverse patterns of protein reactivity were uncovered. These probes labeled protein targets based on properties other than abundance, circumventing one of the major challenges facing contemporary proteomics research. Considering further that the probes were found to inhibit a target enzyme's catalytic activity, the methods described herein should facilitate the identification of compounds possessing both selective proteome reactivities and novel bioactivities.

Aldehyde Dehydrogenase↗
PubMed2000

Utility of accurate mass tags for proteome-wide protein identification.

An enabling capability for proteomics would be the ability to study protein expression on a global scale. While several different separation and analysis options are being investigated to advance the practice of proteomics, mass spectrometry (MS) is rapidly becoming the core instrumental technology used to characterize the large number of proteins that constitute a proteome. To be most effective, proteomic measurements must be high-throughput, ideally allowing thousands of proteins to be identified on a time scale of hours. Most strategies of identification by MS rely on the analysis of enzymatically produced peptides originating from an isolated protein followed by either peptide mapping or tandem MS (MS/MS) to obtain sequence information for a single peptide. In the case of peptide mapping, several peptide masses are needed to unambiguously identify a protein with the typically achieved mass measurement accuracies (MMA). The ability to identify proteins based on the mass of a single peptide (i.e., an accurate mass tag; AMT) is proposed and is largely dependent on the MMA that can be achieved. To determine the MMA necessary to enable the use of AMTs for proteome-wide protein identification, we analyzed the predicted proteins and their tryptic fragments from Saccharomyces cerevisiae and Caenorhabditis elegans. The results show that low ppm (i.e., approximately 1 ppm) level measurements have practical utility for analysis of small proteomes. Additionally, up to 85% of the peptides predicted from these organisms can function as AMTs at sub-ppm MMA levels attainable using Fourier transform ion cyclotron resonance MS. Additional information, such as sequence constraints, should enable even more complex proteomes to be studied at more modest mass measurement accuracies. Once AMTs are established, subsequent high-throughput measurements of proteomes (e.g., after perturbations) will be greatly facilitated.

Cyclotrons↗
PubMed2026

A Robust, Self-Digestion-Resistant LysN with Superior Activity and Cleavage Fidelity for Advanced Proteomic Workflows.

LysN is a valuable protease in proteomics because it cleaves peptide bonds N-terminal to lysine, generating peptides with physicochemical properties complementary to those produced by LysC and trypsin. However, the broader adoption of LysN in proteomic workflows has been limited by the lack of commercially available enzymes that combine high activity, low missed-cleavage rates, and sufficient stability under practical sample-processing conditions. Here, we report the recombinant production and proteomic characterization of a self-digestion-resistant and highly active LysN from Shewanella loihica (SL-LysN). Using terminomics, we mapped the mature N- and C-termini of the enzyme and established the primary structure of the active protease. We further developed a high-density fermentation, refolding, and purification workflow to obtain highly purified recombinant SL-LysN. Biochemical and proteomic benchmarking showed that SL-LysN displayed 3.3-fold higher specific activity than commercial LysN and reduced missed cleavages by approximately 80%. Notably, SL-LysN retained high activity in the presence of 8 M urea or 1% SDS and showed strong resistance to autolysis, indicating exceptional robustness for proteomic sample preparation. In complex mammalian proteome digests, SL-LysN achieved >95% cleavage specificity and a missed-cleavage rate of only 5.9%. These features address a long-standing bottleneck in N-terminal proteolysis and establish SL-LysN as a high-performance enzymatic tool for advanced proteomic workflows, including deep protein sequencing, quantitative proteomics, terminomics, de novo sequencing and analyses requiring efficient digestion under denaturing conditions.

Shewanella↗
PubMed2006

The proteomic reactor: a microfluidic device for processing minute amounts of protein prior to mass spectrometry analysis.

Gel-free proteomics has emerged as a complement to conventional gel-based proteomics. Gel-free approaches focus on peptide or protein fractionation, but they do not address the efficiency of protein processing. We report the development of a microfluidic proteomic reactor that greatly simplifies the processing of complex proteomic samples by combining multiple proteomic steps. Rapid extraction and enrichment of proteins from complex proteomic samples or directly from cells are readily performed on the reactor. Furthermore, chemical and enzymatic treatments of proteins are performed in 50 nL effective volume, which results in an increased number of generated peptides. The products are compatible with mass spectrometry. We demonstrated that the proteomic reactor is at least 10 times more sensitive than current gel-free methodologies with one protein identified per 440 pg of protein lysate injected on the reactor. Furthermore, as little as 300 cells can be directly introduced on the proteomic reactor and analyzed by mass spectrometry.

Animals↗
PubMed2006

Proteomic methods in nutrition.

PURPOSE OF REVIEW: Proteomics, the comprehensive analysis of a protein complement in a cell, tissue or biological fluid at a given time, is a key player in the family of -omic disciplines, which encompass genomics (gene analysis), transcriptomics (gene expression analysis) and metabolomics (metabolite profiling). This review summarizes the state of the art of proteomics technology and puts it into perspective for food-related research. Learning from proteomic experiences in the pharmaceutical context, this article may help to translate proteomics into nutrition and health. RECENT FINDINGS: Mass spectrometric technology has progressed enormously with regard to mass accuracy, resolution and peptide sequencing power. Likewise, upstream separation, depletion and enrichment techniques now allow us to deal with the large complexity and wide dynamic range of proteomic samples more efficiently. Consequently, proteomic studies now provide a broader, but still far from complete, coverage of a given proteome. SUMMARY: Proteomics adapted and applied to the context of nutrition and health has the potential to deliver biomarkers for health and comfort, reveal early indicators of disease disposition, assist in differentiating dietary responders from non-responders, and, last but not least, discover bioactive, beneficial food components.

Biomarkers↗
PubMed2005

Proteomics in prostate cancer.

PURPOSE OF REVIEW: State-of-the-art proteomics technologies are currently being assessed for utility in the study of prostatic malignancy. This review aims to provide background information on the current proteomics techniques employed in prostate cancer research, recent reports showing the potential application of proteomics in urological practice, and the future direction of proteomics in prostate cancer research and management. RECENT FINDINGS: Proteomic profiling of serum as a diagnostic tool and a platform for biomarker discovery in prostate cancer continues to draw favorable attention as well as close scrutiny as technological enhancements and multi-center study results are reported. In-vitro studies on prostate cell lines provide positive proof-of-principle results. The application of proteomics to query prostate tissue specimens yields novel prostate cancer biomarkers requiring further validation. The integration of proteomics with immunology also yields promising findings that may translate into clinically relevant biological assays. SUMMARY: The study of proteomics is an emerging research field, and current studies continue to display potential future usage in prostate cancer management. Succeeding scientific investigations will probably yield new diagnostic and prognostic tools for prostate cancer, provide insights into its underlying biology, and contribute to the development of novel treatment strategies.

Gene Expression↗
PubMed2002

Structural characterization of the human proteome.

This paper reports an analysis of the encoded proteins (the proteome) of the genomes of human, fly, worm, yeast, and representatives of bacteria and archaea in terms of the three-dimensional structures of their globular domains together with a general sequence-based study. We show that 39% of the human proteome can be assigned to known structures. We estimate that for 77% of the proteome, there is some functional annotation, but only 26% of the proteome can be assigned to standard sequence motifs that characterize function. Of the human protein sequences, 13% are transmembrane proteins, but only 3% of the residues in the proteome form membrane-spanning regions. There are substantial differences in the composition of globular domains of transmembrane proteins between the proteomes we have analyzed. Commonly occurring structural superfamilies are identified within the proteome. The frequencies of these superfamilies enable us to estimate that 98% of the human proteome evolved by domain duplication, with four of the 10 most duplicated superfamilies specific for multicellular organisms. The zinc-finger superfamily is massively duplicated in human compared to fly and worm, and occurrence of domains in repeats is more common in metazoa than in single cellular organisms. Structural superfamilies over- and underrepresented in human disease genes have been identified. Data and results can be downloaded and analyzed via web-based applications at http://www.sbg.bio.ic.ac.uk.

Algorithms↗
PubMedDate not supplied

Enabling proteomics discovery through visual analysis. The peptide permutation and protein prediction tool.

Proteins play a key role in cellular processes, making proteomics central to understanding systems biology. MS techniques provide a means to observe entire proteomes at a global level. Yet, high-throughput MS proteomics techniques generate data faster than it can currently be analyzed. The success of proteomics depends on high-throughput experimental techniques coupled with sophisticated visual analysis and data-mining methods. Visual analysis has been applied successfully in a number of fields plagued with huge, complex data sets and will likely be an important tool in proteomics discovery. PQuad, a novel visualization of MS proteomics data, provides powerful analysis capabilities that support a number of proteomic data applications. In particular, PQuad supports differential proteomics by simplifying the comparison of peptide sets from different experimental conditions as well as different protein identification or confidence scoring techniques. Finally, PQuad supports data validation and quality control by providing a variety of resolutions for huge amounts of data to reveal errors undetected by other methods.

Algorithms↗
PubMed2006

Proteomics: recent applications and new technologies.

Interest in proteomics as a tool for drug development and a myriad of other applications continues to expand at a rapid rate. Proteomic analyses have recently been conducted on tissues, biofluids, subcellular components and enzymatic pathways as well as various disease and toxicological states, in both animal models and man. In addition, several recent studies have attempted to integrate proteomics data with genomics and/or metabonomics data in a systems biology approach. The translation of proteomic technology and bioinformatics tools to clinical samples, such as in the areas of disease and toxicity biomarkers, represents one of the major opportunities and challenges facing this field. An ongoing challenge in proteomics continues to be the analysis of the serum proteome due to the vast number and complexity of proteins estimated to be present in this biofluid. Aside from the removal of the most abundant proteins, a number of interesting approaches have recently been suggested that may help reduce the overall complexity of serum analysis. In keeping with the increasing interest in applications of proteomics, the tools available for proteomic analyses continue to improve and expand. For example, enhanced tools (such as software and labeling procedures) continue to be developed for the analysis of 2D gels and protein quantification. In addition, activity-based probes are now being used to tag, enrich and isolate distinct sets of proteins based on enzymatic activity. One of the most active areas of development involves microarrays. Antibody-based microarrays have recently been released as commercial products while numerous additional capture agents (e.g. aptamers) and many additional types of microarrays are being explored.

Animals↗
PubMed2002

Molecular biologist's guide to proteomics.

The emergence of proteomics, the large-scale analysis of proteins, has been inspired by the realization that the final product of a gene is inherently more complex and closer to function than the gene itself. Shortfalls in the ability of bioinformatics to predict both the existence and function of genes have also illustrated the need for protein analysis. Moreover, only through the study of proteins can posttranslational modifications be determined, which can profoundly affect protein function. Proteomics has been enabled by the accumulation of both DNA and protein sequence databases, improvements in mass spectrometry, and the development of computer algorithms for database searching. In this review, we describe why proteomics is important, how it is conducted, and how it can be applied to complement other existing technologies. We conclude that currently, the most practical application of proteomics is the analysis of target proteins as opposed to entire proteomes. This type of proteomics, referred to as functional proteomics, is always driven by a specific biological question. In this way, protein identification and characterization has a meaningful outcome. We discuss some of the advantages of a functional proteomics approach and provide examples of how different methodologies can be utilized to address a wide variety of biological problems.

Amino Acid Sequence↗
PubMed2005

Standardized approach to proteome profiling of human serum based on magnetic bead separation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

BACKGROUND: Magnetic bead purification for the analysis of low-abundance proteins in body fluids facilitates the identification of potential new biomarkers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The aims of our study were to establish a proteome fractionation technique and to validate a standardized blood sampling, processing, and storage procedure for proteomic pattern analysis. METHODS: We used magnetic bead separation for proteome profiling of human blood by MALDI-TOF MS (mass range, 1000-10,000 Da) and studied the effects on the quality and reproducibility of the proteome analysis of anticoagulants, blood clotting, time and temperature of sample storage, and the number of freeze-thaw cycles of samples. RESULTS: The proteome pattern of human serum was characterized by approximately 350 signals in the mass range of 1000-10,000 Da. The proteome profile showed time-dependent dynamic changes before and after centrifugation of the blood samples. Serum mass patterns differed between native samples and samples frozen once. The best reproducibility of proteomic patterns was with a single thawing of frozen serum samples. CONCLUSION: Application of the standardized preanalytical blood sampling and storage procedure in combination with magnetic bead-based fractionation decreases variability of proteome patterns in human serum assessed by MALDI-TOF MS.

Adult↗
PubMed2006

Role and challenges of proteomics in pharma and biotech: technical, scientific and commercial perspective.

Contemporary proteomics, currently in its exponential growth phase, is a bewildering array of tools. Proteomic methods are the result of a convergence of rapidly improving mass spectrometry technologies, protein chemistry and separation sciences, genomics and bioinformatics. Strides in improving proteomics technologies to map and measure proteomes and subproteomes are being made. However, no single proteomic platform appears ideally suited to address all research needs or accomplish ambitious goals satisfactorily. However, proteomics is in a unique position to contribute to protein discovery and to public health in terms of better biomarkers, diagnostics and treatment of disease. While the potential is great, many challenges and issues remain to be solved. Fundamental issues, such as biological variability, pre-analytic factors and analytical reproducibility, remain to be resolved. Neither an all-genetic approach nor an all-proteomic approach will solve biological complexity. Proteomics will be the foundation for constructing and extracting useful knowledge to pharma and biotech depicted in the following path: data --> structured data --> information --> information architecture --> knowledge --> useful knowledge.

Animals↗
PubMed2004

Proteomics: state of the art and its application in cardiovascular research.

The cellular and molecular mechanisms underlying cardiovascular dysfunctions are widely unknown. Basically, pathological changes in the cardiovascular system arise from protein alterations. Proteomics comprises a set of tools for the large-scale study of gene expression at the protein level thereby allowing for the identification of protein alterations responsible for the development and the pathological outcome of diseases including those of the cardiovascular system. In principle these alterations include those of suitable candidates for drug targets and disease biomarkers as well as therapeutic proteins/peptides. Since gene therapy depends on the function of a therapeutic protein encoded by a "therapeutic" gene proteomic analyses also provide the basis for the design and application of gene therapies. Proteomic technologies allow to identify not only proteins but also the nature of their posttranslational modifications thus enabling the elucidation of signal transduction pathways and their deregulation under pathological conditions. The linkage of information about proteome changes with functional consequences lead to the development of functional proteomic studies. Functional proteomic analyses will particularly help to better understand the relations between proteome changes and cardiovascular dysfunctions. The storage and administration of experimental data obtained by the application of proteomic analyses is supported by species- and tissue-specific protein databases and specific software. Publications in this field are reviewed in this paper.

Animals↗
PubMed2002

Primer on medical genomics. Part IV: Expression proteomics.

Proteomics, simply defined, is the study of proteomes. More completely, proteomics is defined as the study of all proteins, including their relative abundance, distribution, posttranslational modifications, functions, and interactions with other macromolecules, in a given cell or organism within a given environment and at a specific stage in the cell cycle. Proteins carry out the biological functions encoded by genes; hence, once the initial stage of genome sequencing and gene discovery is completed, a study of the proteome must be undertaken to address fundamental biological questions. The 3 broad areas are expression proteomics, which catalogues the relative abundance of proteins; cell-mapping or cellular proteomics, which delineates functional protein-protein interactions and organelle-specific protein distribution; and structural proteomics, which characterizes the 3-dimensional structure of proteins. With these approaches, proteins are studied on a global scale using a synergistic combination of powerful, high-throughput technologies, including 2-dimensional polyacrylamide gel electrophoresis, mass spectrometry, multidimensional liquid chromatography, and bioinformatics. Mass spectrometry, which provides highly accurate molecular mass measurements, has emerged as the analytical technology of choice for protein identification, characterization, and sequencing. This task has been made considerably easier with the availability of complete, nonredundant, and annotated genome sequence databases for many organisms. This article reviews the area of expression proteomics.

Biotechnology↗
PubMed2005

[Beyond the genome to the proteome].

The sequence of the human genome has been decoded and a post-genome era is now beginning. This is the start of the protein/peptide era. Working in the fundamental research division of a pharmaceutical company and being engaged in studies on the research and development of new drugs based upon genomic information, it was clear to me that genomic information was useful, significant and indispensable in driving forward to new drug discovery. However, it is also true that we need more than that. I have faced multiple barriers in pursuing genomic information alone. There are numerous dead-end stories in genome-based new drug discovery and in many cases, those hurdles are very hard to get over. What approach can be a breakthrough of this bottleneck? I believe that one answer is research into proteins. The proteome describes all the proteins within an organism. The proteome analysis research field promises a bright future for the discovery of new drugs, diagnosis and therapeutics. I believe the mass spectrometer(MS) will be a key instrument in this research. The contribution of mass spectrometry was recently recognized in the Nobel Prize for Chemistry 2002, for 'the discovery of Soft Laser Desorption/Ionization' awarded to Mr. Koichi Tanaka. There is no doubt that the MS will play an essential role in accelerating proteome analysis. However, the present proteome analysis technology has not yet reached a sufficient scientific level. Further improvements of both hardware and software are necessary. For the hardware, improvements in sensitivity, accuracy and high-throughput, in addition to equipment for ultra-micro analysis applied to the analysis of the proteome should be addressed. Regarding software, we need to develop new chemistries for proteome analyses and propose original, user-friendly proteome analysis methods. In this review, starting with a briefing on genome-based drug discovery, I will discuss a new concept for proteome analysis based on mass spectrometry and new methodologies. This 'next generation' platform may provide a solution for the development of an integrated system that will contribute to our understanding of clinical information/bioinformatics, therapeutics, diagnosis and even drug discovery.

Amides↗