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Stable isotope labeling by amino acids in cell culture (SILAC) is a powerful method to study the relative proteomic change under differential treatments, which relies on the mass spectrometry and the metabolic incorporation of amino acids with substituted stable isotopic nuclei. In SILAC, a given 'light' or 'heavy' form of the amino acid is incorporated into two samples. Two cell populations are grown in culture media that are identical except that one of them contains a 'light' and the other contains a 'heavy' form of a particular amino acid (e.g. 12C and 13C labeled L-lysine, respectively). As the two isotopically labeled amino acids are essentially chemically identical, their incorporation does not interfere with normal cell growth, while leading to proteins/peptides that are distinguishable by mass and thus are ideal for mass spectrometric analysis. SILAC approaches are well suited for monitoring changes in post-translational modifications. https://www.creative-proteomics.com/services/silac-based-proteomics-analysis-2.htm

Proteomics research involves the identification and characterization of proteins to elucidate their function and interactions with other proteins. Since the composition of protein mixtures may vary across different cell types and may change under certain physiological conditions, one of the goals is often to quantify the up- or down-regulation of individual proteins. Shotgun proteomics approaches enable identification of proteins that are up-regulated or down-regulated under specific conditions and this can be studied in different cell and tissue lysates. Isobaric tags for relative and absolute quantification (iTRAQ) make it possible to both identify and quantify proteins simultaneously. iTRAQ can easily be multiplexed, enabling analysis of up to 8 different samples within the same experiment,that allows for high-throughput quantitative proteomics analysis. https://www.creative-proteomics.com/services/itraq-based-proteomics-analysis.htm

Proteins, biomolecules or macromolecules, perform a wide range of functions in organisms. Almost all of the cellular processes require that proteins specifically recognize a multitude of different interaction partners. They can carry out their roles by interacting with other molecules, including DNA, RNA, proteins and small molecules. Protein and protein interactions (PPIs), which refers to intentional physical contacts established between two or more proteins as a result of biochemical events and/or electrostatic forces. More can be reached at https://www.creative-proteomics.com/services/protein-protein-interaction-networks.htm

Creative Proteomics has established a highly sensitive HPLC-MS/MS pipeline that can analyze multiple kinds of phosphorylation in both eukaryotic and prokaryotic organisms. In addition, we have optimized our protocol, enabling more fast and sensitive site mapping service for histidine and tyrosine phosphorylation. https://www.creative-proteomics.com/services/phosphorylation.htm

Acetylation is an important modification of proteins in cell biology. N-acetylation, or the transfer of an acetyl group to nitrogen, occurs in almost all eukaryotic proteins through both irreversible and reversible mechanisms. N-terminal acetylation requires the cleavage of the N-terminal methionine by methionine aminopeptidase (MAP) before replacing the amino acid with an acetyl group from acetyl-CoA by N-acetyltransferase (NAT) enzymes. It occurs as a co-translational and post-translational modification of proteins, for example, histones, STAT, and microtubules...https://www.creative-proteomics.com/services/n-acetylation.htm

PTMs refer to the covalent and generally enzymatic modification of proteins during or after protein biosynthesis. It denotes changes in the polypeptide chain as a result of adding distinct chemical moieties to amino acid residues. PTMs are the foundation of governing intricate cellular process, such as cell division, growth, differentiation, signaling and regulation. Also, PTMs are involved in many cellular processes including the maintenance of protein structure and integrity, regulation of metabolism & defense processes, cellular recognition and morphology alternation. Consequently, analysis of protein post-translational modifications, including the modification categories and modified sites, is particularly crucial for the study of cell biology and disease diagnostics and prevention. More information about strategies for post-translational modifications (PTMs) can be reached at Creative Proteomics: https://www.creative-proteomics.com/services/protein-post-translational-modification-analysis.htm

Up to now, scientists suggested that human proteome presents significantly more complexity than the human genome. While the genome comprises 20,000-25,000 genes, the proteome is estimated at over 1 million proteins. The increase in proteomic diversity is further increased by protein post-translational modifications (PTMs). PTMs refer to the covalent and generally enzymatic modification of proteins during or after protein biosynthesis. It denotes changes in the polypeptide chain as a result of adding distinct chemical moieties to amino acid residues. PTMs are the foundation of governing intricate cellular process, such as cell division, growth, differentiation, signaling and regulation. Also, PTMs are involved in many cellular processes including the maintenance of protein structure and integrity, regulation of metabolism & defense processes, cellular recognition and morphology alternation. Consequently, analysis of protein post-translational modifications, including the modification categories and modified sites, is particularly crucial for the study of cell biology and disease diagnostics and prevention.More information about PTM can be reached at Creative Proteomics: https://www.creative-proteomics.com/services/protein-post-translational-modification-analysis.htm

Membrane proteins are a class of proteins that interact with or are part of, biological membranes. Membrane proteins can be classified into three parts based on their location and interactions with membranes: integral (membrane penetrating); peripheral (attached via non-covalent bonds); or lipid-anchored (attached through covalent bonds). Learn more at Creative Proteomics: https://www.creative-proteomics.com/services/protein-identification.htm

De novo sequencing is a process in which amino acid sequences are directly interpreted from tandem mass spectra without the assistance of a database. https://www.creative-proteomics.com/services/de-novo-peptides-proteins-sequencing-service.htm

Edman degradation, which was developed by Pehr Edman, is a method to sequence amino acids in a peptide. It is the Cyclic degradation of peptides based on the reaction of phenylisothiocyanate with the free amino group of the N-terminal residue. In this method, the amino-terminal residue is labeled and cleaved from the peptide without disrupting the peptide bonds between other amino acid residues. The Edman degradation reaction was automated in 1967 by Edman and Beggs to speed up the process. Now, automated Edman sequencers are widely use, and it can sequence peptides up to approximately 50 amino acids. https://www.creative-proteomics.com/

Peptide Mass Fingerprinting Peptide Mass Fingerprinting (PMF), also known as mass fingerprinting, was developed in 1993. It is a high throughput protein identification technique in which the mass of an unknown protein can be determined. PMF is always performed with Matrix-assisted laser/desorption ionization-time of flight (MALDI-TOF) mass spectrometry. https://www.creative-proteomics.com/resource/the-principle-characteristics-and-application-of-peptide-mass-fingerprinting.htm

Label-free protein quantification is a mass spectrometry-based method for identifying and quantifying relative changes in two or more biological samples instead of using a stable isotope-containing compound to label proteins. https://www.creative-proteomics.com/services/itraq-based-proteomics-analysis.htm

iTRAQ is an acronym of Isobaric tag for relative and absolute quantitation, which was developed by Applied Biosystems Incorporation in 2004. It is an isobaric labeling method to determine the amount of proteins from different sources in just one single experiment by mass spectrometry. https://www.creative-proteomics.com/services/itraq-based-proteomics-analysis.htm

Under physiological condition, most protein-protein interactions are transient, and happen in a very short duration, which make them difficult to be studied. Crosslinking reagents, or crosslinkers, provide the analytical solution to capture protein-protein complexes by covalently binding them together as they interact, to freeze even transient, weak interactions for consequent isolation and characterization. https://www.creative-proteomics.com/services/crosslinking-protein-interaction-analysis.htm

Mass Spectrometry-Mass Analyzer at Creative Proteomics. https://www.creative-proteomics.com/

Two dimensional polyacrylamide gel electrophoresis at Creative Proteomics. https://www.creative-proteomics.com/

The transfer or "blotting" of electrophoretic separated proteins from the gel matrix to a membrane (typically nitrocellulose or PVDF) followed by subsequent antibody-based detection on the surface of the membrane is called Western Blot or Immunoblot. Creative Proteomics provides western blotting analysis for the detection of a specific target protein out of a complex protein mixture, e. g. tissue homogenate or cell extract, using highly selective and sensitive antibody-antigen interactions. The resulting data allow both qualitative and semi-quantitative analysis of the protein of interest. https://www.creative-proteomics.com/services/western-blot-electrical-transfer.htm

Proteomics is a large-scale comprehensive study of a specific proteome, including information on protein abundances, the variations and modifications, as well as their interacting partners and networks. In discovery proteomics, proteome analysis can be performed in two different strategies, bottom-up and top-down approaches, respectively. In the bottom-up approach, a crude protein mixture undergoes protease digestion first, and then separation by liquid chromatography, followed by MS analysis. In the top-down method, proteins are characterized by MS without prior proteolysis. This type of approach has the advantage of providing greater sequence coverage, resolution of sequence ambiguities and preservation of PTMs. https://www.creative-proteomics.com/services/proteomics-service.htm

Glycans are defined as the compounds that consist of a large number of monosaccharides linked glycosidically. Glycans have diverse biological functions and it can be classified into two broad categories. One is the structural and modulatory properties of glycans and the other is the specific recognition of glycans by other molecules, most commonly, glycan-binding proteins (GBPs). The GBPs can be divided into two types, intrinsic GBPs and extrinsic GBPs.

Glycomics, the study of glycans, is applied to biology and chemistry that focuses on the structure and function of carbohydrates, and on glycoform distributions at the cellular, tissue, organ and organism levels. https://www.creative-proteomics.com/

Proteomics studies play an increasing role in the field of biology. The use of mass spectrometry (MS) in combination with a range of separation methods is the main principal methodology for proteomics. The two principal approaches to identifying and characterizing proteins using MS are the “bottom-up”, which analyze peptides by proteolytic digestion, and “top-down”, which analyze intact proteins. https://www.creative-proteomics.com/

If you want to learn more about PPI methods at Creative Proteomics, more can be reached at https://www.creative-proteomics.com/