Protein and Proteome Analysis

Identification, characterization and expression analysis of proteins

Protein

Proteins, macromolecules made up of amino acids, are major building blocks of all cells. They shape the cells structure and as molecular “machines” are responsible, for example, for the transport of substances, the catalysis of chemical reactions and the recognition of signaling molecules. Amino acids, which are linked by peptide bonds to form chains of up to several thousand units, serve as building blocks. In this context, the sequence of amino acids determines the structure and function of the protein.

Proteins – Proteomics

The totality of all proteins in an organism, a tissue, a cell or a cell compartment under exactly defined conditions and at a specific point in time is termed proteome. As a result of continuous de novo synthesis and the concurrent degradation of proteins, its composition changes continuously. These changes are influenced by environmental stimuli and controlled by complex regulatory processes. Depending on the species, the proteome can comprise up to 1,000,000 protein species and thus normally exceeds the number of gene sequences encoded in the genome many times over. This is primarily the result of mRNA splicing and subsequent (posttranslational) modifications of the proteins.

Posttranslational protein modifications occur subsequent to translation. These changes are usually initiated by the organism or by the cells themselves and can be influenced by environmental factors. Examples of the multifarious possibilities are phosphorylation, which is mediated by protein kinases, hydroxylations of proline residues or glycosylations. Some of these processes occur at the protein synthesis site, others occur in certain organelles or also outside the cell.

Applications

Maldi Spotter

In the past decade, the importance of mass spectrometry for protein analyses has greatly increased. It can be used both to identify a protein and to analyze the amino acid sequence of a so far unknown protein. In the process, possible alterations in the side chains can be detected, such as those occurring in posttranslational modifications. In combination with different sample preparation procedures, mass spectrometry is an important tool in the repertoire of current methods for analyzing individual proteins or entire proteomes.

Protein and proteome analytics at Fraunhofer IGB

The techniques used for protein analytics at Fraunhofer IGB comprise gel electrophoretic, chromatographic and mass spectrometric methods, which can be used for a broad application spectrum:

  • Protein identification
  • Protein characterization – Posttranslational modifications
  • Expression analysis – Proteomics
  • Identification and validation of biomarkers
  • Quality control of expressed proteins