Analysis of Peptides & Proteins / MALDI & Q-TOF
Applications for MALDI & Q-TOF
Quality Control of Synthetic Peptides using the MALDI-8030 Dual Polarity Benchtop MALDI-TOF Mass Spectrometer
Synthetic peptides are nowadays increasingly used in the fields of biochemistry, immunology, and medicine. They fulfil several purposes, such as cancer diagnosis and treatment, drug and delivery systems development, epitope mapping, production of antibodies, and vaccine design. The synthesis of peptides is a stepwise process which involves a reaction between the activated carboxylic group of one amino acid and the amino group of another, thus creating the socalled peptide bond.
MALDI-TOF mass spectrometry is widely used to confirm the molecular identity of the final peptide as well as its purity. Here, we present the dual polarity MALDI-8030 benchtop linear mass spectrometer for the QC analysis of synthetic peptides in positive and negative ion modes. The benefits of the negative ionisation mode are demonstrated in terms of: i) preserving the integrity of species carrying labile functional groups; ii) simplifying the interpretation of the mass spectra through elimination of salt adduct interferences.
Quality Control Analysis of Synthetic Peptides Using the MALDI-8020 Benchtop Linear MALDI-TOF Mass Spectrometer and QC Reporter Software
Within the manufacturing process of bio-therapeutics, quality control (QC) plays a fundamental role in guaranteeing the supply of a high quality product. Any changes in the product formulation or degradation can affect the therapeutic role, leading to a potential loss of activity or development of toxicity. Amongst the several analytical techniques that can be used to determine the quality of a synthetic bio-product, MALDI-TOF mass spectrometry is widely employed due to its rapid and simple operation, low running costs, sensitivity and ability to provide information on the molecular weight as well as the sequence and structure of a compound, its impurities/adducts and modification products.
Protein Identification from Two-dimensional Gel Electrophoresis Based on Peptide Mass Fingerprinting (PMF) Using a Benchtop MALDI-TOF Mass Spectrometer
At present, shotgun proteomics techniques using liquid chromatography mass spectrometry are utilized mainly as high-throughput methods for identifying many different proteins in cellular cytoplasm. However, these techniques are not necessarily effective for identifying all proteins. In particular, when handling proteins separated by means of two-dimensional electrophoresis etc., the protein spots detected on the electrophoresis gel must be linked to the results of protein identification. For such analyses, there may be many cases where using MALDI-TOF mass spectrometry is more efficient than using liquid chromatography mass spectrometry after enzyme treating the protein spots separated from the gel. This article introduces an example of protein identification using two-dimensional electrophoresis and a benchtop MALDI-TOF mass spectrometer.
MALDI-MS Protein Profiling of Chemoresistance in Extracellular Vesicles of Cancer Cells
Faster detection of chemoresistance will improve cancer therapy and therefore improve cancer survival rates. Cancer cells communicate with the whole organism via extracellular vesicles (EVs), which circulate the body and propagate molecular information in support of the malignant phenotype. EVs were harvested from cell culture supernatant by ultracentrifugation to serve as a model for circulating cancer cell-derived biomarker carriers from body fluids (i.e., liquid biopsy). In this work, differential expression of proteins in EVs, measured by MALDI-TOF-MS, as the result of an increasing chemoresistance of their parent cells was observed.
Protein Sequence Analysis by In-Source Decay Using a Benchtop MALDI-TOF Mass Spectrometer
MALDI-TOF mass spectrometers are frequently used for molecular weight measurement and identification of proteins. To identify proteins using a mass spectrometer, generally tryptic digestion is required for preparation; however, if the protein is isolated and purified, by detecting the ions produced by fragmentation within an ion source (ISD, In-Source Decay), sequence analysis of intact proteins can be performed with no need to digest the protein with trypsin.