Biomass Spectrometry / MALDI-TOF
Biomass Spectrometry / MALDI-TOF
Biomass spectrometer, the ionization method is mainly electrospray ionization and matrix-assisted laser desorption ionization, the former often use quadrupole mass analyzer, the composition of the instrument known as electrospray (quadrupole) mass spectrometer (ESI-MS) , The latter commonly used flight time as a mass analyzer, the composition of the instrument known as matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). One of the features of ESI-MS is that it can be used in combination with modern separation methods such as liquid chromatography and capillary electrophoresis, which greatly expands its application in life sciences, including drug metabolism, clinical and forensic applications, etc. MALDI- TOF-MS is characterized by its high tolerance to salts and additives, as well as fast sample rate and easy handling. In addition, mass spectrometers useful for biological macromolecular assays include ion trap (IT) mass spectrometry and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry.
The newer types of mass spectrometers are the LC-ESI-MS-MS and the MALDI-TOF mass spectrometer with tandem mass spectrometry, the former of which is the traditional electro- Spray mass spectrometer based on the use of time-of-flight mass analyzer instead of quadrupole mass analyzer, greatly improving the instrument resolution, sensitivity and quality range; the latter is added to the mass spectrometry post-source decay (post-source decay, PSD) mode or collisionally induced dissociation (CID) mode, thereby making it possible to sequence biological macromolecules.
MALDI-TOF instrument composition and principle
MALDI-TOF-MS (Matrix Assisted Laser Desorption / Ionization Time of Flight Mass Spectrometry) is a new type of soft ionized bio mass spectrometer developed in recent years. Whether in theory The design is still very simple and efficient.
The instrument is mainly composed of two parts: matrix-assisted laser desorption ionization ion source (MALDI) and time of flight mass analyzer (TOF). The principle of MALDI is to use a laser to irradiate the co-crystal film formed by the sample and the substrate. The substrate absorbs energy from the laser and transfers it to the biomolecules. During ionization, protons are transferred to or from the biomolecules to ionize the biomolecules process. It is therefore a soft ionization technique for the determination of mixtures and biological macromolecules. The principle of TOF is that ions accelerate through the flight pipe under the action of an electric field and are detected according to the flight time reaching the detector. That is, the mass-to-charge ratio (M / Z) of the measured ions is proportional to the ion flight time, and ions are detected. MALDI-TOF-MS has the characteristics of high sensitivity, high accuracy and high resolution. It provides a powerful analytical test method for life sciences and other fields and is playing an increasingly important role.
MALDI-TOF role and characteristics
Molecular weight is the most basic physical and chemical properties of organic compounds parameters. Whether the molecular weight is correct or not often means that the structures of the organic compounds and biological macromolecules measured are correct or not. MALDI-TOF is a soft ionization technique that does not generate or generate fewer fragment ions. It can be directly applied to the analysis of the mixture can also be used to detect the sample contains impurities and impurities molecular weight. Molecular weight is also the primary parameter in the identification of biological macromolecules such as peptides and proteins. It is also one of the important data for approval of gene engineering products. The accuracy of MALDI-TOF is as high as 0.1% -0.01%, much higher than the currently used SDS electrophoresis and high performance gel chromatography.
Proteomics is the frontier field of current life science research. Rapid and accurate identification of proteins is an essential and crucial step in proteomics research. It is the most commonly used identification method in proteomics research to identify proteins by means of query and identification of the peptide mass fingerprint (PMF) measured by MALDI-TOF-MS. Peptide Mass Fingerprinting (PMF) is a mass map of a peptide fragment obtained by proteolytic cleavage of a protein at a specific enzyme cleavage site. Since the amino acid sequence (primary structure) of each protein is different, the sequence of peptide fragments produced when the protein is hydrolyzed also varies, and thus its peptide mass fingerprint is also characteristic. MALDI-TOF-MS analysis of peptide mixtures was able to tolerate the appropriate amount of buffers, salts, and almost all of the individual peptide fragments produced only singly charged ions, so MALDI-TOF was the preferred method for the analysis of PMF.
As the reliability of PMF identification results are affected by many factors, the results of partial identification are often not very clear, the specificity is not high. Polypeptide amino acid sequence matching is considered the best specificity of the identification method. In proteomics research, there are generally two ways of using MS sequencing: one is sequencing by tandem mass spectrometry (MS / MS); the other is sequencing by post-source decay (PSD).
In a reflective MALDI-TOF-MS, when pulsed laser light is applied to the cocrystals formed by the mixing of a small sample with a saturated small molecule matrix, energy is transferred to the sample through the matrix, causing the sample to be ionized and the metastable molecules formed after ionization Ions are cleaved when they fly through a field-free zone (ie, flight zone) (their activation energy comes from collision between ion source and substrate, collisions with residual gas in the absence of field, laser radiation and various thermal mechanisms, etc.) (Ie, source-fragment ions) can be separated by constantly changing the voltage of the reflector, collected and recorded in the detector to form a PSD mass spectrum that provides very rich and efficient structural information for the polypeptide and protein primary structures Figure The use of PSD spectra combined with database searches allows for the rapid and high-specificity identification of proteins.
At present, in the proteomics research, part of the protein samples separated by 2DE can not be identified by PMF or the identification results are not clear, and PSD sequencing can be applied to the identification of these proteins. With the continuous research and development of PSD technology, especially in combination with the high sensitivity and high throughput of MALDI-TOF-MS itself, the determination of sample targets can be performed many times. The analysis mainly produces single charge quasi-molecular ions and can Tolerance to a certain amount of salt and interference and other characteristics, PSD-MALDI-TOF-MS will play a greater role in the study of proteomics, metabolomics and drug screening.
In addition, with the development of molecular biology techniques and antisense nucleic acid drug technologies, more and more oligonucleotide fragments have been synthesized for use as primers, probes, antisense drugs and the like. It is absolutely essential that these fragments be rapidly tested to determine if the complete and synthetic sequences synthesized are correct. Biomass spectrometry, including MALDI-TOF-MS, is by far the best means of performing this assay. Analysis of oligonucleotides by MALDI-TOF-MS is simple, fast, accurate and sensitive. Combined with 3 'exonuclease and 5' exonuclease, the full oligonucleotide sequence can be determined.
Analytical instruments
Physical property test
Environmental monitoring and analysis
Lab general equipment
About us
About this website
Our service
Product purchase
Contact Us


Make Sure you dont miss interesting happenings by joining our newsletter program.

Contact Us