MALDI-TOF
MALDI-TOF
MALDI-TOF, or Matrix-Assisted Laser Desorption/Ionization Time-of-Flight, is a sophisticated analytical technique used primarily in the field of mass spectrometry to analyze biomolecules, such as proteins, peptides, and other large organic molecules. This method is renowned for its ability to ionize large molecules without fragmentation, making it an invaluable tool in proteomics, microbiology, and biochemistry.
Principle of MALDI-TOF[edit | edit source]
MALDI-TOF mass spectrometry involves two main processes: the ionization of the sample and the measurement of the time-of-flight of the ions.
Ionization[edit | edit source]
In MALDI, the sample is mixed with a matrix, a small organic compound that absorbs laser energy. The matrix and sample are co-crystallized on a target plate. When a laser pulse is directed at the sample, the matrix absorbs the energy and facilitates the desorption and ionization of the sample molecules. This process results in the formation of singly charged ions, which are then accelerated into the time-of-flight analyzer.
Time-of-Flight Analysis[edit | edit source]
The ions generated are accelerated by an electric field into a flight tube. The time it takes for each ion to reach the detector at the end of the tube is measured. Since the time-of-flight is dependent on the mass-to-charge ratio (m/z) of the ions, this allows for the determination of the molecular weight of the analytes. Lighter ions reach the detector faster than heavier ones, enabling the separation and identification of different molecules based on their mass.
Applications of MALDI-TOF[edit | edit source]
MALDI-TOF is widely used in various scientific fields due to its versatility and high-throughput capabilities.
Proteomics[edit | edit source]
In proteomics, MALDI-TOF is used for protein identification and characterization. It is particularly useful in the analysis of complex protein mixtures and post-translational modifications.
Microbiology[edit | edit source]
MALDI-TOF has revolutionized the field of clinical microbiology by enabling rapid identification of bacteria and fungi. It is used in clinical laboratories to identify pathogens directly from patient samples, significantly reducing the time required for diagnosis.
Biochemistry[edit | edit source]
In biochemistry, MALDI-TOF is employed to study enzyme activities, protein-protein interactions, and the structure of biomolecules.
Advantages of MALDI-TOF[edit | edit source]
- High Sensitivity: Capable of detecting low concentrations of analytes. - Speed: Rapid analysis with minimal sample preparation. - Versatility: Applicable to a wide range of biomolecules. - Minimal Fragmentation: Preserves the integrity of large biomolecules during ionization.
Limitations of MALDI-TOF[edit | edit source]
- Matrix Interference: The choice of matrix can affect the ionization efficiency and result in background noise. - Limited Quantitative Analysis: While qualitative analysis is robust, quantitative analysis can be challenging.
Also see[edit | edit source]
- Mass Spectrometry - Proteomics - Clinical Microbiology - Biochemistry
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Contributors: Prab R. Tumpati, MD