In the realm of proteomics, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS/MS) represents a groundbreaking technical development. This advanced analytical method has several uses, including accurate protein identification and quantification, comprehensive evaluation of post-translational modifications, and explanation of complex protein-protein interactions. Due to its outstanding sensitivity, rapid analysis, and remarkable adaptability, MALDI-MS/MS has solidified its position as a vital tool for scientists who are committed to understanding the proteome's complexity. In the MALDI-MS, the sample is combined with a matrix and then exposed to a laser to generate ions for mass analysis.
Table 1. Various Application of Organic Matrices in MALDI-MS. (Darie-Ion L, et al. 2022)
| Matrix |
Application |
| ɑ-cyano-4-hydroxycinnamic acid (CHCA) |
small molecules, peptides/proteins < 6 kDa |
| 2,5-dihydroxybenzoic acid (DHB) |
small molecules, peptides/proteins < 6 kDa, polymers, carbohydrates |
| α-cyano-5-phenyl-2,4-pentadienic acid (CPPA) |
proteins |
| 3,5-dimethoxy-4-hydroxycinnamic acid (SA, sinapinic acid) |
proteins |
| 2-(4-Hydroxyphenylazo)benzoic acid (HABA) |
peptides, proteins, glycoproteins |
| 9-aminoacridine (9-AA) |
small molecules, lipids, MALDI (−) |
By using MALDI-MS/MS, this technique is enhanced. It combines tandem mass spectrometry with MALDI-MS to provide a greater understanding of the structure and function of proteins. A precursor ion is chosen from the first MALDI-MS analysis, broken up into smaller ions, and then sent through a second round of mass spectrometry in MALDI-MS/MS. Scientists may investigate post-translational modifications, protein-protein interactions, and other areas of study because of this fragmentation, which gives vital information on the protein's sequence and structure.
Fig 1. General representation of the desorption/ionization principle in MALDI-MS. (Darie-Ion L, et al. 2022)
Quantitative Proteomics
MALDI-MS/MS methods such as isotope labeling and label-free quantification make quantitative proteomics possible. It allows scientists to determine the relative amounts of proteins in different conditions, offering insights into dynamic cellular processes.
Structural Proteomics
The study of protein structures is paramount in unraveling their functional intricacies. In this regard, MALDI-MS/MS plays a pivotal role by furnishing comprehensive insights into protein folding, conformation, and stability.
Clinical Applications
MALDI-MS/MS has made substantial inroads into the clinical domain, where it finds utility in both biomarker discovery and diagnostics. This cutting-edge technology facilitates the precise identification of potential disease markers present in various bodily fluids. As a result, it plays a pivotal role in advancing the field of early disease detection and the subsequent tailoring of personalized medical interventions.
Challenges
Although proteomics research has greatly improved thanks to MALDI-MS/MS, there are still certain difficulties. The intricacies involved in sample preparation, instrument operation, and data analysis can be quite complex, demanding a high level of expertise. Furthermore, the identification of novel proteins or those with unique modifications is often constrained by the limitations of existing databases.
Reference
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Darie-Ion L, Whitham D, Jayathirtha M, Rai Y, Neagu AN, Darie CC, Petre BA. Applications of MALDI-MS/MS-Based Proteomics in Biomedical Research. Molecules. 2022; 27(19):6196.
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