Proteomic Analysis of Complex Protein Samples by MALDI–TOF Mass Spectrometry

Abstract

MALDI MS has become a technique of considerable impact on many fields, from proteomics to lipidomics, including polymer analysis and, more recently, even low molecular weight analytes due to the introduction of matrix-less ionization techniques (e.g., DIOS) or new matrices such as ionic liquids, proton sponges, and metal nanoparticles. However, protein identification by peptide mass fingerprint (PMF) still remains the main routine application. In the last few years, MALDI MS has played an emerging role in food chemistry especially in detection of food adulterations, characterization of food allergens, and investigation of protein structural modifications, induced by various industrial processes that could be detrimental for food quality and safety. Sample handling and pretreatment can be very different depending on the physical state, liquid or solid, of the analyzed matrices. Here, we describe simple protocols for protein extraction and MALDI MS analysis of liquid (milk) and solid (hazelnuts) samples taken as model. A classic approach based on a preliminary SDS gel electrophoresis separation followed by in-gel digestion and a faster approach based on in-solution digestion of whole samples are described and compared.

MALDI-TOF Mass Spectrometry Applications for Food Fraud Detection

“…[44] compared the principal proteins in bovine, caprine, buffalo, equine, and camel milk, finding interesting differences between the species that could be used to identify sources of hypoallergenic alternatives to bovine milk and detect adulteration of milk samples and derived products. A proteomic approach for the MALDI-TOF analysis of commercial bovine milk, based on in-solution digestion of the whole samples, was also suggested [45] for the routine analysis of raw and processed foods and to detect adulterations.…”

“…Sequenom ® MassARRAY ® (Agena Bioscience, San Diego, CA, USA) MALDI-TOF MS, a reliable platform for detection and validation of single nucleotide polymorphisms (SNPs) for varietal analysis, was used to target specific genes in order to genotype and differentiate 35 barley varieties [104]. Information was drawn from the majority (33) of the tested loci (45), permitting the generation of a unique barcode of SNPs for each barley cultivar. This reliable and fast approach can potentially identify more than 150,000 SNPs per day, making the platform a suitable alternative for cereal varieta identification.…”

Advanced Mass Spectrometry

“…MALDI-TOF Quality control of high protein content sport supplements [60] MALDI-TOF Proteomic analysis of complex protein sample [121] MALDI-TOF Identifying glycation inhibitors [122] Tanscriptomics MALDI-TOF Gene analysis using mass spectrometric cleaved amplified polymorphic sequence (MS-CAPS) [123] Microorganisms Identification…”