Biological fluids such as plasma contain a high concentration of serum albumin making the detection of medium and low abundance proteins extremely challenging. A method of overcoming this obstacle is the use of Proteominer beads which are a novel sample preparation tool used for the compression of the dynamic range of protein concentration in complex biological samples. The beads comprise a mixed library of combinatorial peptide ligands. High abundance proteins saturate their high-affinity ligands and excess protein can be washed away. In contrast, lower abundant proteins are concentrated on their specific affinity ligands which reduces the dynamic range of protein concentrations while increasing the representation of proteins from the original sample.
This technique was applied to the analysis of synovial fluid from the joints of horses with particular conditions such as osteochondrosis, osteoarthritis and synovial sepsis compared with healthy control samples. The protein dynamic range of the synovial fluid was reduced using proteominer beads and following digestion with trypsin, LC-MSMS on a QExactive HF was carried out. Label-free quantification using Progenesis software-enabled comparison of differentially expressed between the 4 biological groups.
The study in conjunction with the Institute of Life Course and Medical Sciences, University of Liverpool, identified that equine synovial fluid proteome exhibits distinctive profile changes between osteoarthritis, osteochondrosis, synovial sepsis and healthy joints. These protein markers may have a future role in clinical practice to enable earlier and reliable diagnosis of synovial sepsis.
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