Effect of the Myeloperoxidase Enzyme on Protein Tissue Oxidation and Its Possible Implications in the Pathology of Rheumatoid Arthritis

Savannah L. Kile, Dr. Kathryn Matera, Department of Chemistry, Elon University, 100 Campus Drive, 27244

Numerous research studies have established a correlation between rheumatoid arthritis (RA) and a high level of the oxidative enzyme myeloperoxidase (MPO) in synovial fluid of patients' inflamed joints. Additionally, extracellular MPO has been found locally among necrotic tissue in the joints; this tissue, composed mostly of collagen, has oxidative damage.  Therefore, it is likely that MPO is part of RA pathology; however, its exact role is still unclear.  Binding studies were conducted to initially examine the potential binding interactions between MPO and collagen. To do this, specific amino acids found in collagen, including hydroxyproline (polar), proline (nonpolar), and phenylalanine (nonpolar, aromatic), were used in these binding studies; binding was measured by observing changes in the UV-Vis spectrum of peroxidase both in the presence and absence of amino acids. For the MPO binding study, proline (KD=0.054mM) had a higher binding affinity to MPO compared to phenylalanine (KD=0.072mM) and hydroxyproline (KD=0.94mM). After it was determined that MPO interacted with the amino acids, enzyme kinetics were conducted to determine if MPO oxidizes collagen and the amino acid hydroxyproline specifically, which has an oxidizable hydroxy functional group. Preliminary studies using UV-Vis spectroscopy suggest that MPO does readily oxidize both compounds. Additionally, this study was used to determine if an SDS-PAGE could be used to qualitatively determine if collagen had been oxidized in the presence of MPO. Preliminary results using SDS-PAGE have shown visibly different banding patterns between unoxidized and oxidized collagen samples; therefore, it was determined that this method could be used to qualitatively determine if collagen has been oxidized.  These results suggest that MPO contributes to the oxidation of collagen, which is a key mechanism within the pathology of RA.

Additional Abstract Information

Presenter: Savannah Kile

Institution: Elon University

Type: Poster

Subject: Biochemistry

Status: Approved

Time and Location

Session: Poster 1
Date/Time: Mon 1:30pm-2:30pm
Session Number: 2113