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Competitive Binding of Bilirubin and Fatty Acid on Serum Albumin Affects Wear of UHMWPE
Total Joint Replacement (TJR) devices undergo standardized wear testing in mechanical simulators while submerged in a proteinaceous testing solution to mimic the environmental conditions of artificial joints in the human body. Typically, bovine calf serum is used to provide the required protein cont...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7351145/ https://www.ncbi.nlm.nih.gov/pubmed/32655922 http://dx.doi.org/10.3390/lubricants8050053 |
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author | Fullam, Spencer He, Jade Scholl, Caroline S. Schmid, Thomas M. Wimmer, Markus A. |
author_facet | Fullam, Spencer He, Jade Scholl, Caroline S. Schmid, Thomas M. Wimmer, Markus A. |
author_sort | Fullam, Spencer |
collection | PubMed |
description | Total Joint Replacement (TJR) devices undergo standardized wear testing in mechanical simulators while submerged in a proteinaceous testing solution to mimic the environmental conditions of artificial joints in the human body. Typically, bovine calf serum is used to provide the required protein content. However, due to lot-to-lot variability, an undesirable variance in testing outcome is observed. Based on an earlier finding that yellowish-orange serum color saturation is associated with wear rate, we examined potential sources of this variability, by running a comparative wear test with bilirubin; hemin; and a fatty acid, oleic acid, in the lubricant. All these compounds readily bind to albumin, the most abundant protein in bovine serum. Ultrahigh molecular weight polyethylene (UHMWPE) pins were articulated against CoCrMo discs in a pin-on-disc tribometer, and the UHMWPE wear rates were compared between lubricants. We found that the addition of bilirubin increased wear by 121%, while hemin had a much weaker, insignificant effect. When added at the same molar ratio as bilirubin, the fatty acid tended to reduce wear. Additionally, there was a significant interaction with respect to bilirubin and hemin in that UHMWPE wear rate decreased with increasing fatty acid concentration. We believe the conformational change in albumin by binding bilirubin makes it more likely to form molecular bridges between UHMWPE and the metal counterface, thus increasing adhesive wear. However, fatty acids compete for binding sites on albumin, and can prevent this conformational change. Hence, the protein is stabilized, and the chance for albumin to form bridges is lowered. Ultimately, UHMWPE wear rate is driven by the competitive binding of bilirubin and fatty acid to albumin. |
format | Online Article Text |
id | pubmed-7351145 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
record_format | MEDLINE/PubMed |
spelling | pubmed-73511452020-07-10 Competitive Binding of Bilirubin and Fatty Acid on Serum Albumin Affects Wear of UHMWPE Fullam, Spencer He, Jade Scholl, Caroline S. Schmid, Thomas M. Wimmer, Markus A. Lubricants Article Total Joint Replacement (TJR) devices undergo standardized wear testing in mechanical simulators while submerged in a proteinaceous testing solution to mimic the environmental conditions of artificial joints in the human body. Typically, bovine calf serum is used to provide the required protein content. However, due to lot-to-lot variability, an undesirable variance in testing outcome is observed. Based on an earlier finding that yellowish-orange serum color saturation is associated with wear rate, we examined potential sources of this variability, by running a comparative wear test with bilirubin; hemin; and a fatty acid, oleic acid, in the lubricant. All these compounds readily bind to albumin, the most abundant protein in bovine serum. Ultrahigh molecular weight polyethylene (UHMWPE) pins were articulated against CoCrMo discs in a pin-on-disc tribometer, and the UHMWPE wear rates were compared between lubricants. We found that the addition of bilirubin increased wear by 121%, while hemin had a much weaker, insignificant effect. When added at the same molar ratio as bilirubin, the fatty acid tended to reduce wear. Additionally, there was a significant interaction with respect to bilirubin and hemin in that UHMWPE wear rate decreased with increasing fatty acid concentration. We believe the conformational change in albumin by binding bilirubin makes it more likely to form molecular bridges between UHMWPE and the metal counterface, thus increasing adhesive wear. However, fatty acids compete for binding sites on albumin, and can prevent this conformational change. Hence, the protein is stabilized, and the chance for albumin to form bridges is lowered. Ultimately, UHMWPE wear rate is driven by the competitive binding of bilirubin and fatty acid to albumin. 2020-05-10 2020-05 /pmc/articles/PMC7351145/ /pubmed/32655922 http://dx.doi.org/10.3390/lubricants8050053 Text en Submitted for possible open access publication under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Fullam, Spencer He, Jade Scholl, Caroline S. Schmid, Thomas M. Wimmer, Markus A. Competitive Binding of Bilirubin and Fatty Acid on Serum Albumin Affects Wear of UHMWPE |
title | Competitive Binding of Bilirubin and Fatty Acid on Serum Albumin Affects Wear of UHMWPE |
title_full | Competitive Binding of Bilirubin and Fatty Acid on Serum Albumin Affects Wear of UHMWPE |
title_fullStr | Competitive Binding of Bilirubin and Fatty Acid on Serum Albumin Affects Wear of UHMWPE |
title_full_unstemmed | Competitive Binding of Bilirubin and Fatty Acid on Serum Albumin Affects Wear of UHMWPE |
title_short | Competitive Binding of Bilirubin and Fatty Acid on Serum Albumin Affects Wear of UHMWPE |
title_sort | competitive binding of bilirubin and fatty acid on serum albumin affects wear of uhmwpe |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7351145/ https://www.ncbi.nlm.nih.gov/pubmed/32655922 http://dx.doi.org/10.3390/lubricants8050053 |
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