Department of Chemical & Biological Engineering, University of Idaho, Moscow, ID, USA.
Biotechnol Appl Biochem. 2022 Apr;69(2):492-502. doi: 10.1002/bab.2126. Epub 2021 Mar 17.
Serum albumin is the most prominent protein in blood, and it aids in bone fracture healing, though the manner through which enhanced healing occurs is not well understood. This study investigates the influence of calcium on the bioactivity of albumin due to the prevalence of calcium at bone injury sites. Bovine serum albumin (BSA) was exposed to varying concentrations of calcium, adsorbed to tissue culture polystyrene, and the subsequent BSA-coated surfaces were evaluated with calcium titration, and cell adhesion, viability, and binding inhibition studies. Calcium-modified BSA improved overall MC3T3-E1 osteoblast-like cell adhesion, although high calcium concentrations induced cell death. Inhibiting specific integrins revealed that without calcium exposure, cell binding to BSA was primarily mediated by integrins that typically bind to the GFOGER sequence of collagen. As calcium exposure increases, the primary binding interaction transitioned to integrins known to bind RGD. However, cell binding to calcium-modified BSA was not completely eliminated during the inhibition studies indicating additional unidentified binding interactions occur. Overall, these results suggest that the exposure to calcium induces conformational changes that affect the cell-binding bioactivity of BSA, which may explain the beneficial impact of albumin in bone tissue.
血清白蛋白是血液中最主要的蛋白质，它有助于骨折愈合，尽管增强愈合的方式还不太清楚。本研究调查了钙对白蛋白生物活性的影响，因为钙在骨损伤部位很常见。牛血清白蛋白（BSA）暴露于不同浓度的钙中，吸附到组织培养聚苯乙烯上，随后用钙滴定、细胞黏附和结合抑制研究来评估随后的 BSA 涂层表面。钙修饰的 BSA 提高了 MC3T3-E1 成骨样细胞的整体黏附性，尽管高浓度的钙会诱导细胞死亡。抑制特定整合素表明，在没有钙暴露的情况下，细胞与 BSA 的结合主要是由通常与胶原蛋白的 GFOGER 序列结合的整合素介导的。随着钙暴露的增加，主要的结合相互作用转变为已知与 RGD 结合的整合素。然而，在抑制研究中，钙修饰的 BSA 上的细胞结合并没有完全消除，这表明发生了其他未识别的结合相互作用。总的来说，这些结果表明，钙的暴露诱导了构象变化，从而影响了 BSA 的细胞结合生物活性，这可能解释了白蛋白在骨组织中的有益影响。
