Sherratt Michael J, Baldock Clair, Morgan Amanda, Kielty Cay M
Division of Regenerative Medicine, Faculty of Medical and Human Sciences, The Medical School, Stopford Building, The University of Manchester, Oxford Road, Manchester, UK.
Matrix Biol. 2007 Apr;26(3):156-66. doi: 10.1016/j.matbio.2006.10.015. Epub 2006 Nov 7.
The adsorption of proteins to surfaces may alter their biological properties. Understanding and controlling these interactions is important in ultrastructural, biochemical and cellular studies. We have previously demonstrated that both the morphology and biological function of extracellular matrix assemblies such as fibrillin and type VI collagen microfibrils are influenced by surface chemistry. In this study we have employed atomic force microscopy to determine if the morphology of extracellular matrix microfibrils is influenced by solution chemistry. Microfibrils were adsorbed to mica or poly-L-lysine modified mica (mica-PLL) in the presence of 31 microM-1000 microM Ca(2+). Although both microfibrillar species adsorbed to mica and mica-PLL at all calcium concentrations, maximal adsorption was observed on mica at 125-250 microM. On mica surfaces fibrillin microfibril morphology varied continuously with calcium concentration from laterally diffuse assemblies at high concentrations to compact assemblies at low concentrations. In contrast, distinct type VI collagen microfibril morphologies were observed at high, intermediate and low calcium concentrations. Similar calcium dependent microfibrillar morphologies were evident on mica-PLL. Therefore physiologically relevant concentrations of solution calcium, independent of surface charge, profoundly influenced both the adsorbed amount and morphology of native extracellular assemblies. These studies highlight the importance not only of surface chemistry but also of solute composition and concentration in influencing the morphology and hence biological function of adsorbed proteins.
蛋白质在表面的吸附可能会改变其生物学特性。在超微结构、生物化学和细胞研究中，理解和控制这些相互作用非常重要。我们之前已经证明，细胞外基质组装体（如原纤蛋白和VI型胶原微原纤维）的形态和生物学功能会受到表面化学的影响。在本研究中，我们采用原子力显微镜来确定细胞外基质微原纤维的形态是否受溶液化学的影响。在存在31微摩尔至1000微摩尔钙离子的情况下，将微原纤维吸附到云母或聚-L-赖氨酸修饰的云母（云母-PLL）上。尽管在所有钙浓度下，两种微原纤维种类都能吸附到云母和云母-PLL上，但在125-250微摩尔时，在云母上观察到最大吸附量。在云母表面，原纤蛋白微原纤维的形态随钙浓度不断变化，从高浓度下的横向弥散组装体到低浓度下的紧密组装体。相比之下，在高、中、低钙浓度下观察到了不同的VI型胶原微原纤维形态。在云母-PLL上也明显出现了类似的钙依赖性微原纤维形态。因此，生理相关浓度的溶液钙，与表面电荷无关，深刻影响了天然细胞外组装体的吸附量和形态。这些研究不仅突出了表面化学的重要性，还强调了溶质组成和浓度在影响吸附蛋白质的形态以及生物学功能方面的重要性。
