Gelli Rita, Martini Francesca, Geppi Marco, Borsacchi Silvia, Ridi Francesca, Baglioni Piero
Department of Chemistry "Ugo Schiff" and CSGI, University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
Department of Chemistry and Industrial Chemistry, University of Pisa, via G. Moruzzi 13, Pisa 56124, Italy; Center for Instrument Sharing of the University of Pisa (CISUP), Lungarno Pacinotti 43/44, 56126 Pisa, Italy.
J Colloid Interface Sci. 2021 Jul 15;594:802-811. doi: 10.1016/j.jcis.2021.03.062. Epub 2021 Mar 16.
It has been recently shown that, in our organism, the secretions of Ca, Mg and phosphate ions lead to the precipitation of amorphous magnesium-calcium phosphate nanoparticles (AMCPs) in the small intestine, where the glycoprotein mucin is one of the most abundant proteins, being the main component of the mucus hydrogel layer covering gut epithelium. Since AMCPs precipitate in vivo in a mucin-rich environment, we aim at studying the effect of this glycoprotein on the formation and features of endogenous-like AMCPs.
AMCPs were synthesized from aqueous solution in the presence of different concentrations of mucin, and the obtained particles were characterised in terms of crystallinity, composition and morphology. Solid State NMR investigation was also performed in order to assess the interplay between mucin and AMCPs at a sub-nanometric level.
Results show that AMCPs form in the presence of mucin and the glycoprotein is efficiently incorporated in the amorphous particles. NMR indicates the existence of interactions between AMCPs and mucin, revealing how AMCPs in mucin-hybrid nanoparticles affect the features of both proteic and oligosaccharidic portions of the glycoprotein. Considering that the primary function of mucin is the protection of the intestine from pathogens, we speculate that the nature of the interaction between AMCPs and mucin described in the present work might be relevant to the immune system, suggesting a novel type of scenario which could be investigated by combining physico-chemical and biomedical approaches.
最近的研究表明，在我们的机体中，钙、镁和磷酸根离子的分泌会导致小肠中无定形磷酸镁钙纳米颗粒（AMCPs）沉淀，而糖蛋白粘蛋白是小肠中含量最丰富的蛋白质之一，是覆盖肠道上皮的粘液水凝胶层的主要成分。由于AMCPs在富含粘蛋白的环境中在体内沉淀，我们旨在研究这种糖蛋白对类内源性AMCPs形成和特性的影响。
在不同浓度的粘蛋白存在下，从水溶液中合成AMCPs，并对所得颗粒的结晶度、组成和形态进行表征。还进行了固态核磁共振研究，以评估粘蛋白和AMCPs在亚纳米水平上的相互作用。
结果表明，在粘蛋白存在的情况下形成了AMCPs，并且该糖蛋白有效地掺入了无定形颗粒中。核磁共振表明AMCPs和粘蛋白之间存在相互作用，揭示了粘蛋白-杂化纳米颗粒中的AMCPs如何影响糖蛋白的蛋白质部分和寡糖部分的特性。考虑到粘蛋白的主要功能是保护肠道免受病原体侵害，我们推测本研究中描述的AMCPs与粘蛋白之间相互作用的性质可能与免疫系统相关，这表明了一种新型的情况，可以通过结合物理化学和生物医学方法进行研究。
