Structural dynamics of a colloidal protein-mineral complex bestowing on calcium phosphate a high solubility in biological fluids

• Published in: Biointerphases Vol. 2; no. 1; pp. 16 - 20
• Main Authors: Heiss, A, Jahnen-Dechent, W, Endo, H, Schwahn, D
• Format: Journal Article
• Language: English
• Published: United States 01.03.2007
• ISSN: 1934-8630; 1559-4106
• DOI: 10.1116/1.2714924

The concentration of mineral solutes in mammalian blood is considerably higher than that predicted by their solubility product. The plasma protein fetuin-A inhibits calcium phosphate deposition by forming colloidal calciprotein particles (CPPs). In this article the authors present a detailed small angle neutron scattering study including contrast variation analysis providing detailed quantitative information on the three-dimensional topology of the CPPs and on their morphogenesis. In detail the authors found the following: (i) A two stage growth process showing spontaneously formed primary particles with a size of about 500 A diameter that subsequently transformed to 1000 A sized particles which were stable for at least 24 h. (ii) A particular shielding topology was observed for the second CPP state, namely, that a densely packed fetuin-A monolayer covers a mineral core and thereby prevents further crystal growth. (iii) Transmission electron microscopy analysis of in vitro synthesized second state CPPs revealed striking similarities to material retrieved from a human peritonitis patient. This latter finding underscores the importance of short- and long-term stabilizations of CPPs by fetuin-A to enable clearing of mineral debris in the body.