In vitro albumin binding on apatite crystals from developing enamel

Area of Science:

• Biomineralization
• Dental Research
• Materials Science

Background:

• Serum proteins are found in dentin and bone, bound to apatite.
• Enamel's unique organic/crystal structure was thought to prevent protein binding.
• Previous studies lacked direct evidence on enamel crystal protein interactions.

Purpose of the Study:

• To investigate the in vitro ability of enamel crystals to bind serum albumin.
• To determine if enamel crystallites possess free binding sites for serum proteins.
• To re-evaluate the reasons for the absence of blood proteins in mature enamel.

Main Methods:

• Isolation of crystals from developing bovine enamel.
• In vitro binding assays using gold-labelled serum albumin.
• Transmission Electron Microscopy (TEM) to observe crystal structure.

Main Results:

• Bovine developing enamel crystals, despite being coated with enamelins, demonstrated the ability to bind serum albumin.
• The binding of labelled serum albumin indicates the presence of accessible free binding sites on the enamel crystal surface.
• TEM observations of a 'sheath' around crystals may represent a dynamic binding process in vivo.

Conclusions:

• Enamel crystallites possess the capacity to bind serum proteins.
• The lack of serum proteins in enamel is not attributable to inherent properties of the enamel crystallites.
• A dynamic process in vivo may influence protein presence in enamel.