Fig. 5

In vitro mineralization activity of recombinant enamelin. (A) The curves show turbidity over time as a measure for calcium phosphate precipitation. Mineralization buffer containing enamelin at 0.5 mg/ml (CaP + enamelin) is compared to buffer alone (CaP). Non-mineralizing buffer without (P) and with enamelin (P + enamelin) were used as negative controls. Three separate experiments were carried out, and the values plotted are the mean values and the error bars indicate the standard error of the mean. (B) SDS-PAGE analysis of samples taken during mineralization experiment with enamelin in combination with calcium- and phosphate ions (Ca, P, CaP). Soluble (sup) and insoluble (pellet) samples are taken after centrifugation of the complete sample (total). The enamelin band is not present in any of the pellet samples, suggesting that the protein is soluble during the mineralization assay. (C) FTIR spectra of the CaP mineralization sample with and without enamelin. Bands expected in calcium phosphate mineral can be observed and associated to OH (3533-3469-3255–3151 cm^− 1), PO (1116-1046-980 cm^− 1) and mineral bound H₂O (1644 cm^− 1), indicating presence of brushite [25,26,27]