A 5 μl aliquot of plasma filtrate was mixed with 1 μl NuPAGE® reducing agent, buy PF-02341066 2.5 μl NuPAGE® sample buffer and 1.5 μl of water according to manufacturer’s instructions (Invitrogen Ltd, Paisley, UK). Any bubbles were removed and the samples were selleck denatured by heating for 15 min at 75 °C and then placing on ice for 10 min. The samples were then loaded onto NuPage® 4–12 % Bis-Tris gels (Invitrogen Ltd, Paisley, UK) and were separated at 200 V for 25 min. The proteins were then transferred onto a nitrocellulose membrane (Invitrogen Ltd, Paisley, UK) using the Xcell blot II Module (Invitrogen
Ltd, UK) for 1 h at 30 V using NuPAGE® transfer buffer (Invitrogen Ltd, Paisley, UK) according to manufacturer’s instructions. Membranes were incubated in blocking solution (5 % dry fat-free milk powder in phosphate buffered saline (PBS)–Tween solution (PBS with 0.1 % Tween-20; Sigma-Aldrich Company Ltd, Dorset,
UK) for 2 h at room temperature. Membranes were then incubated in the MM-102 primary antibody, anti-FGF23 polyclonal antibody that recognizes the C-terminal of FGF23, diluted 1:1,000 with the blocking solution for 1 h at room temperature. Membranes were then washed with PBS-Tween and then incubated with the secondary antibody, donkey polyclonal antibody to Goat IgG conjugated to HRP (Abcam, Cambridge, UK), diluted 1:2,000 in the blocking solution Dichloromethane dehalogenase for 30 min at room temperature. Membranes were then washed with PBS-Tween and incubated with the
substrate (Amersham ECL Plus Western Blotting Detection System; GE Healthcare Life Sciences, UK) for a short time before being exposed to a CCD camera (Alpha Innotech Imager) to capture the resulting chemiluminescent signal. Protein staining After SDS-PAGE, the gels were stained using the Colloidal Blue Staining Kit (Novex®, Invitrogen Ltd, Paisley, UK) and dried using DryEase® Mini-Gel Drying System (Invitrogen Ltd, Paisley, UK) according to manufacturer’s instructions. Results Using the anti-FGF23 polyclonal antibody that recognizes the C-terminal of FGF23, two bands were detected in the standard material from the ELISA kit namely, at approximately ~32 kDa and at a lower molecular weight ~12 kDa suggestive of the full-length intact FGF23 and C-terminal fragment, respectively. This indicated the western blot method is capable of detecting both intact and C-terminal FGF23 fragments. The Gambian plasma samples were then used in the same method and only one band was detected, at ~32 kDa, namely the full-length intact FGF23 hormone. There was no evidence of the presence of non-intact FGF23 hormone in the plasma samples and there was no difference in proteins detected in the samples from children with rickets-like bone deformities (R1–R4) and from local community children (C1–C4; Fig. 2a).