Collagen types I, II, III, IV, and V are synthesized as precursor molecules called procollagens. A procollagen peptide contains an additional peptide sequence, the propeptide, at its amino- and carboxy-terminal ends. Propeptides facilitate the winding of procollagen molecules into a triple-helix conformation within the endoplasmic reticulum. These propeptides are then cleaved from the collagen triple helix molecule during its secretion, after which the collagens polymerize into extracellular collagen fibrils. Thus, the amount of free propeptides directly correlates with collagen molecule synthesis. Procollagen Type I C-peptide (PIP) has been extensively referenced in correlation studies between collagen levels and certain health disorders such as bone disease, alcoholic liver disease, liver cirrhosis, and scirrhous (Borrmann type IV) adenocarcinoma of the stomach.
ELISA Kits for PIP Detection
The Procollagen Type I C-Peptide (PIP) EIA Kit (Precoated) is a 96-well format in vitro enzyme immunoassay intended for the quantification of human, bovine, canine, and horse PIP in plasma, serum, cell culture extract, cell culture supernatant, and other biological fluids. The kit is a solid-phase procollagen sandwich ELISA that utilizes two mouse monoclonal PIP antibodies; the capture antibody is coated onto the plate, while the detection antibody is peroxidase-labeled. The procollagen ELISA takes advantage of a one-step format in which test samples and peroxidase-labeled anti-PIP are simultaneously added to the wells of the plate and incubated. During incubation, PIP becomes bound to the antibody coating the plate and is tagged by peroxidase-labeled anti-PIP at its opposite side. A substrate (H2O2, TMBZ) is added and the reaction between peroxidase and substrate results in color development. The amount of sample PIP is determined by measuring absorbance using an EIA plate reader. Accurate PIP sample concentrations can be determined by comparing their specific absorbance with that obtained for the supplied kit standard (via a standard curve).
Antibodies for PIP Detection
Monoclonal Anti-Human Procollagen Type I C-Peptide Antibodies (Clone PC5-5 and Clone PC8-7) are suitable for monitoring collagen synthesis via Western blot (WB) detection of non-denatured antigen in cell culture supernatant as well as in FFPE and frozen tissue sections.