C-peptide is a 31-amino acid protein processed from proinsulin, which is produced in pancreatic beta cells. C-peptide is derived from the center of proinsulin, between the insulin B chain at the N-terminus and the insulin A chain at the C-terminus. One molecule of C-peptide corresponds to one insulin molecule produced from proinsulin processing.
The physiological function of C-peptide is unclear. It has a half-life 2–5 times longer than that of insulin, is thought to be at a higher concentration than insulin in the peripheral blood of healthy individuals, and its concentration in the blood may reflect the production of proinsulin in the pancreas more accurately than insulin concentration. Unlike insulin, C-peptide is excreted in the urine at levels 20–50 times higher than in blood. The average insulin production ability of pancreatic beta cells can be monitored by measuring excretion of C-peptide in 24-hour urine collection.
This kit is a single antibody-antigen competitive EIA method designed to quantitatively measure C-peptide in serum, plasma, urine, and cell culture media, using a rabbit polyclonal antibody that reacts with C-peptide from human, mouse and rat samples.