alpha-Ketoisovaleric acid is an abnormal metabolite that arises from the incomplete breakdown of branched-chain amino acids. alpha-Ketoisovaleric acid is a neurotoxin an acidogen and a metabotoxin.

C-Peptide, dog is a component of proinsulin, released from pancreatic beta cells into blood together with insulin. The C-peptide of proinsulin is important for the biosynthesis of insulin but has for a long time been considered to be biologically inert.

Cyanine5 NHS ester chloride is a reactive dye with red fluorescence that requires a small amount of organic cosolvent (such as DMF or DMSO) to label amino groups in peptides, proteins, and oligonucleotides.