Human proinsulin, the single-chain peptide precursor of insulin, consists of the insulin A and B chains connected by the 31 amino acid C-peptide. Cleavage of proinsulin by proteolytic enzymes produces insulin and free C-peptide.

Zinquin ethyl ester is a cell membrane-penetrating and selective fluorescent probe for zinc ions that measures intracellular levels of Zn(2+) and Ca(2+) ions and can be used to stain early embryos.

Sodium acetate is Commonly used laboratory reagent.