Biotin

Biotin is a vitamin and a coenzyme commonly associated with enzymes performing carboxylation reactions. Biotin is typically linked covalently to carboxylase enzymes through the -amino nitrogen of lysine. Biotin is very tightly bound by avidin, a protein found in egg white. The strong interaction between these molecules is exploited in numerous purification techniques in biotechnology.

See also: Acetyl CoA Carboxylase, Avidin