avidin A protein in raw egg‐white which binds biotin, preventing its absorption. People who consume abnormally large amounts of uncooked egg (several dozen eggs per week) have been reported to show biotin deficiency. Avidin is denatured on cooking, and does not combine with biotin; indeed cooked egg is a rich source of available biotin.

avidin A glycoprotein component of egg white that binds strongly to the vitamin biotin. Proteins and nucleic acids can be linked to biotin (biotinylated), and the avidin–biotin reaction can then be used in a number of assay methods, such as antigen–antibody reactions or DNA hybridization. For example, enzymes conjugated with avidin can be used to bind to biotinylated antibodies.