Biocytin is biotin bound to lysine as seen in its structure below.
Free biotin is believed to be highly absorbed. Before uptake, biocytin is acted on by the enzyme biotinidase, forming free biotin and lysine. Free biotin is then taken up into the enterocyte through the sodium-dependent multivitamin transporter (SMVT), as shown below1,4,5.
Most biotin is excreted in the urine.
References & Links
1. Gropper SS, Smith JL, Groff JL. (2008) Advanced nutrition and human metabolism. Belmont, CA: Wadsworth Publishing.
4. Said H, Mohammed Z. (2006) Intestinal absorption of water-soluble vitamins: An update. Curr Opin Gastroenterol 22(2): 140-146.
5. Zempleni J, Wijeratne SSK, Hassan Y. (2009) Biotin. Biofactors 35(1): 36-46.