Question

Biotin is the molecule to which is bound in the process of being transferred to . The carboxyl group of biotin forms an amide bond with a specific side chain of . The reaction produces , which then undergoes further reactions in gluconeogenesis.

Answer 1

In humans, biotin is involved in important metabolic pathways such as gluconeogenesis, fatty acid synthesis, and amino acid catabolism. Biotin regulates the catabolic enzyme propionyl-CoA carboxylase at the posttranscriptional level whereas the holo-carboxylase synthetase is regulated at the transcriptional level.

Biotin functions as a cofactor that aids in the transfer of CO2 groups to various target macromolecules. Biotin has nine host enzymes with which it is associated. Humans only have four of these enzymes:

Pyruvate carboxylase (formation of oxaloacetate from pyruvate)

beta-Methylcrotonyl-CoA carboxylase

Propionyl-CoA carboxylase (conversion of propionyl-CoA to succinyl-CoA)

Acetyl-CoA carboxylase (carboxylation of acetyl-CoA to malonyl-CoA)

Biotin's other target enzymes include Steptividin, Avidin, homocitrate synthetase, and isopropylmalate synthase.

In order to provide glucose for vital functions such as the metabolism of RBC's and the CNS during periods of fasting (greater than about 8 hrs after food absorption in humans), the body needs a way to synthesis glucose from precursors such as pyruvate and amino acids. This process is referred to as gluconeogenesis.