An important cofactor for carboxylation reaction is the vitamin Biotin. Four carboxylase groups (ACC, MCC, PCC and PC) are activated by binding to biotin and forming holocarboxylases, which in turn are responsible for several metabolic conversion in the Fatty Acid Synthesis, Leucine catabolism, propanoate metabolism and gluconeogenesis. Except for the ACC conversion from acetyl-CoA to malonyl-CoA starting the fatty acid synthesis, all other three interactions are connected to disorders. Furthermore, one can distinguish two "multiple carboxylase defects" (MCDs), which are connected to the conversion of biocytin into biotin (BTD), or unbound biotin to one of the apocarboxylases (HCSD). This pathway was inspired by Chapter 14 (edition 4) of the book of Blau (ISBN 3642403360 (978-3642403361)). b1a cc1 aka apo-[methylmalonyl-CoA:pyruvate carboxytransferase] aka propionyl-CoA aka pyruvate carboxylase aka trans-3-methylglutaconyl-CoA aka 3-methylbut-2-enoyl-CoA biotin covalantly bound to lysine ea9 aka Holocarboxylase Synthetase aka acetyl-CoA carboxylase aka acetyl-CoA carboxylase aka Propionate metabolism aka holo-[methylmalonyl-CoA:pyruvate carboxytransferase] aka apo-[propionyl-CoA:carbon-dioxide ligase (ADP-forming)] aka holo-[propionyl-CoA:carbon-dioxide ligase (ADP-forming)] aka apo-[3-methylcrotonoyl-CoA:carbon-dioxide ligase (ADP-forming)] aka holo-[3-methylcrotonoyl-CoA:carbon-dioxide ligase (ADP-forming)] aka pyruvate carboxylase aka pyruvate carboxylase ea9 ea9 3-Methylcrotonyl-CoA carboxylase 1 deficiency DOID:0080579 Disease 8930409 PubMed Biotinidase and its roles in biotin metabolism. Clin Chim Acta 1996 Hymes J Wolf B 9783642403361 ISBN Physician's Guide to the Diagnosis, Treatment, and Follow-Up of Inherited Metabolic Diseases Springer 2014 Nenad Blau Carlo Dionisi Vici K Michael Gibson Marinus Duran 3-Methylcrotonyl-CoA carboxylase 2 deficiency DOID:0080580 Disease 22116691 PubMed Biotin: biochemical, physiological and clinical aspects. Subcell Biochem 2012 Said HM 3-methylcrotonyl CoA carboxylase 1 deficiency pathway PW:0002576 Pathway Ontology biotinidase deficiency pathway PW:0002254 Pathway Ontology 3-Methylcrotonyl-CoA carboxylase deficiency DOID:0050710 Disease 3-methylcrotonyl CoA carboxylase 2 deficiency pathway PW:0002577 Pathway Ontology biotinidase deficiency DOID:856 Disease holocarboxylase synthetase deficiency DOID:859 Disease biotin metabolic pathway PW:0000139 Pathway Ontology holocarboxylase synthetase deficiency pathway PW:0002255 Pathway Ontology pyruvate carboxylase deficiency pathway PW:0001775 Pathway Ontology pyruvate carboxylase deficiency disease DOID:3651 Disease