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In enzymology, a vitamin B₁₂-transporting ATPase (EC 3.6.3.33) is an enzyme that catalyzes the chemical reaction

ATP + H₂O + vitamin B_12out ${\displaystyle \rightleftharpoons }$ ADP + phosphate + vitamin B_12in

The 3 substrates of this enzyme are ATP, H₂O, and vitamin B₁₂, whereas its 3 products are ADP, phosphate, and vitamin B₁₂.

This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides to catalyse transmembrane movement of substances. The systematic name of this enzyme class is ATP phosphohydrolase (vitamin B₁₂-importing). This enzyme participates in abc transporters - general.

Structural studies

As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 1L7V and 2QI9.

References

• Kuan G, Dassa E, Saurin W, Hofnung M, Saier MH (1995). "Phylogenetic analyses of the ATP-binding constituents of bacterial extracytoplasmic receptor-dependent ABC-type nutrient uptake permeases". Res. Microbiol. 146 (4): 271–8. doi:10.1016/0923-2508(96)81050-3. PMID 7569321.
• Saier MH Jr (1998). "Molecular phylogeny as a basis for the classification of transport proteins from bacteria, archaea and eukarya". Adv. Microb. Physiol. Advances in Microbial Physiology. 40: 81–136. doi:10.1016/S0065-2911(08)60130-7. ISBN 978-0-12-027740-7. PMID 9889977.
• Friedrich MJ, de Veaux LC, Kadner RJ (1986). "Nucleotide sequence of the btuCED genes involved in vitamin B12 transport in Escherichia coli and homology with components of periplasmic-binding-protein-dependent transport systems". J. Bacteriol. 167 (3): 928–34. doi:10.1128/JB.167.3.928-934.1986. PMC 215960. PMID 3528129.

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