Cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMP-NeuAc hydroxylase) participates in the hydroxylation reaction of CMP-NeuAc to form CMP-N- glycolylneuraminic acid (CMP-NeuGc). The hydroxylation is carried out by an enzyme complex composed of cytochrome b5, NADH cytochrome b5 reductase, and CMP-NeuAc hydroxylase in the presence of NADH. Other characteristic features of the hydroxylation are that (1) the reaction is a rate-limiting step for the expression of NeuGc; (2) CMP-NeuAc hydroxylase is a soluble and cytosolic protein, but the other enzymes, cytochrome b5 and NADH cytochrome b5 reductase, are endoplasmic reticulum (ER) membrane-bound proteins; and (3) the expression of NeuGc is tissue- and species-specific, and both phenotypes are regulated by CMP-NeuAc hydroxylase.


Sialic Acid Microsomal Fraction Acid Hydroxylation Acid Hydroxylase D86324 AF074480 


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© Springer Japan 2002

Authors and Affiliations

  • Akemi Suzuki
    • 1
  1. 1.RIKEN Frontier Research SystemSaitamaJapan

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