N-acetyl to N-glycolylneuraminic acid 'convertase'

Wed Jun 21 18:22:06 EST 1995

On 21 Jun 1995, Iain Wilson wrote:

> Posted on behalf of Prof. Niegl Jenkins:
> *********************************************************
> Does anyone know details about the enzyme responsible for conversion of 
> N-acetyl to N-glycolylneuraminic acid? Has it been cloned, if so has anyone 
> got the cDNA?
> *********************************************************
> Prof. Nigel Jenkins 
> njenkins at dmu.ac.uk
> School of Applied Sciences
> De Montfort University
> Leicester LE1 9BH, U.K.
> Tel:++116 257 7118
> Fax:++116 257 7287
> ---------------------------------------------------------------
> Iain Wilson                        Institut fuer Chemie           
> Tel: 43-1-47654-6065               Universitaet fuer Bodenkultur   
> Fax: 43-1-310-5176                 Gregor-Mendel-Strasse 33
> E-mail: wilson at edv1.boku.ac.at     A-1180, WIEN, Austria
To Prof. Jenkins and others who are interested:

	I'm not really an expert in this particular area, but I am 
familiar with one or two key papers, which should be quite informative.  
The conversion of NeuAc to NeuGc actually occurs at the level of the 
nucleotide sugar:   CMP-NeuAc is converted to CMP-NeuGc.

	The key work has been done by Akemi Suzuki and co-workers.  They
published data (Y. Kozutsumi et al., J. Biochem 108, 704-6, 1990) supporting
the hypothesis that the conversion was done by a three enzyme complex,
cytochrome b5, NADH dependent cytochrome b5 reductase, and CMP-NeuAc
hydroxylase, of which the last seems to be the rate limiting step.

	Last year the same group published the purification of the NeuAc 
hydroxylase from mouse liver (T. Kawano et al., J. Biol. Chem. 269, 9024-9, 
1994).  The enzyme is a 64 kDa polypeptide.  They state in this paper 
(published in March '94) that cDNA cloning is in progress.

	I hope this helps.

				Jim Mahoney
				Dept. of Pharmacology
				Johns Hopkins School of Medicine

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