ExplorEnz: EC 2.4.1.212

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2.4.1.212

Accepted name:

hyaluronan synthase

Reaction:

(1) UDP-N-acetyl-α-D-glucosamine + β-D-glucuronosyl-(1→3)-N-acetyl-β-D-glucosaminyl-(1→4)-[nascent hyaluronan] = UDP + N-acetyl-β-D-glucosaminyl-(1→4)-β-D-glucuronosyl-(1→3)-N-acetyl-β-D-glucosaminyl-(1→4)-[nascent hyaluronan]
(2) UDP-α-D-glucuronate + N-acetyl-β-D-glucosaminyl-(1→4)-β-D-glucuronosyl-(1→3)-[nascent hyaluronan] = UDP + β-D-glucuronosyl-(1→3)-N-acetyl-β-D-glucosaminyl-(1→4)-β-D-glucuronosyl-(1→3)-[nascent hyaluronan]

For diagram of reaction, click here

Glossary:

GlcA = glucuronic acid

Other name(s):

spHAS; seHAS; Alternating UDP-α-N-acetyl-D-glucosamine:β-D-glucuronosyl-(1→3)-[nascent hyaluronan] 4-N-acetyl-β-D-glucosaminyltransferase and UDP-α-D-glucuronate:N-acetyl-β-D-glucosaminyl-(1→4)-[nascent hyaluronan] 3-β-D-glucuronosyltransferase

Systematic name:

Alternating UDP-N-acetyl-α-D-glucosamine:β-D-glucuronosyl-(1→3)-[nascent hyaluronan] 4-N-acetyl-β-D-glucosaminyltransferase and UDP-α-D-glucuronate:N-acetyl-β-D-glucosaminyl-(1→4)-[nascent hyaluronan] 3-β-D-glucuronosyltransferase (configuration-inverting)

Comments:

The enzyme from Streptococcus Group A and Group C requires Mg²⁺. The enzyme adds GlcNAc to nascent hyaluronan when the non-reducing end is GlcA, but it adds GlcA when the non-reducing end is GlcNAc [3]. The enzyme is highly specific for UDP-GlcNAc and UDP-GlcA; no copolymerization is observed if either is replaced by UDP-Glc, UDP-Gal, UDP-GalNAc or UDP-GalA. Similar enzymes have been found in a variety of organisms.

Links to other databases:

BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 39346-43-5

References:

1.	DeAngelis, P.L., Papaconstantinou, J. and Weigel, P.H. Molecular cloning, identification and sequence of the hyaluronan synthase gene from Group A Streptococcus pyogenes. J. Biol. Chem. 268 (1993) 19181–19184. [PMID: 8366070]
2.	Jing, W. and DeAngelis, P.L. Dissection of the two transferase activities of the Pasteurella multocida hyaluronan synthase: two active sites exist in one polypeptide. Glycobiology 10 (2000) 883–889. [DOI] [PMID: 10988250]
3.	DeAngelis, P.L. Molecular directionality of polysaccharide polymerization by the Pasteurella multocida hyaluronan synthase. J. Biol. Chem. 274 (1999) 26557–26562. [DOI] [PMID: 10473619]
4.	Tlapak-Simmons, V.L., Baron, C.A. and Weigel, P.H. Characterization of the purified hyaluronan synthase from Streptococcus equisimilis. Biochemistry 43 (2004) 9234–9242. [DOI] [PMID: 15248781]

[EC 2.4.1.212 created 2001, modified 2007]