CMP-sialate synthase

This enzyme [EC 2.7.7.43], also referred to as CMP-A-acetylneuraminic acid synthetase and CMP-sialate synthase, catalyzes the conversion of CTP and A-acylneu-raminate to yield pyrophosphate and CMP-A-acylneu-raminate. The protein will act on both the A-acetyl and A-glycolyl derivatives. 

E. Schreiner, R. Christian, and E. Zribal, Synthesis of 9-deoxy-, 7,9-dideoxy-, and 4,7,9-trideoxy-iV-acetylneuraminic acid and their behaviour towards CMP-sialate synthase, Liebigs Ann. Chem. p. 93 (1990). 

The extensive manipulations which have been carried out on sialic acids themselves have been reviewed b) Tupp) and Gottschalk [63], Holmquist [101], Vliegenthart and Kammerling [102], in detail by Zbiral [4], and recently by von Itzstein and Kiefel [103]. This account will therefore give an overview of the transformations which have been carried out, resulting in modification at every carbon of NeuSAc. The derivatives prepared have been used to probe the requirements of sialic acid-recognising proteins, in particular the enzymes involved in sialic acid metabolism such as CMP-sialate synthase, sialidases, and NeuSAc aldolase. 

Free sialic acids are used by the enzymes of sialic acid metabolism, CMP-sialate synthase and Neu5Ac aldolase. However the majority of sialic acid-metabolising and -recognising proteins interact with glycosidically bound sialic acid. There-... 

Fig. 13. Metabolism scheme of sialic acids. Anabolic (solid arrow) and catabolic (dashed arrow) reactions are indicated. For literature see the text. Enzymes 1, CMP-sialate synthase (EC 2.7.7.43) 2, sialyltransferases (EC 2.4.99.1.) 3, CMP-Neu5Ac hydroxylase (EC 1.14.99.18) 4, acetyl-CoA sialate 4-0-acetyltransferase (EC 2.3.1.44) 5, acetyl-CoA sialate 7(9)-0-acetyltransferase (EC 2.3.1.45) 6,. S-adenosyl-L-methionine sialate 8-O-methyltransferase (proposed EC 2.1.1.78) 7, sialate 4- or 9-0-acetylesterases (EC 3.1.1.53) 8, sialidase (EC 3.2.1.18) 9, sialate-pyruvate lyase (aldolase EC 4.1.3.3). Both Neu5Ac and Neu5Gc can be O-acetylated by the two O-acetyltransferases. There may also exist a sulfotransferase, since sulfated sialic acids have been found in e.g. echinoderms [13,577]. ( ), Sialic-acid-accepting nascent glycoconjugate.

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