Human Plasma trans-Sialidase Donor and Acceptor Specificity

V. V. Tertov¹, E. Yu. Nikonova^2*, N. E. Nifant'ev³, N. V. Bovin², and A. N. Orekhov⁴

¹Institute of Experimental Cardiology, Cardiology Research Center, Russian Academy of Medical Sciences, 3-ya Cherepkovskaya ul. 15a, Moscow, 121552 Russia; fax: (095) 414-6731; E-mail: inat@cardio.ru

²Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow, 117871 Russia; fax: (095) 330-5592; E-mail: bovin@carb.siobc.ras.ru or boycova@yandex.ru

³Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky pr. 47, Moscow, Russia; fax: (095) 135-8784

⁴Department of Biophysics, School of Biology, Lomonosov Moscow State University, Moscow, 119899 Russia

^* To whom correspondence should be addressed.

Received May 17, 2001; Revision received June 13, 2001

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Earlier we have isolated from human plasma desialylated low density lipoproteins (dLDL) and showed that, first, dLDL induce cholesterol esters accumulation--the main process accompanying atherosclerosis development. Second, the process of lipoprotein desialylation took place in plasma, and, finally, sialic acids removed from LDL are transferred to other serum glycoconjugates. In this study we have isolated from human plasma an enzyme transferring sialic acid residues (trans-sialidase) by affinity chromatography and studied its donor and acceptor specificity. Isolated enzyme in the presence of saccharide-acceptor can remove sialic acids from different lipoproteins, glycoproteins (fetuin, transferrin), and gangliosides (GM3, GD3, GM1, GD1a, GD1b). Plasma enzyme translocates alpha2-6, alpha2-3 and to a lower extent alpha2-8 bonded sialic acids. Sialoglycoconjugates of human serum erythrocytes, serum lipoproteins, glycoproteins, and gangliosides can serve as donors of sialic acid for trans-sialidase. Desialylated lipoproteins, especially dLDL, are more preferable sialic acid acceptors. Transferred sialic acid is found to be alpha2-6, alpha2-3, and alpha2-8 connected.

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KEY WORDS: atherosclerosis, human plasma, trans-sialidase, lipoproteins, gangliosides, glycoconjugates, sialic acid

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