Specificity of human trans-sialidase as probed with gangliosides.
It has been shown that human blood contains a soluble 67 kDa enzyme, belonging by its donor-acceptor properties to trans-sialidases. The enzyme is capable of both cleaving and synthesizing alpha2-3 and alpha2-6 sialosides [Atherosclerosis2001, 159, 103]. In this work the study of donor-acceptor specificity of the new enzyme was extended. It has been demonstrated in vitro that trans-sialidase possesses the ability of transferring Neu5Ac residue to acceptor (asialofetuin) both from alpha2-3- (GM1, GM3, GD1a), and alpha2-8-sialylated gangliosides (GD3 and GD1b, but not GT1b and GQ1b). Transfer of radiolabeled Neu5Ac from fetuin to glycosphingolipids demonstrated that Lac-Cer>mono- and disialogangliosides>GT1b>GQ1b were acceptors for this enzyme. Two methods were used to reveal whether alpha2-8 bond can be formed between Neu5Ac residues during trans-sialylation, that is immunochemical detection using monoclonal antibodies specific to alpha2-8 di- and oligosialic acids, and fluorometric C7/C9 analysis. Both methods demonstrated the formation of Neu5Acalpha2-8Neu5Ac termination by trans-sialidase, for example, in case of the use 3'SL as sialic acid donor and Neu5Ac-PAA or LDL as acceptor. Thus, human trans-sialidase in vitro displays wide substrate specificity: the enzyme is capable of digesting as well as synthesizing alpha2-3, alpha2-6, and alpha2-8 sialosides.
Nikonova
E Yu
EY
Shemyakin Institute of Bioorganic Chemistry, Russian Academy of Science, Moscow 117997, Russia.
Tertov
V V
VV
Sato
C
C
Kitajima
K
K
Bovin
N V
NV
D001212:Asialoglycoproteins / Q000737:chemistry; D003627:Data Interpretation, Statistical; D060748:Fetuins; D005470:Fluorometry; D005732:Gangliosides / Q000737:chemistry*; D006023:Glycoproteins; D006801:Humans; D015151:Immunoblotting; D066298:In Vitro Techniques; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000302:isolation & purification; D019158:N-Acetylneuraminic Acid / Q000737:chemistry; D009439:Neuraminidase / Q000737:chemistry* / Q000302:isolation & purification; D012794:Sialic Acids / Q000737:chemistry; D013379:Substrate Specificity; D000509:alpha-Fetoproteins / Q000737:chemistry
D001212:Asialoglycoproteins; D060748:Fetuins; D005732:Gangliosides; D006023:Glycoproteins; D008077:Lipoproteins, LDL; D012794:Sialic Acids; D000509:alpha-Fetoproteins; C017029:asialofetuin; C069715:trans-sialidase; D009439:Neuraminidase; D019158:N-Acetylneuraminic Acid