Journal of Applied Sciences1812-56541812-5662Asian Network for Scientific Information10.3923/jas.2007.2154.2159Wei NeyYap RahmanBadarulhisam Abdul AzizAzila Abdul 122007715Baculovirus Expression Vector System (BEVS) is widely used for the production of recombinant glycoproteins, but it is not ideal for pharmaceutical glycoprotein production due to incomplete glycosylation. The factors that ensure successful glycosylation are the presence of sufficient amount of glycosyltransferases, sugar nucleotides as the substrate donor and the recombinant protein as the substrate acceptor. In this study, we analyzed the galactosylation process by the introduction of β-1,4galactosyltransferase (β-1,4GalT) as the glycosyltransferase of interest and uridine-5`-diphosphogalactose (UDP-Gal) as the substrate donor. Recombinant human transferrin (rhTf) as a model protein was used as the substrate acceptor. Insect cell lines have been reported to produce a small amount of β-1,4GalT and thus insufficient for effective galactosylation. In this study, we developed a method to produce galactosylated rhTf and optimized the expression of rhTf with better N-glycan quality. Recombinant β-1,4GalT was introduced during protein expression by the coinfection of the BEVS with baculovirus carrying bovine β-1,4GalT. To evaluate the extent of galactosylation by the coinfection strategy, a binding assay was established. In this binding assay, glycoprotein acceptor was absorbed onto ELISA plate surface. A lectin known as Ricinus communis agglutinin-I (RCA-I) labeled with peroxidase, was added and allowed to recognize Gal β1>4GlcNAc group on the N-glycan of the glycoprotein, followed by appropriate color reaction measurements. Coexpression between rhTf and β-1,4GalT did not show encouraging results due to the reduction of UDP-Gal upon baculovirus infection. This interesting finding suggested that the introduction of β-1,4GalT alone was not sufficient for successful galactosylation. Alternatively, post harvest glycosylation method strategy seems to be a promising technique in the improvement of glycoprotein quality.]]>Ailor, E., N. Takahashi, Y. Tsukamoto, K. Masuda, B.A. Rahman, D.L. Jarvis, Y.C. Lee and M.J. Betenbaugh,2000Trichoplusia ni insect cells: Effects of mammalian galactosyltransferase.]]>10837847Butters, T.D. and R.C. Hughes,1981640655671Chen, W. and O.P. Bahl,199126681928197David, R. O'Reilly, Lois K. Miller and A.L. Verne,1994Davidson, D.J., M.J. Fraser and F.J. Castillino,1990Spodoptera frugiperda) cells.]]>2955845590Hard, K., J.M. van Dorn, J.E. Thomas-Oates, J.P. Kamerling and D.J. van der Horst,199332766775Hsieh, P. and P.W. Robbins,1984Aedes albopitus mosquito cells.]]>25929752982Kubelka, V., F. Altmann, G. Kornfeld and L. Marz,1994308148157Kulakosky, P.C., P.R. Hughes and H.A. Wood,19988741745Kuroda, K., R. Geyer, W. Doergler and H.D. Klenk,1990174418428Nielson, L.K., G.K. Smyth and P.F. Greenfield,19927560563Ogonash, O.W., R.B. Freedman, N. Jenkins and B.C. Rooney,199614197202Reed, L.J. and H. Muench,193827493497Summers, M.D. and G.E. Smith,19871987Van Die, L., A. van Tetering, H. Bakker, D.H. van den Eijnden and D.H. Joziasse,19966157164