A covalent conjugate between a polypeptide glycosylated or unglycosylated secuón and a group of polymer modification, corresponding said polypeptide secuón a precursor polypeptide and comprises a sequence of linked glycosylation exogenously O, said group of polymeric modifying conjugated to said polypeptide being the secuón in said sequence linked glycosylation O through a linking group to glycosyl, wherein said binding group glycosyl is interposed between and covalently linked to both said polypeptide secuón as to the group of polymer modification, with the proviso that said precursor polypeptide is not a member selected from human growth hormone (hGH), stimulating factor granulocyte colony (G-CSF), interferon-alpha (INF-alpha), peptide-1 glucagon (GLP-1) and growth factor 10 fibroblast (FGF), wherein said sequence with glycosylation ion exogenous or is a member selected from: (X) MPTP (X) mPTEI (P) n, (X) mPTQA (P) n, (X) MPTINT (P) n, (X) mPTTVS (P) n , (X) mPTTVL (P) n, (X) mPTQGAM (P) n, (X) mTET (P) n, (X) mPTVL (P) n, (X) mPTLS (P) n, (X) mPTDA (P) n, (X) mPTEN (P) n, (X) mPTQD (P) n, (X) Mptas (P) n, (X) mPTQGA (P) n, (X) mPTSAV (P) n, (X) mPTTLYV (P) n, (X) mPSSG (P) n (X) mPSDG (P) n, m and n are integers independently selected from 0 and 1 P is proline and X is a member independently selected from glutamic acid (E), glutamine (Q), aspartic acid (D), asparagine (N), threonine (T), serine (S) and uncharged amino acids.Un conjugado covalente entre un polipéptido del secuón glicosilado o no glicosilado y un grupo de modificación polimérico, correspondiendo dicho polipéptido del secuón a un polipéptido precursor y comprendiendo una secuencia de glicosilación con unión en O exógena, estando dicho grupo de modificación polimérico conjugado a dicho polipéptido del secuón en dicha secuencia de glicosilación con unión en O a través de un grupo de unión a glicosilo, en el que dicho grupo de unión a glicosilo está interpuesto entre y unido covalentemente tanto a dich
