| 摘要 |
The present invention relates to an improved process for preparing a polypeptide or pharmaceutically acceptable salt thereof comprising L-tyrosine, L-alanine, L-glutamate, and L-lysine. The polypeptide or pharmaceutically acceptable salt thereof is preferably glatiramer acetate. The process comprises: (a) polymerizing a mixture of N-carboxyanhydride of L-tyrosine, N-carboxyanhydride of L-alanine, N-carboxyanhydride of a protected L-glutamate and N-carboxyanhydride of a protected L-lysine, in a polar aprotic solvent in the presence of an initiator, to form a protected polypeptide; (b) admixing an acid with the protected polypeptide formed in Step (a) and a solvent, to form a product; and (c) admixing a substance selected from the group consisting of an alkali or alkaline earth metal hydroxide, a carbonate, a hydrogencarbonate, and mixtures thereof, with the product formed in Step (b), and a solvent or a mixture of a solvent and water, to form a deprotected polypeptide or a pharmaceutically acceptable salt thereof.
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