A polypeptide comprising a biological activity, said polypeptide consisting of a peptide of interest, a single chorionic gonadotropin carboxy terminal peptide attached to the amino terminus of said peptide, two chorionic gonadotropin carboxy terminal peptides attached to the carboxy terminus of said peptide, wherein said chorionic gonadotropin carboxy terminal peptide is from the beta- subunit of human chorionic gonadotropin and comprises the amino acid sequence SSSSKPPPSLP (SEQ ID NO: 43), and wherein said peptide of interest is a human growth hormone (hGh).