The present invention relates to a polypeptide comprising at least one alpha-helix having synthetically attached thereto a plurality of therapeutic or diagnostic moieties, wherein said therapeutic or diagnostic moieties may be the same or different and are spatially oriented on the polypeptide so as to minimise interactions between said moieties. Further aspects of the invention relate to a pharmaceutical composition comprising the polypeptide; a polynucleotide sequence encoding the polypeptide; an expression vector comprising said polynucleotide sequence; and a host cell transformed with said expression vector. The invention also provides a method of treatment comprising administering to a subject in need thereof a therapeutically effective amount of said polypeptide.