An undecagold cluster was covalently attached to whole ribosomes and to their small and large subunits prior to their crystallization. X-ray crystallographic data were collected from crystals of the first two. The same cluster was bound to tRNA(phe) from E. coli at base 47. It was found that the modified tRNA molecule binds to the ribosome and can be aminoacylated by its cognate synthetase. The gold cluster modified tRNA(phe) may be used for phasing diffraction data of crystals of complexes containing it, mimicking defined states in the process of protein biosynthesis.