ðə daɪhˈiːdɹəl ˈæŋɡəl sˈɜːtʃ spˈeɪs ʌvðə sˈaɪd tʃˈeɪnz ɪz ɹᵻstɹˈɪktᵻd tʊ ɐ dɪskɹˈiːt sˈɛt ʌv ɹˈoʊɾeɪmɚz fɔːɹ ˈiːtʃ ɐmˈiːnoʊ ˈæsɪd pəzˈɪʃən ɪnðə pɹˈoʊtiːn wˈɪtʃ ɪz, ˈɑːbviəsli, ʌv fˈɪkst lˈɛŋθ.
The dihedral angle search space of the side chains is restricted to a discrete set of rotamers for each amino acid position in the protein (which is, obviously, of fixed length).