The present invention provides a method for selecting an intron for enhanced expression of a nucleotide sequence encoding a polypeptide, comprising: a) determining a mean free energy value per base pair of one or more introns b) determining a mean IMEter score of the one or more introns of (a) and c) selecting an intron having a mean free energy value per base pair of below about −0.268 kcal/mol/bp and a mean IMEter score of at least about −0.034/bp, thereby selecting an intron for enhanced expression of a nucleotide sequence encoding the polypeptide, wherein expression of a nucleotide sequence operably associated with the selected intron is enhanced as compared to expression of a nucleotide sequence not operably associated with an intron having a mean free energy value per base pair of below about −0.268 kcal/mol/bp and a mean IMEter score of at least about −0.034/bp.
