The L232H mutant of the enhanced green fluorescent protein (EGFP) was expressed and crystallized. An X-ray diffraction data set was collected from the crystals to 1.53 Å resolution. An analysis of the three-dimensional structure revealed a stacking interaction between the amino-acid residues Н78 and Н232, which contributes to the fastening of the C-terminal region of the protein in the vicinity of the chromophore and influences chromophore maturation of hybrid fluorescent proteins produced by fusion of the target proteins with the C-terminus of EGFP. This hypothesis was experimentally confirmed by investigating chromophore maturation of the hybrid proteins fused to the N- and C-termini of EGFP and EGFP-L232H.