Mass spectrometry and X-ray diffraction analysis of two crystal types of Dioclea virgata lectin: an antinociceptive protein candidate to structure/function analysis.

The lectin from seeds of Dioclea virgata (DvirL) was purified in a single step affinity chromatography, sequenced by tandem mass spectrometry and submitted to crystallization and biological experiments. DvirL has a molecular mass of 25,412 ± 2 Da and the chains β and γ has 12,817 Da ± 2 and 12,612 Da ± 2, respectively. Primary sequence determination was assigned by tandem mass spectrometry and revealed a protein with 237 amino acids and 87% of identify with ConA. The protein crystals were obtained native and complexed with X-Man using vapor-diffusion method at a constant temperature of 293 K. A complete X-ray dataset was collected at 1.8 Å resolution. DvirL crystals were found to be orthorhombic, belonging to the space group I222, with a unit cell parameters a = 647.5 Å, b = 86.6 Å, c = 90.2 Å. Molecular replacement search found a solution with a correlation coefficient of 77.1% and an R(factor) of 44.6%. The present study also demonstrated that D. virgata lectin presents edematogenic and antinociceptive activities in rodents electing this protein as a candidate to structure/function analysis.