Human phosphoglucose isomerase: expression, purification, crystallization and preliminary crystallographic analysis

Phosphoglucose isomerase (PGI) is the second enzyme in the glycolytic pathway and catalyzes an aldose-ketose isomerization. Outside the cell, PGI has been found to function as both a cytokine and as a growth factor. The human pgi gene was cloned and the expressed enzyme was purified to homogeneity. Isomorphous crystals were obtained under two conditions and belong to the P2₁2₁2₁ space group, with unit-cell parameters a = 80.37, b = 107.54, c = 270.33 Å. A 94.7% complete data set was obtained and processed to a limiting resolution of 2.6 Å. The asymmetric unit contains two hPGI dimers according to density calculations, a self-rotation function map and molecular-replacement solution.