Expression, purification and preliminary crystallographic studies of α-amylase isozyme 1 from barley seeds

The germinating barley seed contains two major α-amylase isozyme families, AMY1 and AMY2, involved in starch degradation to provide energy used by the plant embryo for growth. Many years of difficulty in growing three-dimensional crystals of natural AMY1 have now been overcome by a nonapeptide truncation of the enzyme C-terminus. The truncated enzyme was overexpressed in Pichia pastoris, purified and crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol 8000 as precipitant and 2-propanol as an additive. Crystals belong to the orthorhombic space group P2₁2₁2, with unit-cell parameters a = 88.36, b = 72.82, c = 61.74 Å and one molecule per asymmetric unit.