Single crystals of bacteriophage T7 RNA polymerase

Single crystals of T7 RNA polymerase have been grown to a maximum size of 1.8 × 0.3 × 0.3 mm. The crystals are composed of fully intact T7 RNA polymerase which in enzymatically active upon dissolution. These crystals belong to the monoclinic space group P2₁ and have unit cell parameters a =114.5 Å, b=139.6 Å, c=125.7 Å, β=98.1° Self‐rotation function studies indicate that there are three molecules per asymmetricunit. The crystals diffract to at least 3.0 Å resolution. These are the first crystals of a DNA‐dependent RNA polymerase suitable for high‐resolution X‐ray structure determination.