SDS/PAGE of HpyHU-RN (lane 1), HpyHU (lanes 2–5) and HBsu (lanes 6–9). Lanes 1, 2 and 6 contain 1 μg of unmodified proteins, and lanes 3–5 and 7–9 contain 1, 2 and 3 μg respectively of HpyHU (lanes 3–5) or HBsu (lanes 7–9) cross-linked with glutaraldehyde in bicine (pH 8.5)/50 mM NaCl. With a theoretical pI of 9.05, HpyHU migrates slightly slower than predicted from the calculated molecular mass of 10422 Da. Molecular-mass markers are indicated at the left (in kDa).