Download MendeleyStrain Relief at the Active Site of Phosphoserine Aminotransferase Induced by Radiation Damage.
Dubnovitsky, A.P., Ravelli, R.B.G., Popov, A.N., Papageorgiou, A.C.(2005) Protein Sci 14: 1498
- PubMed: 15883191
- DOI: https://doi.org/10.1110/ps.051397905
- Primary Citation of Related Structures:
2BHX, 2BI1, 2BI2, 2BI3, 2BI5, 2BI9, 2BIA, 2BIE, 2BIG - PubMed Abstract:
The X-ray susceptibility of the lysine-pyridoxal-5'-phosphate Schiff base in Bacillus alcalophilus phosphoserine aminotransferase has been investigated using crystallographic data collected at 100 K to 1.3 A resolution, complemented by on-line spectroscopic studies. X-rays induce deprotonation of the internal aldimine, changes in the Schiff base conformation, displacement of the cofactor molecule, and disruption of the Schiff base linkage between pyridoxal-5'-phosphate and the Lys residue. Analysis of the "undamaged" structure reveals a significant chemical strain on the internal aldimine bond that leads to a pronounced geometrical distortion of the cofactor. However, upon crystal exposure to the X-rays, the strain and distortion are relaxed and eventually diminished when the total absorbed dose has exceeded 4.7 x 10(6) Ggamma. Our data provide new insights into the enzymatic activation of pyridoxal-5'-phosphate and suggest that special care should be taken while using macromolecular crystallography to study details in strained active sites.
Organizational Affiliation:
Turku Centre for Biotechnology, University of Turku, Finland.
