Atomic resolution structures of ribonuclease A at six pH values.Berisio, R., Sica, F., Lamzin, V.S., Wilson, K.S., Zagari, A., Mazzarella, L.
(2002) Acta Crystallogr.,Sect.D 58: 441-450
- PubMed: 11856829
- Primary Citation of Related Structures:  1KF2, 1KF4, 1KF5, 1KF7, 1KF8
- Also Cited By: 1YV4, 1YV6, 1YV7
- PubMed Abstract:
- Protein titration in the crystal state
Berisio, R.,Lamzin, V.S.,Sica, F.,Wilson, K.S.,Zagari, A.,Mazzarella, L.
(1999) J.Mol.Biol. 292: 845
The diffraction pattern of protein crystals extending to atomic resolution guarantees a very accurate picture of the molecular structure and enables the study of subtle phenomena related to protein functionality. Six structures of bovine pancreatic r ...
The diffraction pattern of protein crystals extending to atomic resolution guarantees a very accurate picture of the molecular structure and enables the study of subtle phenomena related to protein functionality. Six structures of bovine pancreatic ribonuclease at the pH* values 5.2, 5.9, 6.3, 7.1, 8.0 and 8.8 and at resolution limits in the range 1.05-1.15A have been refined. An overall description of the six structures and several aspects, mainly regarding pH-triggered conformational changes, are described here. Since subtle variations were expected, a thorough validation assessment of the six refined models was first carried out. Some stereochemical parameters, such as the N[bond]C(alpha)[bond]C angle and the pyramidalization at the carbonyl C atoms, indicate that the standard target values and their weights typically used in refinement may need revision. A detailed comparison of the six structures has provided experimental evidence on the role of Lys41 in catalysis. Furthermore, insights are given into the structural effects related to the pH-dependent binding of a sulfate anion, which mimics the phosphate group of RNA, in the active site. Finally, the results support a number of thermodynamic and kinetic experimental data concerning the role of the disulfide bridge between Cys65 and Cys72 in the folding of RNase A.
Centro di Studio di Biocristallografia, CNR, Via Mezzocannone 6, I-80134 Napoli, Italy.