1KF3

Atomic resolution structures of ribonuclease A at six pH values.

(2002) Acta Crystallogr D Biol Crystallogr 58: 441-450

• PubMed: 11856829 Search on PubMed
• DOI: https://doi.org/10.1107/s0907444901021758
• Primary Citation of Related Structures:  
  1KF2, 1KF3, 1KF4, 1KF5, 1KF7, 1KF8


• PubMed Abstract: 
  

  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.

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Organizational Affiliation: 

Centro di Studio di Biocristallografia, CNR, Via Mezzocannone 6, I-80134 Napoli, Italy.