Vanadate complex spectroscopy at the RNase A active site

✍ Scribed by M. Krauss; B. D. Wladkowski

• Book ID: 101252035
• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 242 KB
• Volume: 69
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1998)69:1<11::aid-qua3>3.0.co;2-#

✦ Synopsis

Knowledge of the ionicity of the phosphorane intermediate is important to the analysis of the microscopic mechanism of the hydrolysis of the phosphate ester Ž . bond by ribonuclease A RNase A . Five-coordinate uridine vanadate, an analog of the phosphorane, binds to RNase A as the monoanion. The absorption spectra of the vanadate is a probe of the electronic structure of the active site. An in vacuo theoretical y Ž . model of H VO is calculated to have transitions only in the far ultraviolet UV .

4 5 However, H VO C H y has one in the near UV as well as others further into the UV. The 2 5 2 4

transition energy of the monoanion calculated in the field of the protein active site with effective fragment potentials shifts modestly to the red. Broad monoanion absorptions are predicted which would overlap an observed incomplete very broad absorption attributed to the complex of uridine vanadate with RNase A. The absorption bands of neutral ethylene glycol vanadate are predicted to be further to the red but also overlap the experimental absorption.