Spectral properties of phosphopyridoxyl-Lys-7(-41)-ribonuclease A
| Autor: | M.Ya. Karpeisky, L.V. Karabachyan, T.G. Geidarov, S.N. Borisova, S.V. Shlyapnikov, S.M. Dudkin |
|---|---|
| Rok vydání: | 1975 |
| Předmět: |
Circular dichroism
Protein Denaturation Binding Sites Absorption spectroscopy biology Chemistry Stereochemistry Protein Conformation Circular Dichroism Lysine Temperature Active site Chromophore Hydrogen-Ion Concentration Biochemistry Genetics and Molecular Biology (miscellaneous) Residue (chemistry) Ribonucleases Absorption band Pyridoxal Phosphate biology.protein Molecule Spectrophotometry Ultraviolet Ribonuclease Protein Binding |
| Zdroj: | Biochimica et biophysica acta. 386(1) |
| ISSN: | 0006-3002 |
| Popis: | We have studied the spectral properties of RNAase A containing a phosphopyridoxyl residue at the e-NH2 group of Lys7 or Lys14. The overall conformations of the native and modified enzymes were shown to be rather similar. All three proteins have similar circular dichroism spectra within the 220–300-nm region, and similar thermal transition temperatures. All the changes in the RNAase A molecule modified are located in close proximity to the alkylated lysine residue. The phosphopyridoxyl group of ( P- Pxy ) e - Lys 41 - RNAase A is situated directly at the enzyme active site and is 25% buried in the protein globule. The P-pyridoxyl group of (P- Pxy ) e - Lys 7 - RNAase A was shown to be located in the vicinity of the active site and to be more exposed to the solvent. In the pyridoxyl phosphate absorption band, optical activity is induced in both proteins. Study of the pH dependence of the changes occurring in the circular dichroism and absorption spectra has shown that in the modified proteins, the pyridoxyl phosphate chromophore is rather sensitive to the ionic state of the surrounding medium and serves as a “reporter” group when the relationship between structure and function of the RNAase A active site is being investigated. |
| Databáze: | OpenAIRE |
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