ISSN:
1399-0047
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
The non-covalent combination of residues 1–118 of RNase A with a synthetic 14-residue peptide containing residues 111–124 of the molecule forms a highly active semisynthetic enzyme, RNase 1–118:111–124. With this enzyme, the roles played by the six C-terminal residues in generating the catalytic efficiency and substrate specificity of RNase can be studied using chemically synthesized analogs. The structure of RNase 1–118:111–124 from 43% aqueous ethanol has been determined using molecular-replacement methods and refined to a crystallographic R-factor of 0.166 for all observed reflections in the range 7.0–1.6 Å (Protein Data Bank file ISSC). The structure is compared with the 2.0 Å structure of RNase A from 43% aqueous 2-methyl-2-propanol and with the 1.8 Å structure of the semisynthetic enzyme obtained from crystals grown in concentrated salt solution. The structure of RNase 1–118:111–124 from aqueous ethanol is virtually identical to that of RNase A from aqueous 2-methyl-2-propanol. Half of the crystallographically bound water molecules are not coincident, however. The structure is somewhat less similar to that of RNase 1–118:111–124 from salt solutions, with a major difference being the positioning of active-site residue His119.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0907444995004574
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