Generation of a non-prolyl cis peptide bond in ribonuclease T1.
The cis conformation of the 38-39 peptide bond of ribonuclease T1 is retained after the replacement of cis Pro39 by an alanine residue. This conformation is demonstrated by the presence of a NOESY cross-peak in the NMR spectrum between the C alpha protons of Tyr38 and Ala39 in the Pro39-->Ala variant. The presence of this non-prolyl cis peptide bond explains the retention of the catalytic activity, the strong decrease in stability and the changes in the folding mechanism that were observed after the Pro39-->Ala mutation in ribonuclease T1. We suggest that a cis peptide bond is retained in a protein after the substitution of a cis proline at positions, where a trans bond would destabilize the protein more strongly than a non-prolyl peptide bond in the energetically unfavourable cis conformation.
Laboratorium für Biochemie, Universität Bayreuth, Germany.
L M
LM
Mayr
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D
Willbold
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P
Rösch
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Schmid
D000409:Alanine / Q000737:chemistry; D002384:Catalysis; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000737:chemistry; D011392:Proline / Q000737:chemistry; D011487:Protein Conformation; D006163:Ribonuclease T1 / Q000737:chemistry*
D010455:Peptides; D011392:Proline; D006163:Ribonuclease T1; D000409:Alanine