Sandbox Reserved 197: Difference between revisions

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==='''Proline Conformation'''===

The presence of ''cis'' [http://en.wikipedia.org/wiki/Cis_configuration]proline residues plays a large role in protein folding. In nature, most amino acids reside in a ''trans'' conformation, but due to their cyclic structure, prolines are more stable in the ''cis'' conformation than any other amino ~~acids~~. RNase A contains four proline residues, two reside in the ''cis'' conformation and two in the ''trans'' conformation. The importance of these conformations were demonstrated, based on the structure of RNase A variants, with several mutations to the wild type amino acid ~~sequences~~.

The presence of ''cis'' [http://en.wikipedia.org/wiki/Cis_configuration]proline residues plays a large role in protein folding. In nature, most amino acids reside in a ''trans'' conformation, but due to their cyclic structure, prolines are more stable in the ''cis'' conformation than any other amino acid. RNase A contains four proline residues, two reside in the ''cis'' conformation and two in the ''trans'' conformation. The importance of these conformations were demonstrated based on the structure of RNase A variants with several mutations to the wild type amino acid sequence.

Located in an outer <scene name='Sandbox_Reserved_197/Tyr92-pro93_loop/2'>loop</scene> of RNase A, the <scene name='Sandbox_Reserved_197/Tyr92-pro93/6'>Tyr92-Pro93</scene> peptide group of RNase A in its native state is found in the ''cis'' conformation. When proline was mutated to alanine, <scene name='Sandbox_Reserved_197/P93a/8'>P93A</scene>, a ''cis'' conformation still forms at position 93 which is an energetically unfavorable conformation for an alanine residue. Upon unfolding, Tyr92-Ala93 undergoes isomerization to form its more favorable ''trans'' conformation demonstrating that the ''cis'' conformation is favored by other interactions within the folded protein structure. Although the overall structure of RNase A is not affected by this mutation, the rate of folding greatly decreases upon insertion of the P93A mutation, suggesting an important kinetic contribution of ''cis'' prolines to protein folding.

Sandbox Reserved 197: Difference between revisions

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@@ Line 13: / Line 13: @@
 ==='''Proline Conformation'''===
-The presence of ''cis'' [http://en.wikipedia.org/wiki/Cis_configuration]proline residues plays a large role in protein folding.  In nature, most amino acids reside in a ''trans'' conformation, but due to their cyclic structure, prolines are more stable in the ''cis'' conformation than any other amino acids. RNase A contains four proline residues, two reside in the ''cis'' conformation and two in the ''trans'' conformation.  The importance of these conformations were demonstrated, based on the structure of RNase A variants, with several mutations to the wild type amino acid sequences.
+The presence of ''cis'' [http://en.wikipedia.org/wiki/Cis_configuration]proline residues plays a large role in protein folding.  In nature, most amino acids reside in a ''trans'' conformation, but due to their cyclic structure, prolines are more stable in the ''cis'' conformation than any other amino acid. RNase A contains four proline residues, two reside in the ''cis'' conformation and two in the ''trans'' conformation.  The importance of these conformations were demonstrated based on the structure of RNase A variants with several mutations to the wild type amino acid sequence.
 Located in an outer <scene name='Sandbox_Reserved_197/Tyr92-pro93_loop/2'>loop</scene> of RNase A, the <scene name='Sandbox_Reserved_197/Tyr92-pro93/6'>Tyr92-Pro93</scene> peptide group of RNase A in its native state is found in the ''cis'' conformation. When proline was mutated to alanine, <scene name='Sandbox_Reserved_197/P93a/8'>P93A</scene>, a ''cis'' conformation still forms at position 93 which is an energetically unfavorable conformation for an alanine residue.   Upon unfolding, Tyr92-Ala93 undergoes isomerization to form its more favorable ''trans'' conformation demonstrating that the ''cis'' conformation is favored by other interactions within the folded protein structure. Although the overall structure of RNase A is not affected by this mutation, the rate of folding greatly decreases upon insertion of the P93A mutation, suggesting an important kinetic contribution of ''cis'' prolines to protein folding.