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 a ''cis'' conformation. RNase A contains four proline residues, two reside in the ''cis'' conformation and two in the ''trans'' conformation. Importance of these conformations are demonstrated with several mutations to the wilde type.

The <scene name='Sandbox_Reserved_197/Tyr92-pro93/5'>Tyr92-Pro93</scene> peptide group of RNase A in its native state is found in the ''cis'' conformation. Despite a mutation from proline to alanine, <scene name='Sandbox_Reserved_197/P93a/7'>P93A</scene>, a ''cis'' conformation still forms~~; this~~ is ~~an 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 ~~protein~~ interactions ~~other than~~ the ~~proline residue~~. 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.

The <scene name='Sandbox_Reserved_197/Tyr92-pro93/5'>Tyr92-Pro93</scene> peptide group of RNase A in its native state is found in the ''cis'' conformation. Despite a mutation from proline to alanine, <scene name='Sandbox_Reserved_197/P93a/7'>P93A</scene>, a ''cis'' conformation still forms which is very unlikely 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 protein. 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.

<scene name='Sandbox_Reserved_197/Cis-proline114/1'>Asn113-Pro114</scene> resides in a ''cis'' conformation in its folded structure, but exists in the ''trans'' conformation in its unfolded state; therefore, steric restraints imposed by the rest of the protein must be responsible for this ''cis'' conformation. Insertion of <scene name='Sandbox_Reserved_197/P114g/1'>P114G</scene> causes the chain to adopt a ''trans'' conformation and causes a 9.3A movement of the loop where it is located. The kinetic rate and overall native conformation are not significantly effected by this mutation; however, locally, a rearrangement of the hydrogen-bonding network occurs. Results of this mutation confirm that steric hinderance of the protein causes formation of the ''cis'' conformation by a proline and is further energetically stabilized by hydrogen bonding, Van der Waals, and electrostatic interactions within the protein.

<scene name='Sandbox_Reserved_197/Cis-proline114/1'>Asn113-Pro114</scene> resides in a ''cis'' conformation in its folded structure, but exists in the ''trans'' conformation in its unfolded state; therefore, steric restraints imposed by the rest of the protein must be responsible for this ''cis'' conformation. Insertion of <scene name='Sandbox_Reserved_197/P114g/1'>P114G</scene> causes the chain to adopt a ''trans'' conformation and causes a 9.3Å movement of the loop where it is located. The kinetic rate and overall native conformation are not significantly effected by this mutation; however, locally, a rearrangement of the hydrogen-bonding network occurs. Results of this mutation confirm that steric hinderance of the protein causes formation of the ''cis'' conformation by a proline and is further energetically stabilized by hydrogen bonding, Van der Waals, and electrostatic interactions within the protein.

Sandbox Reserved 197: Difference between revisions

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@@ Line 14: / Line 14: @@
 ==='''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 a ''cis'' conformation. RNase A contains four proline residues, two reside in the ''cis'' conformation and two in the ''trans'' conformation. Importance of these conformations are demonstrated with several mutations to the wilde type.
-The <scene name='Sandbox_Reserved_197/Tyr92-pro93/5'>Tyr92-Pro93</scene> peptide group of RNase A in its native state is found in the ''cis'' conformation. Despite a mutation from proline to alanine, <scene name='Sandbox_Reserved_197/P93a/7'>P93A</scene>, a ''cis'' conformation still forms; this is an 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 protein interactions other than the proline residue. 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.
+The <scene name='Sandbox_Reserved_197/Tyr92-pro93/5'>Tyr92-Pro93</scene> peptide group of RNase A in its native state is found in the ''cis'' conformation. Despite a mutation from proline to alanine, <scene name='Sandbox_Reserved_197/P93a/7'>P93A</scene>, a ''cis'' conformation still forms which is very unlikely 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 protein. 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.
-<scene name='Sandbox_Reserved_197/Cis-proline114/1'>Asn113-Pro114</scene> resides in a ''cis'' conformation in its folded structure, but exists in the ''trans'' conformation in its unfolded state; therefore, steric restraints imposed by the rest of the protein must be responsible for this ''cis'' conformation. Insertion of <scene name='Sandbox_Reserved_197/P114g/1'>P114G</scene> causes the chain to adopt a ''trans'' conformation and causes a 9.3A movement of the loop where it is located. The kinetic rate and overall native conformation are not significantly effected by this mutation; however, locally, a rearrangement of the hydrogen-bonding network occurs. Results of this mutation confirm that steric hinderance of the protein causes formation of the ''cis'' conformation by a proline and is further energetically stabilized by hydrogen bonding, Van der Waals, and electrostatic interactions within the protein.
+<scene name='Sandbox_Reserved_197/Cis-proline114/1'>Asn113-Pro114</scene> resides in a ''cis'' conformation in its folded structure, but exists in the ''trans'' conformation in its unfolded state; therefore, steric restraints imposed by the rest of the protein must be responsible for this ''cis'' conformation. Insertion of <scene name='Sandbox_Reserved_197/P114g/1'>P114G</scene> causes the chain to adopt a ''trans'' conformation and causes a 9.3Å movement of the loop where it is located. The kinetic rate and overall native conformation are not significantly effected by this mutation; however, locally, a rearrangement of the hydrogen-bonding network occurs. Results of this mutation confirm that steric hinderance of the protein causes formation of the ''cis'' conformation by a proline and is further energetically stabilized by hydrogen bonding, Van der Waals, and electrostatic interactions within the protein.
 <Structure load='7RSA' size='500' frame='true' align='left' caption='Insert caption here' scene='Sandbox_Reserved_197/Rnase_a_wild_type/4' />