Sandbox Reserved 197
From Proteopedia
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== '''Introduction''' == | == '''Introduction''' == | ||
| - | Ribonuclease A is an enzyme involved in catalyzing RNA degradation. The structure of RNase A has been determined through crystallization and FABMS. There are several features of its structure that are pertinent to its folding and function. The catalytic residues of RNase A include His12, His 119, and Lys41. The active site lies within its cleft. RNase A has eight cysteine residues present that form four disulfide linkages which contribute to the ordered structure that has been observed as well as the speed of folding. Another important aspect to folding is the presence of two ''cis'' proline residues. | + | Ribonuclease A is an enzyme involved in catalyzing RNA degradation. The structure of RNase A has been determined through crystallization and FABMS. There are several features of its structure that are pertinent to its folding and function. The catalytic residues of RNase A include His12, His 119, and Lys41. The active site lies within its cleft. RNase A has eight cysteine residues present that form four disulfide linkages which contribute to the ordered structure that has been observed as well as the speed of folding. Another important aspect to folding is the presence of two ''cis'' proline residues. There are specific parts of a protein that are required for the folding structure. |
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| + | == '''Folding''' == | ||
| + | '''Proline Conformation''' | ||
| + | Most amino acids found in nature reside in a ''trans'' conformation. Due to their cyclic structure, prolines are more stable in a ''cis'' conformation. RNase A contains four proline residues, two reside in the cis formation and two in the trans formation. RNase A mutants help illustrate the key components in its folding mechanism. | ||
| + | The Tyr92-Pro93 peptide group of RNase A in its native state is found in the ''cis'' conformation. Despite a P93A mutation, a cis conformation still forms; this is an unlikely conformation for an alanine residue. Upon unfolding Tyr92-Ala93 undergoes isomerization to form its favored trans conformation. This points to the fact that this cis bond formation is a key component to the protein structure. Although | ||
| + | '''Disulfide Bonds''' | ||
| + | In RNase A, there are four disulfide bonds present that contribute to the thermal stability and the rate of folding. The residues involved in these linkages include Cys26-Cys84, Cys58-Cys110, Cys40-Cys95, and Cys65-Cys72. Cys26-Cys84 and Cys58-Cys110 create an interaction between an alpha-helix and a beta sheet. This is the main contributor to the thermodynamic stability. | ||
| + | The importance of the disulfide bonds were examined by oxidizing and reducing | ||
Revision as of 17:05, 28 March 2011
÷
| This Sandbox is Reserved from Feb 02, 2011, through Jul 31, 2011 for use by the Biochemistry II class at the Butler University at Indianapolis, IN USA taught by R. Jeremy Johnson. This reservation includes Sandbox Reserved 191 through Sandbox Reserved 200. |
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Introduction
Ribonuclease A is an enzyme involved in catalyzing RNA degradation. The structure of RNase A has been determined through crystallization and FABMS. There are several features of its structure that are pertinent to its folding and function. The catalytic residues of RNase A include His12, His 119, and Lys41. The active site lies within its cleft. RNase A has eight cysteine residues present that form four disulfide linkages which contribute to the ordered structure that has been observed as well as the speed of folding. Another important aspect to folding is the presence of two cis proline residues. There are specific parts of a protein that are required for the folding structure.
Folding
Proline Conformation Most amino acids found in nature reside in a trans conformation. Due to their cyclic structure, prolines are more stable in a cis conformation. RNase A contains four proline residues, two reside in the cis formation and two in the trans formation. RNase A mutants help illustrate the key components in its folding mechanism. The Tyr92-Pro93 peptide group of RNase A in its native state is found in the cis conformation. Despite a P93A mutation, a cis conformation still forms; this is an unlikely conformation for an alanine residue. Upon unfolding Tyr92-Ala93 undergoes isomerization to form its favored trans conformation. This points to the fact that this cis bond formation is a key component to the protein structure. Although Disulfide Bonds In RNase A, there are four disulfide bonds present that contribute to the thermal stability and the rate of folding. The residues involved in these linkages include Cys26-Cys84, Cys58-Cys110, Cys40-Cys95, and Cys65-Cys72. Cys26-Cys84 and Cys58-Cys110 create an interaction between an alpha-helix and a beta sheet. This is the main contributor to the thermodynamic stability. The importance of the disulfide bonds were examined by oxidizing and reducing
