The characterization of eight tyrosine to phenylalanine mutations in ribonuclease SA3 /
An investigation of the contribution of hydrogen bonding to protein stability was performed using Ribonuclease Sa3 as a model system. Ribonuclease Sa3 (RNase Sa3) has eight tyrosine residues. Eight mutants were constructed in which the tyrosines were replaced with phenylalanines. In three of the mut...
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| Format: | Thesis eBook |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2000.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Summary: | An investigation of the contribution of hydrogen bonding to protein stability was performed using Ribonuclease Sa3 as a model system. Ribonuclease Sa3 (RNase Sa3) has eight tyrosine residues. Eight mutants were constructed in which the tyrosines were replaced with phenylalanines. In three of the mutants the tyrosines formed one intramolecular hydrogen bond, three mutants removed an intermolecular hydrogen bond to a water or ion molecule, and two mutants made no apparent hydrogen bonds. Removing an intramolecular hydrogen bond destabilized RNase Sa3 on average 2.1 [] 0.6 kcal mol⁻¹, which agrees well with previously published results. The intermolecular hydrogen bonding mutants contributed much less to stability, only destabilizing the protein by 0.6 [] 0.5 kcal mol⁻¹. The two Tyr[]Phe mutants that made no apparent hydrogen bonds gave variable results, with one mutant being slightly stabilized by 0.5 kcal mol⁻¹, and the other mildly destabilized by 0.6 kcal mol⁻¹. The []([]G) results obtained for the eight Tyr[]Phe mutants in lease Sa3 were compared with data from structurally analogous Tyr[]Phe mutants in lease Sa, a closely related protein. The stability changes are in remarkable agreement when the mutations at similar sites are compared. The results for the Tyr[]Phe mutation that stabilized RNase Sa3 were similar to that seen in RNase Sa. The most notable difference was between RNase Sa Tyr52[]Phe and lease Sa3 Tyr55[]Phe, where the RNase Sa mutant was 1.3 kcal mol⁻¹ more destabilized. |
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| Item Description: | "Major subject: Medical Science". In title numerals are used Vita. |
| Physical Description: | xii, 72 leaves : illustrations ; 28 cm. Also available online. Issued also on microfiche from Lange Micrographics. |
| Bibliography: | Includes bibliographical references (leaves 67-71). |