A major factor in the folding of proteins is the burying of hydrophobic side chains. A specific example is the packing of alpha-helices on beta-sheets by interdigitation of nonpolar side chains. The contributions of these interactions to the energetics of protein stability may be measured by simple protein engineering experiments. We have used site-directed mutagenesis to truncate hydrophobic side chains at an alpha-helix/beta-sheet interface in the small ribonuclease from Bacillus amyloliquefaciens (barnase). The decreases in stability of the mutant proteins were measured by their susceptibility to urea denaturation. Creation of a cavity the size of a -CH2-group destabilizes the enzyme by 1.1 kcal mol-1, and a cavity the size of three such groups by 4.0 kcal mol-1. Study holds ProTherm entries: 1959, 1960, 1961, 1962 Extra Details: dG and ddG were measured in the presence of 2.8M urea hydrophobic interactions; barnase; protein stability;,alpha-helices; beta-sheets; protein engineering
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:18 p.m.
|Number of data points||14|
|Proteins||Ribonuclease ; Ribonuclease ; Ribonuclease ; Ribonuclease ; Ribonuclease|
|Assays/Quantities/Protocols||Experimental Assay: Cm pH:6.15 ; Experimental Assay: ddG pH:6.15 ; Experimental Assay: dG_H2O pH:6.15 ; Experimental Assay: ddG pH:6.3 ; Experimental Assay: Cm pH:6.3 ; Experimental Assay: dG_H2O pH:6.3 ; Derived Quantity: ddG_H2O pH:6.15 ; Derived Quantity: ddG_H2O pH:6.3|
|Libraries||Mutations for sequence AQVINTFDGVADYLQTYHKLPDNYITKSEAQALGWVASKGNLADVAPGKSIGGDIFSNREGKLPGKSGRTWREADINYTSGFRNSDRILYSSDWLIYKTTDHYQTFTKIR|