Sulfate anion stabilization of native ribonuclease A both by anion binding and by the Hofmeister effect.


Abstract

Data are reported for T(m), the temperature midpoint of the thermal unfolding curve, of ribonuclease A, versus pH (range 2-9) and salt concentration (range 0-1 M) for two salts, Na(2)SO(4) and NaCl. The results show stabilization by sulfate via anion-specific binding in the concentration range 0-0.1 M and via the Hofmeister effect in the concentration range 0.1-1.0 M. The increase in T(m) caused by anion binding at 0.1 M sulfate is 20 degrees at pH 2 but only 1 degree at pH 9, where the net proton charge on the protein is near 0. The 10 degrees increase in T(m) between 0.1 and 1.0 M Na(2)SO(4), caused by the Hofmeister effect, is independent of pH. A striking property of the NaCl results is the absence of any significant stabilization by 0.1 M NaCl, which indicates that any Debye screening is small. pH-dependent stabilization is produced by 1 M NaCl: the increase in T(m) between 0 and 1.0 M is 14 degrees at pH 2 but only 1 degree at pH 9. The 14 degree increase at pH 2 may result from anion binding or from both binding and Debye screening. Taken together, the results for Na(2)SO(4) and NaCl show that native ribonuclease A is stabilized at low pH in the same manner as molten globule forms of cytochrome c and apomyoglobin, which are stabilized at low pH by low concentrations of sulfate but only by high concentrations of chloride. Study holds ProTherm entries: 15264, 15265, 15266, 15267, 15268, 15269, 15270, 15271, 15272, 15273, 15274, 15275, 15276, 15277, 15278, 15279 Extra Details: Anion-specific binding; protein stabilization; net positive charge; ribonuclease A; thermal unfolding; Hofmeister effect

Submission Details

ID: bkWqjT3B4

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:46 p.m.

Version: 1

Publication Details
Ramos CH;Baldwin RL,Protein Sci. (2002) Sulfate anion stabilization of native ribonuclease A both by anion binding and by the Hofmeister effect. PMID:12070329
Additional Information

Number of data points 48
Proteins Ribonuclease pancreatic ; Ribonuclease pancreatic
Unique complexes 1
Assays/Quantities/Protocols Experimental Assay: Cm ionic:NaSCN: 0.75 M ; Experimental Assay: m ionic:NaSCN: 0.75 M ; Experimental Assay: dG_H2O ionic:NaSCN: 0.75 M ; Experimental Assay: Cm ionic:NaSCN: 0.50 M ; Experimental Assay: m ionic:NaSCN: 0.50 M ; Experimental Assay: dG_H2O ionic:NaSCN: 0.50 M ; Experimental Assay: Cm ionic:NaSCN: 0.25 M ; Experimental Assay: m ionic:NaSCN: 0.25 M ; Experimental Assay: dG_H2O ionic:NaSCN: 0.25 M ; Experimental Assay: Cm ionic:NaSCN: 0.05 M ; Experimental Assay: m ionic:NaSCN: 0.05 M ; Experimental Assay: dG_H2O ionic:NaSCN: 0.05 M ; Experimental Assay: Cm ionic:NaSCN: 0.01 M ; Experimental Assay: m ionic:NaSCN: 0.01 M ; Experimental Assay: dG_H2O ionic:NaSCN: 0.01 M ; Experimental Assay: Cm ionic:Na2SO4: 1.00 M ; Experimental Assay: m ionic:Na2SO4: 1.00 M ; Experimental Assay: dG_H2O ionic:Na2SO4: 1.00 M ; Experimental Assay: Cm ionic:Na2SO4: 0.80 M ; Experimental Assay: m ionic:Na2SO4: 0.80 M ; Experimental Assay: dG_H2O ionic:Na2SO4: 0.80 M ; Experimental Assay: Cm ionic:Na2SO4: 0.50 M ; Experimental Assay: m ionic:Na2SO4: 0.50 M ; Experimental Assay: dG_H2O ionic:Na2SO4: 0.50 M ; Experimental Assay: Cm ionic:Na2SO4: 0.20 M ; Experimental Assay: m ionic:Na2SO4: 0.20 M ; Experimental Assay: dG_H2O ionic:Na2SO4: 0.20 M ; Experimental Assay: Cm ionic:Na2SO4: 0.01 M ; Experimental Assay: m ionic:Na2SO4: 0.01 M ; Experimental Assay: dG_H2O ionic:Na2SO4: 0.01 M ; Experimental Assay: Cm ionic:NaCl: 1.00 M ; Experimental Assay: m ionic:NaCl: 1.00 M ; Experimental Assay: dG_H2O ionic:NaCl: 1.00 M ; Experimental Assay: Cm ionic:NaCl: 0.75 M ; Experimental Assay: m ionic:NaCl: 0.75 M ; Experimental Assay: dG_H2O ionic:NaCl: 0.75 M ; Experimental Assay: Cm ionic:NaCl: 0.50 M ; Experimental Assay: m ionic:NaCl: 0.50 M ; Experimental Assay: dG_H2O ionic:NaCl: 0.50 M ; Experimental Assay: Cm ionic:NaCl: 0.25 M ; Experimental Assay: m ionic:NaCl: 0.25 M ; Experimental Assay: dG_H2O ionic:NaCl: 0.25 M ; Experimental Assay: Cm ionic:NaCl: 0.01 M ; Experimental Assay: m ionic:NaCl: 0.01 M ; Experimental Assay: dG_H2O ionic:NaCl: 0.01 M ; Experimental Assay: Cm ionic:: ; Experimental Assay: m ionic:: ; Experimental Assay: dG_H2O ionic::
Libraries Mutations for sequence KETAAAKFERQHMDSSTSAASSSNYCNQMMKSRNLTKDRCKPVNTFVHESLADVQAVCSQKNVACKNGQTNCYQSYSTMSITDCRETGSSKYPNCAYKTTQANKHIIVACEGNPYVPVHFDASV
Sequence Assay Result Units