Thermodynamic stability of the two isoforms of bovine seminal ribonuclease.


Bovine seminal ribonuclease (BS-RNase) is a dimeric protein with two identical subunits linked by two disulfide bridges, each subunit showing 80% of sequence identity with pancreatic RNase A. BS-RNase exists in two different quaternary conformations in solution: the MxM form, in which each subunit exchanges its alpha-helical N-terminal segment with its partner, and the M=M form with no exchange. By differential scanning microcalorimetry (DSC), the denaturation of the two dimeric forms of BS-RNase was found to be more complex than a simple two-state process. Monomeric derivatives of the dimeric protein follow instead a simple two-state mechanism, but are distinctly less stable than RNase A. The three-state N if I if D denaturation process of the two quaternary isoforms was interpreted by identifying in the dimers a central highly structured core, enclosing the covalently bonded subunit interface, which unfolds only after the periphery (mainly the N-terminal peptide) unfolds. Circular dichroism spectra of the two forms in the far-ultraviolet region show large differences between the secondary structure of the isoforms and that of the native BS-RNase mixture at equilibrium. This has been attributed to the presence in the equilibrium mixture of intermediate forms with displaced and disordered N-terminal alpha-helical segments. Study holds ProTherm entries: 8307, 8308 Extra Details: disulfide bridges; dimeric forms; secondary structure;,alpha-helical segments

Submission Details

ID: Kb2Wb8FM4

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:35 p.m.

Version: 1

Publication Details
Giancola C;Del Vecchio P;De Lorenzo C;Barone R;Piccoli R;D'Alessio G;Barone G,Biochemistry (2000) Thermodynamic stability of the two isoforms of bovine seminal ribonuclease. PMID:10891077
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Seminal ribonuclease P00669 RNS_BOVIN