Contribution of chain termini to the conformational stability and biological activity of onconase.


Onconase, a member of the RNase A superfamily, is a potent antitumor agent which is undergoing phase III clinical trials as an antitumor drug. We have recently shown that onconase is an unusually stable protein. Furthermore, the protein is resistant to the action of proteases, which could influence its use as a drug, prolonging its biological life, and leading to its renal toxicity. Our investigation focused on the contribution of chain termini to onconase conformational stability and biological activities. We used differential scanning calorimetry, isothermal unfolding experiments, limited proteolysis, and catalytic and antitumor activity determinations to investigate the effect of the elimination of the two blocks at the chain termini, the N-terminal cyclized glutamine and the C-terminal disulfide bridge between the terminal Cys104 and Cys87. The determination of the thermodynamic parameters of the protein led to the conclusion that the two blocks at onconase chain termini are responsible for the unusual stability of the protein. Moreover, the reduced stability of the onconase mutants does not influence greatly their catalytic and antitumor activities. Thus, our data would suggest that an onconase-based drug, with a decreased toxicity, could be obtained through the use of less stable onconase variants. Study holds ProTherm entries: 11751 Extra Details: potent antitumor agent; renal toxicity; activity; catalytic

Submission Details

ID: 2zKqxyY5

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:43 p.m.

Version: 1

Publication Details
Notomista E;Catanzano F;Graziano G;Di Gaetano S;Barone G;Di Donato A,Biochemistry (2001) Contribution of chain termini to the conformational stability and biological activity of onconase. PMID:11478876
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 PDB Entries

Structure ID Release Date Resolution Structure Title
1PU3 2003-06-24T00:00:00+0000 0 The Solution NMR Structure and Dynamics of a Recombinant Onconase with Altered N-terminal and Met23 residues
1YV4 2005-02-15T00:00:00+0000 1.51 X-ray structure of M23L onconase at 100K
1YV6 2005-02-15T00:00:00+0000 1.78 X-ray structure of M23L onconase at 298K
1YV7 2005-02-15T00:00:00+0000 1.9 X-ray structure of (C87S,des103-104) onconase
2GMK 2006-04-06T00:00:00+0000 1.65 Crystal structure of onconase double mutant with spontaneously-assembled (AMP) 4 stack
2I5S 2006-08-25T00:00:00+0000 1.9 Crystal structure of onconase with bound nucleic acid
2KB6 2008-11-21T00:00:00+0000 0 Solution structure of onconase C87A/C104A
2LT5 2012-05-14T00:00:00+0000 0 Zymogen-FLG of the onconase
3FD7 2008-11-25T00:00:00+0000 1.53 Crystal structure of Onconase C87A/C104A-ONC

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Protein P-30 P22069 RNP30_LITPI