Acid stabilization of human growth hormone equilibrium folding intermediates.


Equilibrium denaturation experiments were performed on human growth hormone (hGH) under acidic conditions (pH 1.5-3.0) and different protein concentrations. At 0.1 mg/ml hGH using intrinsic tryptophan fluorescence and far-UV circular dichroism (CD) detection, midpoint values of 4.6 M GdnHCl were observed that are identical to those obtained at neutral pH. However, the delta G values were reduced at pH 2.5 relative to pH 8.0 (10.5 vs. 15 kcal/mol). Increasing the protein concentration to 1 mg/ml resulted in a biphasic denaturation profile by far-UV CD detection at 222 nm, while near-UV CD measurements at 295 nm yielded a cooperative transition with a midpoint value of 3.6 M GdnHCl. These results indicate that equilibrium intermediates having a propensity to aggregate are highly populated under acid conditions. Static light scattering measurements performed under partial unfolding conditions (4.5 M GdnHCl) at pH 2.5 confirmed the existence of a large molecular weight (congruent to 80 kDa) self-associated intermediate. No evidence of aggregation was found for hGH under acid conditions in the absence of denaturant, indicating that self-association results from the formation of an intermediate. Equilibrium GdnHCl concentration-jump experiments confirmed that association only occurs from an intermediate species and not from any other conformational state, and formation of the self-associated intermediate can lead to irreversible loss of protein due to precipitation. These results demonstrate that acid stabilizes equilibrium folding intermediates of hGH. Study holds ProTherm entries: 9361, 9362, 9363, 9364, 9365, 9366, 9367, 9368, 9369 Extra Details: pH; denaturation; intermediates; protein folding;,self-association; growth hormone; (human)

Submission Details

ID: 5ErVsX4B3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:37 p.m.

Version: 1

Publication Details
DeFelippis MR;Kilcomons MA;Lents MP;Youngman KM;Havel HA,Biochim. Biophys. Acta (1995) Acid stabilization of human growth hormone equilibrium folding intermediates. PMID:7873589
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
200.0 B,C Somatotropin P10912 GHR_HUMAN
190.2 B,C Somatotropin Q9XSZ1 GHR_PAPAN
185.4 B,C Somatotropin P79194 GHR_MACMU
181.4 B,C Somatotropin Q95ML5 GHR_SAIBB
100.0 A Somatotropin P01241 SOMA_HUMAN
100.0 A Somatotropin P58756 SOMA_PANTR
96.8 A Somatotropin P33093 SOMA_MACMU
93.7 A Somatotropin P58757 SOM2_PANTR
90.5 A Somatotropin Q9GMB3 SOMA_CALJA
93.2 A Somatotropin P01242 SOM2_HUMAN
90.5 A Somatotropin P58343 SOMA_SAIBB