Distinct stability of recombinant L and H subunits of human ferritin: calorimetric and ANS binding studies.


Thermodynamic and pH stability of recombinant human L- and H-ferritins were probed by differential scanning calorimetry and 8-anilino-1-naphthalenesulfonate (ANS) binding in the pH range 2-7. At pH 2.0-2.8 they were dissociated into subunit monomers and in this pH interval the H-subunit displayed a single calorimetrically-revealed domain with properties of a molten globule-like state: low enthalpy (6.3-8.0 J/g or 169-172 kJ/mol) and Tm of thermal unfolding (approximately 50 degrees C), a wide transition range (approximately 20 degrees C) and high ANS binding. In contrast, at pH 2 the L-ferritin subunit showed two calorimetric domains with Tm of 35 and 40 degrees C with similar unfolding enthalpies and with moderate extent of interactions, as indicated by the ratio of calorimetric enthalpy (293.9 kJ/mol) and van't Hoff enthalpy (174.2 kJ/mol) for the thermal transition. A pH increase from 2.0 to 2.8 determined the coupling of the two domains into a single cooperative folding unit and drastic increase of the transition temperature (from 37 to 80 degrees C). The contacts between the two domains in the L-subunit appeared to contribute to about 30% of the total stabilization free energy. The unfolding enthalpies, heat capacity changes and pronounced ANS binding of the L-subunit at pH 2.0-2.8 indicated that part of the structure lacked 'meltable' tertiary interactions. The results indicate that H- and L-subunits are stabilized by largely different intra-chain interactions with a critical contribution to L-subunit stability of embedded salt bridge(s) absent in the H-subunit. Study holds ProTherm entries: 3456, 3457, 3458, 3459, 3460, 3461, 3462 Extra Details: differential scanning calorimetry; ferritin subunits;,protein folding; protein stability

Submission Details

ID: atuxeD5Q4

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:21 p.m.

Version: 1

Publication Details
Martsev SP;Vlasov AP;Arosio P,Protein Eng. (1998) Distinct stability of recombinant L and H subunits of human ferritin: calorimetric and ANS binding studies. PMID:9681870
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 Ferritin light chain P02792 FRIL_HUMAN
98.9 Ferritin light chain Q5R538 FRIL_PONAB
99.5 Ferritin heavy chain P02794 FRIH_HUMAN
98.9 Ferritin heavy chain Q5R8J7 FRIH_PONAB
95.6 Ferritin heavy chain Q9XT73 FRIH_TRIVU
95.6 Ferritin heavy chain Q95MP7 FRIH_CANLF
94.5 Ferritin heavy chain Q2MHN2 FRIH_FELCA
93.4 Ferritin heavy chain P29389 FRIH_CRIGR
94.4 Ferritin heavy chain P19132 FRIH_RAT
92.2 Ferritin heavy chain Q8MIP0 FRIH_HORSE
92.8 Ferritin heavy chain P09528 FRIH_MOUSE
90.6 Ferritin heavy chain O46414 FRIH_BOVIN
92.6 Ferritin heavy chain P08267 FRIH_CHICK
95.7 Ferritin heavy chain P25915 FRIH_RABIT
92.5 Ferritin heavy chain P18685 FRIH_SHEEP