Three-state analysis of sperm whale apomyoglobin folding.


We give a quantitative description of the urea- and acid-induced transitions of apomyoglobin at 0 degree C and 2 mM sodium citrate. Our data consist of two series of unfolding curves: (1) acid-induced unfolding carried out in the presence of various concentrations of urea and (2) urea-induced unfolding at various pH values. A three-state equation is derived which relates the stability of three different conformations of apomyoglobin (native [N], unfolded [U], and intermediate [I]) as a function of urea and of pH. This equation fits our data reasonably well. The parameters which give the best fit have both thermodynamic and structural implications for N, I, and U. Specifically, I is closer in Gibbs energy to U than to N, indicating that side-chain packing results in much of the stability of native protein structure. The equilibria between N and I and between I and U are equally sensitive to urea, suggesting that much of the surface of I is inaccessible to solvent. The acid-induced transition in which N unfolds can be described as the result of titration of approximately two histidines with low pKaS in N. Under physiological conditions (neutral pH, no urea) I is the most stable non-native conformation. Study holds ProTherm entries: 4545, 4546 Extra Details: transition is from native to intermediate

Submission Details


Submitter: Connie Wang

Submission Date: April 24, 2018, 8:26 p.m.

Version: 1

Publication Details
Barrick D;Baldwin RL,Biochemistry (1993) Three-state analysis of sperm whale apomyoglobin folding. PMID:8466917
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
6BMG 2017-11-14T00:00:00+0000 1.88 Structure of Recombinant Dwarf Sperm Whale Myoglobin (Oxy)
5YCI 2017-09-07T00:00:00+0000 1.97 Ancestral myoglobin aMbWb' of Basilosaurus relative (polyphyly)
5YCJ 2017-09-07T00:00:00+0000 1.58 Ancestral myoglobin aMbWb' of Basilosaurus relative (polyphyly) imidazole-ligand
101M 1997-12-13T00:00:00+0000 2.07 SPERM WHALE MYOGLOBIN F46V N-BUTYL ISOCYANIDE AT PH 9.0
102M 1997-12-15T00:00:00+0000 1.84 SPERM WHALE MYOGLOBIN H64A AQUOMET AT PH 9.0
103M 1997-12-16T00:00:00+0000 2.07 SPERM WHALE MYOGLOBIN H64A N-BUTYL ISOCYANIDE AT PH 9.0
104M 1997-12-18T00:00:00+0000 1.71 SPERM WHALE MYOGLOBIN N-BUTYL ISOCYANIDE AT PH 7.0
105M 1997-12-18T00:00:00+0000 2.02 SPERM WHALE MYOGLOBIN N-BUTYL ISOCYANIDE AT PH 9.0
106M 1997-12-21T00:00:00+0000 1.99 SPERM WHALE MYOGLOBIN V68F ETHYL ISOCYANIDE AT PH 9.0
107M 1997-12-22T00:00:00+0000 2.09 SPERM WHALE MYOGLOBIN V68F N-BUTYL ISOCYANIDE AT PH 9.0

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
90.1 Myoglobin P02182 MYG_ZIPCA
90.1 Myoglobin Q0KIY0 MYG_MESST
90.1 Myoglobin P02183 MYG_MESCA
90.3 Myoglobin P02180 MYG_BALPH
90.9 Myoglobin P02179 MYG_BALAC
90.8 Myoglobin P68278 MYG_PHOPH
90.8 Myoglobin P68277 MYG_PHODA
90.8 Myoglobin P68279 MYG_TURTR
90.8 Myoglobin P68276 MYG_DELDE
90.8 Myoglobin Q0KIY7 MYG1_STEAT
91.4 Myoglobin P02173 MYG_ORCOR
92.1 Myoglobin P02174 MYG_GLOME
91.4 Myoglobin P02181 MYG_INIGE
92.2 Myoglobin P02178 MYG_MEGNO
91.4 Myoglobin Q0KIY3 MYG_PENEL
92.9 Myoglobin P02177 MYG_ESCRO
92.9 Myoglobin Q0KIY2 MYG_BALED
92.9 Myoglobin Q0KIY1 MYG_BALBO
96.8 Myoglobin P02184 MYG_KOGSI
96.8 Myoglobin Q0KIY5 MYG_KOGBR
100.0 Myoglobin P02185 MYG_PHYMC