'Noncooperative formation of the off-pathway molten globule during folding of the a-ß parallel protein apoflavodoxin'
| Autor: | Adrie H. Westphal, C.P.M. van Mierlo, Sanne M. Nabuurs |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
Protein Denaturation
Protein Folding Flavodoxin Membrane transport and intracellular motility [NCMLS 5] Biochemie Biochemistry Catalysis Protein Structure Secondary Colloid and Surface Chemistry different denaturants intermediate nmr-spectroscopy Side chain Native state hydrogen-exchange Cysteine Conformational isomerism Protein secondary structure Nuclear Magnetic Resonance Biomolecular Renal disorder [IGMD 9] VLAG Azotobacter vinelandii Alanine biology Chemistry energy landscape on-pathway unfolded molecules Energy landscape General Chemistry Molten globule Random coil transition-state Crystallography Kinetics Amino Acid Substitution biology.protein Thermodynamics structural-characterization Apoproteins azotobacter-vinelandii apoflavodoxin |
| Zdroj: | Journal of the American Chemical Society, 131(7), 2739-2746 Journal of the American Chemical Society, 131, 2739-46 Journal of the American Chemical Society 131 (2009) 7 Journal of the American Chemical Society, 131, 7, pp. 2739-46 |
| ISSN: | 0002-7863 |
| Popis: | Item does not contain fulltext During folding of many proteins, molten globules are formed. These partially folded forms of proteins have a substantial amount of secondary structure but lack virtually all tertiary side-chain packing characteristic of native structures. Molten globules are ensembles of interconverting conformers and are prone to aggregation, which can have detrimental effects on organisms. Consequently, molten globules attract considerable attention. The molten globule that is observed during folding of flavodoxin from Azotobacter vinelandii is a kinetically off-pathway species, as it has to unfold before the native state of the protein can be formed. This intermediate contains helices and can be populated at equilibrium using guanidinium hydrochloride as denaturant, allowing the use of NMR spectroscopy to follow molten globule formation at the residue level. Here, we track changes in chemical shifts of backbone amides, as well as disappearance of resonances of unfolded apoflavodoxin, upon decreasing denaturant concentration. Analysis of the data shows that structure formation within virtually all parts of the unfolded protein precedes folding to the molten globule state. This folding transition is noncooperative and involves a series of distinct transitions. Four structured elements in unfolded apoflavodoxin transiently interact and subsequently form the ordered core of the molten globule. Although hydrophobic, tryptophan side chains are not involved in the latter process. This ordered core is gradually extended upon decreasing denaturant concentration, but part of apoflavodoxin's molten globule remains random coil in the denaturant range investigated. The results presented here, together with those reported on the molten globule of alpha-lactalbumin, show that helical molten globules apparently fold in a noncooperative manner. |
| Databáze: | OpenAIRE |
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