A protein dissection study demonstrates that two specific hydrophobic clusters play a key role in stabilizing the core structure of the molten globule state of human ?-lactalbumin

Demarest, Stephen J.; Horng, Jia‐Cherng; Raleigh, Daniel P.

doi:10.1002/1097-0134(20010201)42:2<237::aid-prot110>3.0.co;2-b

Cited by 22 publications

(16 citation statements)

References 25 publications

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“…Long-range hydrophobic interactions involving core residues such as Tyr-103 and Trp-26 BLA have been shown to bring the B-and D-helices into close proximity, leading to ready formation of the Cys-28-Cys-111 disulfide bond during oxidative folding and generation of the native fold (38). Similarly, a disulfide-bridged synthetic peptide construct (residues 1-38 and 101-120) containing these two residues displays nativelike signatures in far-UV CD and fluorescence spectra, highlighting the importance of the long-range interactions between Trp-26 BLA and Tyr-103 in stabilizing native-like structure (39). Concerning the protein backbone, well resolved 15 N-1 H HSQC peaks for Tyr-103 and Trp-26 BLA NH protons are observed at only the highest urea concentrations (10 M) in progressive denaturation experiments (35), indicating that the backbone regions of these residues are highly recalcitrant to complete unfolding.…”

Section: Discussionmentioning

confidence: 99%

Multiple subsets of side-chain packing in partially folded states of α-lactalbumins

Mok

Nagashima

Day

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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Photochemically induced dynamic nuclear polarization NMR pulselabeling techniques have been used to obtain detailed information about side-chain surface accessibilities in the partially folded (molten globule) states of bovine and human ␣-lactalbumin prepared under a variety of well defined conditions. Pulse labeling involves generating nuclear polarization in the partially folded state, rapidly refolding the protein within the NMR sample tube, then detecting the polarization in the well dispersed native-state spectrum. Differences in the solvent accessibility of specific side chains in the various molten globule states indicate that the hydrophobic clusters involved in stabilizing the ␣-lactalbumin fold can be formed from interactions between a variety of different hydrophobic residues in both native and nonnative environments. The multiple subsets of hydrophobic clusters are likely to result from the existence of distinct but closely related local minima on the free-energy landscape of the protein and show that the fold and topology of a given protein may be formed from degenerate groups of side chains.hydrophobic cluster ͉ protein folding ͉ pulse labeling ͉ chemically induced dynamic nuclear polarization ͉ molten globule V ery significant advances, both theoretical and experimental, have been made in recent years in elucidating the principles that govern the folding of proteins (1, 2). In particular, the concept of an energy landscape has provided a general framework for interpreting the thermodynamics and kinetics of the folding process through which a polypeptide chain converts from a disorganized unfolded state into the tightly packed native state (N state) at the global energy minimum (3, 4). Recent approaches, involving a combination of computer-simulation techniques with experimental constraints, have enabled three-dimensional structural ensembles of various partially folded species and folding intermediates to be defined and provide a coarse-grained description of the development of interresidue interactions and chain topologies involved in attaining the final native structure (5-7). Of particular importance in this context are compact denatured states, often known as molten globules (MGs), which are commonly characterized by the presence of native-like secondary structure and hydrodynamic radii but lack both native-like packing of the internal amino acid side chains and exclusion of solvent molecules from the hydrophobic core of the protein (8, 9). The detailed experimental description of such states will undoubtedly provide important information about the specific factors stabilizing the overall chain topology at a residue-specific side-chain level (10). However, MG states are very difficult to characterize by using conventional x-ray crystallography or NMR techniques because of their heterogeneous character (11,12).We have recently developed NMR techniques to characterize aromatic side chains in transient, kinetic intermediate species present in real-time protein folding experiments (13, 14) or in p...

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Section: Discussionmentioning

confidence: 99%

Multiple subsets of side-chain packing in partially folded states of α-lactalbumins

Mok

Nagashima

Day

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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“…The molten globule states of several model proteins including apomyoglobin, 11,12,21,34-41 lysozome, 14,42-46 a-lactabulmin, 10,11,[15][16][17]20,22,23,30,32,[47][48][49][50][51] and cytochrome c, 52-54 have served as the prototype of protein folding intermediates and extensive studies have been dedicated to their structural, Mechanism of the pH-induced Unfolding of CHABII thermodynamic, kinetic and theoretical aspects. In general, many proteins adopted molten globule states under medium denaturing conditions, in particular at acidic pH.…”

Section: Discussionmentioning

confidence: 99%

Molecular Mechanism Underlying the Thermal Stability and pH-induced Unfolding of CHABII

Zheng

Song

2005

Journal of Molecular Biology

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“…36 -38 Peptides encompassing residues 101-111 and 101-120 of the a-LA sequence do show some degree of helicity in aqueous solution but the latter appears to be largely non-native in character. 39,40 A peptide consisting of residues 1 -38 and 95 -120 cross-linked by the C28 -C111 disulfide bond, however, shows not only significant helical structure but also characteristics of a molten globule including the enhancement of ANS fluorescence. 41 Deletion of residues 95 -100 has little effect on the structure in this peptide, indicating that the C-helix is not important for the stability of its molten globule structure.…”

Section: Discussionmentioning

confidence: 99%

Local and Global Cooperativity in the Human α-Lactalbumin Molten Globule

Quezada¹,

Schulman²,

Froggatt³

et al. 2004

Journal of Molecular Biology

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A protein dissection study demonstrates that two specific hydrophobic clusters play a key role in stabilizing the core structure of the molten globule state of human ?-lactalbumin

Cited by 22 publications

References 25 publications

Multiple subsets of side-chain packing in partially folded states of α-lactalbumins

Multiple subsets of side-chain packing in partially folded states of α-lactalbumins

Molecular Mechanism Underlying the Thermal Stability and pH-induced Unfolding of CHABII

Local and Global Cooperativity in the Human α-Lactalbumin Molten Globule

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