Lysozyme and α-Lactalbumin: Structure, Function, and Interrelationships

McKenzie, H.A.; White, Frederick H.

doi:10.1016/s0065-3233(08)60198-9

Cited by 228 publications

(156 citation statements)

References 459 publications

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“…The WT side chain, Arg, is exposed to solvent with its side chain parallel to that of Phe 34. Residue I 14 is usually occupied by Arg or His, whereas Phe, Tyr, or Trp are found at position 34 in most C-type lysozymes (McKenzie & White, 1991). The R114H mutation in the chicken enzyme yields a 1.8 "C increase in T,.…”

Section: Side-chain Interaction Between Residues I14 and 34mentioning

confidence: 99%

Design and structural analysis of an engineered thermostable chicken lysozyme

Shih

Kirsch

1995

Protein Science

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A hyperstable (hs) variant of chicken egg-white lysozyme with enhanced thermal (AT, = + 10.5 "C) and chemical (AC,n for guanidine hydrochloride denaturation = + 1.3 M) stabilities relative to wild-type (WT) was constructed by combining several individual stabilizing substitutions. The free energy difference between the native and denatured states of the hs variant is 3.1 (GdnHCl, 25 "C) to 4.0 (differential scanning calorimetry, 74 "C) kcal mol" greater than that of WT. The specific activity of the hs variant is 2.5-fold greater than that of WT. The choice of mutations came from diverse sources: (1) The 155L/S91T core construct with AT, = 3.3 "C from WT was available from the accompanying study (Shih P, Holland DR, Kirsch JF, 1995, Protein Sci 4:2050-2062. (2) The A31V mutation was suggested by the better atomic packing in the human lysozyme structure where the Ala 3 1 equivalent is Leu. (3) The H15L and R114H substitutions were selected on the basis of sequence comparisons with pheasant lysozymes that are more stable than the chicken enzyme. (4) The DlOlS variant was identified from a screen of mutants previously prepared in this laboratory. The effects of the individual mutations on stability are cumulative and nearly additive.Keywords: a-helix propensity; avian lysozyme sequences; chicken lysozyme; human lysozyme; interior packing; protein design; structures; thermodynamic stability A challenging goal of protein engineering is the design of proteins with significantly enhanced thermo-and chemical stabilities. A variety of successful routes to this objective has been undertaken. These include: (1) introducing disulfide bridges (Matsumura et al., 1989b); (2) increasing internal hydrophobic packing (Malcolm et al., 1990); (3) reducing solvent-exposed nonpolar surface area (Pakula & Sauer, 1990); (4) incorporating a metal association site (Kuroki et al., 1989); and (5) adding charged side chains to interact with the a-helix dipoles (Nicholson et al., 1988). However, the above strategies are not always successful and their pursuit has often yielded proteins that are less stable than the WT progenitors for reasons that are not fully understood (e.g., Karpusas et al., 1989;Matsumura et al., 1989a;Eijsink et al., 1992;Leontiev et al., 1993 Abbreviations: hs, a hyperstable variant of chicken lysozyme; GdnHCI, guanidine hydrochloride; T,, the midpoint temperature of the thermal denaturation transition; C,, the midpoint concentration of the GdnHCl denaturation profile; DSC, differential scanning calorimetry; AH,,,, calorimetrically determined enthalpy of denaturation; AC,, the difference between the heat capacities of the native and the denatured states; WT or wt, wild type.

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Section: Side-chain Interaction Between Residues I14 and 34mentioning

confidence: 99%

Design and structural analysis of an engineered thermostable chicken lysozyme

Shih

Kirsch

1995

Protein Science

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“…sharing similar primary, secondary, and tertiary structures (Brew et al, 1967;Browne et al, 1969;Stuart et al, 1986;Acharya et al, 1989Acharya et al, , 1991. Although it is generally accepted that a-LA evolved from C-type lysozyme, its function, i.e., in lactose synthesis, is clearly distinct from the lytic activity of its ancestral protein (McKenzie & White, 1991). Native a-LA is typically isolated with stoichiometric levels of calcium bound at a unique, strong Ca2+-binding loop that has been observed in all crystal structures of a-LA reported to date, but this structural feature is absent in most C-type lysozymes (Hiraoka et al, 1980;Stuart et al, 1986;Acharya et al, 1989Acharya et al, , 1991.…”

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confidence: 99%

Membrane‐bound states of α‐lactalbumin: Implications for the protein stability and conformation

1996

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Abstracta-Lactalbumin (a-LA) associates with dimyristoylphosphatidylcholine (DMPC) or egg lecithin (EPC) liposomes. Thermal denaturation of isolated DMPC or EPC a-LA complexes was dependent on the metal bound state of the protein. The intrinsic fluorescence of thermally denatured DMPC-a-LA was sensitive to two thermal transitions: the T,. of the lipid vesicles, and the denaturation of the protein. Quenching experiments suggested that tryptophan accessibility increased upon protein-DMPC association, in contrast with earlier suggestions that the limited emission red shift upon association with the liposome was due to partial insertion of tryptophan into the apolar phase of the bilayer (Hanssens I et al., 1985, Biochim Biophys Acta 817:154-166). On the other hand, above the protein transition (70 "C), the spectral blue shifts and reduced accessibility to quencher suggested that tryptophan interacts significantly with the apolar phase of either DMPC and EPC. At pH 2, where the protein inserts into the bilayer rapidly, the isolated DMPC-a-LA complex showed a distinct fluorescence thermal transition between 40 and 60 "C, consistent with a partially inserted form that possesses some degree of tertiary structure and unfolds cooperatively. This result is significant in light of earlier findings of increased helicity for the acid form, i.e., molten globule state of the protein (Hanssens I et al., 1985, Biochim Biophys Acta 812154-166). These results suggest a model where a limited expansion of conformation occurs upon association with the membrane at neutral pH and physiological temperatures, with a concomitant increase in the exposure of tryptophan to external quenchers; i.e., the current data do not support a model where an apolar, tryptophan-containing surface is covered by the lipid phase of the bilayer.

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“…Especially the recent identification of the ubiquity of intrinsically disordered proteins (29,30) raises the possibility that the protein structures at the time of gene duplication and speciation were not so rigid as has usually been considered normal for the existing natural proteins. Coevolution of function and structure under slightly different selection pressures acting on a protein family with such disordered structures would lead to the examples of the present-day proteins with similar native structures but with partially different folding cores (7,(31)(32)(33). It should be also noted that the frequent involvement of the functionally important site in folding cores (8,21,22) can be interpreted as a natural consequence of the functional selection in which the structure around the functional site is early developed in the evolutionary history.…”

Section: Resultsmentioning

confidence: 99%

Correlation between evolutionary structural development and protein folding

Nagao

Terada

Yomo

et al. 2005

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

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Evolution should have played important roles in determining folding mechanisms and structures of proteins. In this article we discuss how the folding mechanisms had been affected by the early stage of evolution through which the uniqueness of structure had developed. Although the process of such early-time evolution has remained a mystery, a plausible scenario is that the evolution of proteins toward the ordered structures was guided by functional selection pressure as demonstrated in vitro and in silico. We examine the in silico functional selection of sequences and show that there is a significant correlation between two different processes toward the unique 3D structure, the evolutionary development of structure through sequence selection, and the folding process of the resultant sequence. This finding could be rephrased as protein folding recapitulates the emergence of topology in the molecular evolution. The correlation suggests a guideline for engineering foldable proteins.functional selection ͉ molecular evolution ͉ superfunnel ͉ folding mechanism ͉ energy landscape E rnst Haeckel's statement that ontogeny recapitulates phylogeny, or the embryonic developmental process is a repeat of the evolutionary process, has been a subject of intense intellectual argument since the 19th century (1). Although his claim has been regarded as incorrect in its literal sense, comparison of the developmental process and the evolutionary history has been productive as witnessed in the recent advancement in evolutionary developmental biology or ''evo-devo.'' The early stages of development are typically conserved among the evolutionarily related species, whereas the later stages tend to differ (2-4). Such a correlation between the developmental and evolutionary processes should be based on the bottom-up features of these structure formation processes, which are typical in natural organisms but are rare in artifacts. Both processes share the feature that the cumulative effects of small modifications in the local rules within each cell and between cells progressively brings about the intricate balance among the local rules found within the present-day organisms.Here, we should point out that such local and cumulative features of the structural organization are not limited to embryonic development but are ubiquitous in cellular and molecular biological structural formation processes. In this article, we take protein folding as an example of such a biological structure formation process. Proteins fold to unique native structures according to the evolutionarily designed interactions among amino acid residues. Again, both the folding process and the evolutionary changes of sequences are cumulative processes of local changes, and thus we may be able to expect the correlation between these processes. The intrinsic relationships between the evolutionary history and the folding mechanisms have been suggested by the similarities and differences among folding mechanisms of multiple proteins (5-9). Amino acid sequence is conserved at the ...

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Lysozyme and α-Lactalbumin: Structure, Function, and Interrelationships

Cited by 228 publications

References 459 publications

Design and structural analysis of an engineered thermostable chicken lysozyme

Design and structural analysis of an engineered thermostable chicken lysozyme

Membrane‐bound states of α‐lactalbumin: Implications for the protein stability and conformation

Correlation between evolutionary structural development and protein folding

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