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PubMed1997

Xyloglucan sidechains modulate binding to cellulose during in vitro binding assays as predicted by conformational dynamics simulations.

Cross-links between cellulose microfibrils and xyloglucan (XG) molecules play a major role in defining the structural properties of plant cell walls and the regulation of growth and development of dicotyledonous plants. How these cross-links are established and how they are regulated has yet to be determined. In a previous study, preliminary data were presented which suggested that the different sidechains of XG may play a role in controlling cellulose microfibril-XG interactions. In this study, this question is addressed directly by analyzing to what extent the different sidechains of pea cell wall XG and nasturtium seed storage XG affect their binding to cellulose microfibrils. Of particular importance to this study are the chemical data indicating that pea XG possesses a trisaccharide sidechain, which is not found in nasturtium XG. To this end, conformational dynamic simulations have been used to predict whether oligosaccharides representative of pea and nasturtium XG can adopt a hypothesized cellulose-binding conformation and which of these XGs exhibits a preferential ability to bind cellulose. Extensive analysis of the conformational forms populated during 300 K and high-temperature Monte Carlo simulations established that a planar, sterically accessible, glucan backbone is essential for optimal cellulose-binding. For the trisaccharide sidechain-containing oligosaccharide as found in pea XG, sidechain orientation appeared to regulate the gradual acquisition of this hypothesized cellulose binding conformation. Thus, conformational forms were identified that included the twisted backbone (non-planar) putative solution form of XG, forms in which the trisaccharide sidechain orientation enables increased backbone planarity and steric accessibility, and finally a planar, sterically accessible, backbone. By applying these conformational requirements for cellulose binding, it has been determined that pea XG possesses a two- to threefold occurrence of the cellulose binding conformation than nasturtium XG. Based on this finding, it was predicted that pea XG would bind to cellulose at a higher rate than nasturtium XG. In vitro binding assays showed that pea XG-avicel binding does indeed occur at a twofold higher rate than nasturtium XG-avicel binding. The enhanced ability of pea cell wall XG over nasturtium seed storage XG to associate with cellulose is consistent with a structural role of the former during epicotyl growth where efficient association with cellulose is a requirement. In contrast, the relatively low ability of nasturtium XG to bind cellulose is consistent with the need to enhance the accessibility of this polymer to glycanases during germination. These findings suggest potential roles for XG sidechain substitution, enabling XG to function in a variety of different biological contexts.

Binding Sites↗
PubMed2004

Ultrafast conformational dynamics in cyclic azobenzene peptides of increased flexibility.

Structural changes of peptides containing the azobenzene dye 4-aminomethyl-phenylazobenzoic acid (AMPB) are studied with ultrafast spectroscopy. AMPB peptides are a new class of molecules where the photoisomerizable dye azobenzene is linked to the peptide moiety via a flexible methylene spacer. The ultrafast reactions in the femtosecond to nanosecond time domain are investigated for the optical switch AMPB, a linear and cyclic octapeptide, and a bicyclic octapeptide containing an additional disulfide bridge. These molecules with increasing conformational constraints are studied for the cis to trans and the trans to cis photoreactions. For the cis to trans reaction the isomerization of the chromophore occurs fast in the 1-ps range, whereas it is slower (10-ps range) in the trans to cis reaction. In all peptides the structural changes of the chromophore lead to modifications in the peptide structure in the 10-ps-1-ns time range. The results indicate that the chromophore AMPB acts simultaneously as a fast molecular switch and as a sensor for initial conformational dynamics in the peptide. Experiments in the mid-infrared range where the structural changes of the peptide backbone are directly observed demonstrate that the essential part of the structural dynamics in the bicyclic AMPB peptide occurs faster than 10 ns.

Amino Acid Sequence↗
PubMed2002

Synthesis and conformational dynamics of tricyclic pyridones containing a fused seven-membered ring.

A new synthetic approach to tricyclic pyridones bearing a fused seven-membered ring is described. These compounds exhibit atropisomerism and exist in enantiomeric forms. Chiral HPLC separation of the enantiomers has allowed the rates of racemization to be measured and hence the free energy barrier for flipping the seven-membered ring to be deduced. Introduction of a further element of planar chirality leads to diastereomeric atropisomerism. The rate of interconversion of the diastereomers has been quantified by 2D EXSY NMR spectroscopy allowing a full description of the conformational dynamics of the system.

Algorithms↗
PubMed2005

pH driven conformational dynamics and dimer-to-monomer transition in DLC8.

Dynein light chain protein, a part of the cytoplasmic motor assembly, is a homodimer at physiological pH and dissociates below pH 4.5 to a monomer. The dimer binds to a variety of cargo, whereas the monomer does not bind any of the target proteins. We report here the pH induced stepwise structural and motional changes in the protein, as derived from line broadening and 15N transverse relaxation measurements. At pH 7 and below until 5, partial protonation and consequent interconversion between molecules carrying protonated and neutral histidines, causes conformational dynamics in the dimeric protein and this increases with decreasing pH. Enhanced dynamics in turn leads to partial loosening of the structure. This would have implications for different efficacies of binding by target proteins due to small variations in pH in different parts of the cell, and hence for cargo trafficking from one part to another. Below pH 5, enhanced charge repulsions, partial loss of hydrophobic interactions, and destabilization of H-bonds across the dimer interface cause further loosening of the dimeric structure, leading eventually to the dissociation of the dimer.

Animals↗
PubMed2005

The conformationally dynamic C helix of the RIalpha subunit of protein kinase A mediates isoform-specific domain reorganization upon C subunit binding.

Different isoforms of the full-length protein kinase A (PKA) regulatory subunit homodimer (R2) and the catalytic (C) subunit-bound holoenzyme (R2C2) have very different global structures despite similar molecular weights and domain organization within their primary sequences. To date, it has been the linker sequence between the R subunit dimerization/docking domain and cAMP-binding domain A that has been implicated in modulating domain interactions to give rise to these differences in global structure. The small angle solution scattering data presented here for three different isoforms of PKA heterodimer (deltaR-C) complexes reveal a role for another conformationally dynamic sequence in modulating inter-subunit and domain interactions, the C helix that connects the cAMP-binding domains A and B of the R subunit. The deltaR-C heterodimer complexes studied here were each formed with a monomeric N-terminal deletion mutant of the R subunit (deltaR) that contains the inhibitor sequence and both cAMP-binding domains. The scattering data show that type IIalpha and type IIbeta deltaR-C heterodimers are relatively compact and globular, with the C subunit contacting the inhibitor sequence and both cAMP-binding domains. In contrast, the type Ialpha heterodimer is significantly more extended, with the C subunit interacting with the inhibitor sequence and cAMP-binding domain A, whereas domain B extends out such that its surface is almost completely solvent exposed. These data implicate the C helix of RIalpha in modulating isoform-specific interdomain communication in the PKA holoenzyme, adding another layer of structural complexity to our understanding of signaling dynamics in this multisubunit, multidomain protein kinase.

Animals↗
PubMed2005

Conformational dynamics of complementarity-determining region H3 of an anti-dansyl Fv fragment in the presence of its hapten.

Antigen-induced structural changes in the Fv fragment of an anti-dansyl immunoglobulin G were studied by X-ray crystallography and stopped-flow fluorescence measurement. The crystal structure of the Fv fragment complexed with dansyl-lysine was determined at a resolution of 1.85 A. The dansyl-lysine molecule bound to a narrow cavity formed by the complementarity-determining regions H3 and H1, the N-terminal region of the VH domain and L2 of the VL domain. The structure of the binding site in the crystal structure explained well the results of the previous nuclear magnetic resonance measurements. The hapten binding caused remarkable conformational changes in H3 and its environmental structures, including the hydration structure from those observed in the unliganded state. The tip of H3 moved about 12 A from its position in the unliganded state. In addition, because of the contacts of H3 with the VL domain at the domain interface, the conformational changes of H3 resulted in the relative rotation of the variable domains by 5 degrees from their association observed in the unliganded state. The hydrophobic interactions at the domain interface seemed to be particularly important for the mutual rotation of the domains. The stopped-flow fluorescence measurement monitoring the interaction of the dansyl group and the binding pocket revealed that H3 was in a conformational equilibrium of three consecutive conformational states in the presence of dansyl-lysine in solution; an unliganded state preventing the access of the hapten, another unliganded state able to bind the hapten and the complex. The conformational dynamics of H3 in recognizing and binding the hapten molecule are discussed on the basis of the structural information from the present and previous studies.

Binding Sites↗
PubMed1991

[Modification of nucleic acids by reactive oligonucleotide derivatives having a 5'-terminal nitrogen yperite residue, covalently bound with linkers of varying length. Conformation dynamics of group reactivity in complementary complexes].

By optimizing the length of a linker bearing 5'-terminal alkylating 4-[methyl-(2-chloroethyl)amino]benzylphosphoramide residue, a reactive oligodeoxyribonucleotide derivative has been constructed with an optimal ability to alkylate nucleic bases in a double-stranded region of the complementary complex between a target NA and the addressed oligonucleotide. A such oligonucleotide could be useful for modifying the target NA if the nucleophilic sites of its single-stranded 3'-terminal region are protected due to a specific tertiary structure. A molecular mechanical modelling suggested that the insertion of two additional methylene groups into the standard linker provides an optimal increase in the efficiency of the modification of the base sites exposed into the major groove of the complementary complex. Synthesis of an oligonucleotide derivative with the modified linker and experiments on the target alkylation showed a 2-3 fold increase of the modifying ability as compared with the reagent having the standard linker. The conformational dynamics of the reactive group is discussed.

Alkylation↗
PubMed2005

Dynamic conformational changes of extracellular S5-P linkers in the hERG channel.

The hERG channel has an unusually long 'S5-P linker' (residues 571-613) that lines the outer mouth of the pore. Previously, we have shown that residues along this S5-P linker are critical for the fast-inactivation process and K(+) selectivity of the hERG channel. Here we used several approaches to probe the structure of this S5-P linker and its interactions with other domains of the hERG channel. Circular dichroism and NMR analysis of a synthetic hERG S5-P linker peptide suggested that this linker is quite dynamic: its central region (positions 583-593) can be unstructured or helical, depending on whether it is immersed in an aqueous phase or in contact with a hydrophobic environment. Cysteine introduced into positions 583-597 of the S5-P linker can form intersubunit disulphide bonds, and at least four of them (at 584, 585, 588 and 589) can form disulphide bonds with counterparts from neighbouring subunits. We propose that the four S5-P linkers in a hERG channel can engage in dynamic conformational changes during channel gating, and interactions between S5-P linkers from neighbouring subunits contribute importantly to channel inactivation.

Amino Acid Sequence↗
PubMedDate not supplied

[Analysis of kinetic isotope effects in H2O-D2O mixtures in enzymatic catalysis: detection of conformation-dynamic processes].

An analysis was carried out of Gross-Butler type equations describing relationship between deuterium isotope effect in reactions with proton transfer and deuterium concentration in the medium. It has been shown that with all possible coefficient values of isotopic fractionation of enzyme functional group protons the shape of indicated relationships qualitatively differs from the experimentally observed one for myosin hydrolysis of ATP. This discrepancy as well as uniform nonlinear change of myosin denaturation temperature and of kinetic isotope effect in myosin hydrolysis of ATP on deuterium fraction in solution give evidence of D2O effect as a solvent and point to an essential role of conformational - dynamic processes in the course of enzymic catalysis with myosin.

Biophysical Phenomena↗
PubMed2006

Role of protein conformational dynamics and DNA integrity in relevance to neuronal cell death in neurodegeneration.

Apoptosis has been implicated in the pathogenesis of various neurodegenerative disorders, although the extent to which it is responsible for the neurodegeneration along with other kind of cell death events is not known. Eventhough much information is available today on the apoptotic cascades in general, the precise mechanism and the exact sequence of events leading to neuronal degeneration in Alzheimer's disease (AD) and other neurodegenerative disorders is not understood till now. Amyloid beta (Abeta) proteins are the hallmark toxic proteins known to cause the activation of apoptotic cascades via caspase dependent and caspase-independent pathways. Abeta can cause neuronal apoptosis through multiple mechanisms involving mitochondria and endoplasmic reticulum as the key organelles. In this review, we have discussed the role of apoptosis in neurodegeneration and provided new thoughts on the role of protein conformational dynamics and DNA integrity associated with neurodegenerative disorders. An insight on whether the apoptosis observed in the neurodegenerative disorders is of any functional advantage has been discussed.

Alzheimer Disease↗
PubMed1999

X-ray structure and conformational dynamics of the HIV-1 protease in complex with the inhibitor SDZ283-910: agreement of time-resolved spectroscopy and molecular dynamics simulations.

Based on the X-ray structure of the human immunodeficiency virus type-1 (HIV-1) protease in complex with the statine-derived inhibitor SDZ283-910, a 542 ps molecular dynamics trajectory was computed. For comparison with the 805 ps trajectory obtained for the uncomplexed enzyme, the theoretical fluorescence anisotropy decay of the unliganded protease and the inhibitor complex was calculated from the trajectories of the Trp6A/Trp6B and Trp42A/Trp42B transition dipole moments. This enabled us to directly compare the simulated data with the experimental picosecond time-resolved fluorescence data. Fitting both experimental and simulated data to the Kohlrausch-Williams-Watts (KWW) function exp(-t/tauk)beta revealed a very good agreement for the uncomplexed protease as well as for the SDZ283-910 complex. Binding of the inhibitor induced a faster decay of both the experimental and the computed protease fluorescence anisotropy decay. By this integrative approach, the atomic detail of inhibitor-induced changes in the conformational dynamics of the HIV-1 protease was experimentally verified and will be used for further inhibitor optimisation.

Anti-HIV Agents↗
PubMed1996

Mutation of Tyr235 in the NAD(H)-binding subunit of the proton-translocating nicotinamide nucleotide transhydrogenase of Rhodospirillum rubrum affects the conformational dynamics of a mobile loop and lowers the catalytic activity of the enzyme.

The Tyr residue in the mobile loop region of the soluble, domain I polypeptide (called Ths) of the proton-translocating transhydrogenase from Rhodospirillum rubrum has been substituted by Asn and by Phe. The recombinant proteins were expressed at high levels in Escherichia coli and purified to homogeneity. The two well defined resonances at 6.82 and 7.12ppm, observed in the one-dimensional proton NMR spectrum of wild-type protein, and previously attributed to the Tyr residue, were absent in both mutants. In the Tyr235 --> Phe mutant Ths, they were replaced by two new resonances at 7.26 and 7.33 ppm, characteristic of a Phe residue. In both mutants, narrow resonances attributable to Met residues (and in the Tyr235 --> Phe mutant, resonances attributable to Ala residues) were shifted relative to the wild type, but other features in the NMR spectra were unaffected. The conformational dynamics of the mobile loop closure in response to nucleotide binding by the protein were altered in the two mutants. The fluorescence emission from Trp72 was unaffected by both Tyr substitutions, and the fluorescence was still quenched by NADH. The mutant Ths proteins bound to chromatophore membranes depleted of their native Ths with undiminished affinity. In these reconstituted systems, the Km values for thio-NADP+ and NADH, during light-driven transhydrogenation, were similar to those of wild-type, but the kcat values were decreased about 2-fold. In reverse transhydrogenation, the Kmvalues for NADPH were slightly decreased in the mutants relative to wild-type, but those for acetyl pyridine adenine dinucleotide were increased about 10- and 13-fold, respectively, and the kcat values were decreased about 2- and 5-fold, respectively, in the Tyr235 --> Phe and Tyr235 --> Asn mutants. It is concluded that Tyr235 may contribute to the process of nucleotide binding and that substitution of this residue prevents proper functioning of the mobile loop in catalysis.

Asparagine↗
PubMed1985

Accessibility of sulfhydryl residues induced by cytochalasin B binding and conformational dynamics in the human erythrocyte glucose transporter.

Studies with intact cells have implicated essential sulfhydryl groups in the carrier-mediated glucose transport of human erythrocytes. In an attempt to identify and characterize such essential sulfhydryl residues we have studied the interaction of p-chloromercuribenzoate (PCMB) with a purified glucose transporter preparation (band 4.5) from human erythrocytes, in the presence and absence of its ligands, and the effects of this interaction on the binding of cytochalasin B (CB) to the transporter. At least 3 mol of PCMB reacted per mol of this preparation. A portion of the reaction was significantly enhanced in the presence of cytochalasin B. This enhancement was a saturable function of CB concentration, and was half-maximal at a CB concentration equal to the dissociation constant for the CB binding to the preparation. This CB-sensitive, PCMB reaction product comigrated with the band 4.5 on lithium dodecyl sulfate-polyacrylamide gel electrophoresis. An excess of D-glucose did not affect the PCMB reaction by itself in the absence of CB, but totally abolished the CB-induced enhancement of the PCMB reaction. PCMB inhibited the CB binding activity of the transporter preparation, and this inhibition was also enhanced in the presence of CB. These results suggest that CB binding perturbs the conformational dynamics of the glucose transporter resulting in an exposure of at least two sulfhydryl residues to PCMB reaction, and that some of these CB-sensitive sulfhydryl groups are essential for CB binding to the transporter.

Binding Sites↗
PubMed2002

Dynamic conformational model for the role of ITS2 in pre-rRNA processing in yeast.

Maturation of the large subunit rRNAs includes a series of cleavages that result in removal of the internal transcribed spacer (ITS2) that separates mature 5.8S and 25/28S rRNAs. Previous work demonstrated that formation of higher order secondary structure within the assembling pre-ribosomal particle is a prerequisite for accurate and efficient pre-rRNA processing. To date, it is not clear which specific sequences or secondary structures are required for processing. Two alternative secondary structure models exist for Saccharomyces cerevisiae ITS2. Chemical and enzymatic structure probing and phylogenetic comparisons resulted in one structure (Yeh & Lee, J Mol Biol, 1990, 211:699-712) referred to here as the "hairpin model." More recently, an alternate folded structure was proposed (Joseph et al., Nucleic Acids Res, 1999, 27:4533-4540), called here the "ring model." We have used a functional genetic assay to examine the potential significance of these predicted structures in processing. Our data indicate that elements of both structural models are important in efficient processing. Mutations that prevent formation of ring-specific structures completely blocked production of mature 25S rRNA, whereas those that primarily disrupt hairpin elements resulted in reduced levels of mature product. Based on these results, we propose a dynamic conformational model for the role of ITS2 in processing: Initial formation of the ring structure may be required for essential, early events in processing complex assembly and may be followed by an induced transition to the hairpin structure that facilitates subsequent processing events. In this model, yeast ITS2 elements may provide in cis certain of the functions proposed for vertebrate U8 snoRNA acting in trans.

Base Sequence↗
PubMed1999

Conformational dynamics and molecular recognition: backbone dynamics of the estrogen receptor DNA-binding domain.

We examined the internal mobility of the estrogen receptor DNA-binding domain (ER DBD) using NMR15N relaxation measurements and compared it to that of the glucocorticoid receptor DNA-binding domain (GR DBD). The studied protein fragments consist of residues Arg183-His267 of the human ER and residues Lys438-Gln520 of the rat GR. The15N longitudinal (R1) and transverse (R2) relaxation rates and steady state {1H}-15N nuclear Overhauser enhancements (NOEs) were measured at 30 degrees C at1H NMR frequencies of 500 and 600 MHz. The NOE versus sequence profile and calculated order parameters for ER DBD backbone motions indicate enhanced internal dynamics on pico- to nanosecond time-scales in two regions of the core DBD. These are the extended strand which links the DNA recognition helix to the second zinc domain and the larger loop region of the second zinc domain. The mobility of the corresponding regions of the GR DBD, in particular that of the second zinc domain, is more limited. In addition, we find large differences between the ER and GR DBDs in the extent of conformational exchange mobility on micro- to millisecond time-scales. Based on measurements of R2as a function of the15N refocusing (CPMG) delay and quantitative (Lipari-Szabo-type) analysis, we conclude that conformational exchange occurs in the loop of the first zinc domain and throughout most of the second zinc domain of the ER DBD. The conformational exchange dynamics in GR DBD is less extensive and localized to two sites in the second zinc domain. The different dynamical features seen in the two proteins is consistent with previous studies of the free state structures in which the second zinc domain in the ER DBD was concluded to be disordered whereas the corresponding region of the GR DBD adopts a stable fold. Moreover, the regions of the ER DBD that undergo conformational dynamics on the micro- to millisecond time-scales in the free state are involved in intermolecular protein-DNA and protein-protein interactions in the dimeric bound state. Based on the present data and the previously published dynamical and DNA binding properties of a GR DBD triple mutant which recognize an ER binding site on DNA, we argue that the free state dynamical properties of the nuclear receptor DBDs is an important element in molecular recognition upon DNA binding.

Amino Acid Sequence↗
PubMed2002

Macromolecular chirality induction on optically inactive poly(4-carboxyphenyl isocyanide) with chiral amines: a dynamic conformational transition of poly(phenyl isocyanide) derivatives.

Optically active polyisocyanides (poly(iminomethylenes)) have been prepared with much interest in developing new functional materials. Polyisocyanides have been considered to have a stable 4(1) helical conformation even in solution when they have a bulky side group. However, the conformational characteristics of poly(phenyl isocyanide) (PPI) derivatives are still under debate. We now report that an optically inactive PPI derivative, poly(4-carboxyphenyl isocyanide) (poly-1), shows optical activity in the polymer backbone induced by external, chiral stimuli through acid-base interactions under thermodynamic control and exhibits induced circular dichroism (ICD) in the UV-visible region in DMSO. The ICD intensities of the poly-1-chiral amine complexes in DMSO gradually increased with time, and, in one case, the value reached 3 times that of the original value after 2 months at 30 degrees C. The conformational changes also occurred very slowly for poly-1 alone and its ethyl ester with time on the basis of (1)H NMR spectroscopic analysis. These results indicate that PPIs bearing a less bulky substituent may not have a 4(1) helical conformation but have a different type of prochiral conformation, for instance, an s-trans (zigzag) structure which may transform to a dynamic, one-handed helical conformation when the PPIs have a functional group capable of interacting with chiral compounds. The mechanism of helicity induction on poly-1 through a dynamic conformational transition is discussed on the basis of the above results together with molecular dynamic simulation results for PPI.

Journal Article↗
PubMed2000

Conformational dynamics of the beta2-microglobulin C terminal in the cell-membrane-anchored major histocompatibility complex type I.

We have recently described an anti-beta2-microglobulin (beta2-m) monoclonal antibody (mAb 14H3) capable of recognizing the epitope 92-99 of the protein in the monomeric native state as well as in the fibrillar polymeric state, but not in the major histocompatibility complex type I (MHCI) anchored to the cell membrane. In the present study, we investigated the molecular basis for the inaccessibility of the C-terminal end of beta2-m in the MHCI complex, and demonstrated that mAb 14H3 binds the soluble fraction of the MHCI complex with a Kd of 0.3 microM. An interaction between the complex and the membrane protects beta2-m from immunological recognition at the MHCI level. This protection from antibody recognition can be weakened by procedures such as heat shock or gamma irradiation that perturb the membrane structure and commit the cell to the apoptotic pathway. mAb 14H3 can recognize MHCI in a transient state that most likely precedes beta2-m shedding and may be proposed as a useful tool for dynamic analysis of MHCI conformational modifications.

Antibodies, Monoclonal↗
PubMed1995

A spectroscopic investigation of the conformational dynamics of insulin in solution.

A conformational change, termed the T --> R transition, which can be detected by visible, circular dichoric, and fluorescence spectroscopy, occurs in native insulin and tryptophan substituted insulin analogs ([TrpB25]-, [TrpB26]-, [GlyB24,TrpB25]-, and [GlyB24,TrpB26]insulin) upon binding specific alcohol ligands, including phenol and cyclohexanol. In these studies we have demonstrated that changes in the visible absorbance spectrum of an insulin6(Co2+)2 solution are not a definitive means of determining the occurrence of T --> R transitions in the presence of alcohol ligands. We also have presented evidence that fast protein liquid chromatography (FPLC) can be used to determine the aggregation state of insulin and that des-octapeptide(B23-30)insulin (DOI) forms Zn(2+)-coordinated hexamers that appear to be stabilized by the T --> R transformation. Using fluorescence spectroscopy, we have shown that in the presence of specific alcohol ligands the B-chain COOH-terminal residues, particularly position B25, of hexameric, as well as monomeric insulin undergo a conformational change which appears to be related to the T --> R transformation. Circular dichroic studies indicate that a conformation similar to the R-state of metal-coordinated hexameric insulin can be induced by binding cyclohexanol; however, this new conformational state (RI-state) exists independent of divalent metal ion coordination, and therefore of hexamer formation. We further show that monomeric insulin can be induced to assume the RI-state upon alcohol binding, therefore illustrating the first defined conformational change described for monomeric insulin. We suggest that this new conformation may be an intermediate state in the T --> R transformation in metal-coordinated hexameric insulin, such that T --> RI --> R. The model presented here of the structural adjustments undergone by insulin upon binding cyclohexanol provides further insight into the conformational flexibility of insulin in solution.

Circular Dichroism↗