Conformational Profile Research Articles

A Combined theoretical and experimental study of conformational and spectroscopic profile of 2-acetamido-5-aminopyridine

Present work aims at identifying the conformational and spectroscopic profile of 2-acetamido-5-aminopyridine compound by means of experimental and computational methods. To achieve this, three-dimensional potential energy scan (PES) was performed by varying the selected dihedral angles at B3LYP/6-31+G(d,p) level of theory and thus stable conformers of the title compound were determined. The most stable conformer was further optimized at higher level and vibrational wavenumbers were calculated. Experimentally, vibrational features of title compound were determined by FT-IR and FT-Raman spectroscopic methods in the solid phase while the electronic absorption spectrum was recorded in methanol solution. On the basis of these investigations, the conformational and spectroscopic attributes of 2-acetamido-5-aminopyridine were interpreted.

Synthesis, characterization and density functional theory study of low cost hydrazone sensitizers

The 2-{4-[2-benzylidenehydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 1), 2-{4-[2-(1-naphthylmethylene)hydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 2) and 2-{4-[2-(9-anthrylmethylene)- hydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 3) were synthesized by direct tricyanovinylation of hydrazones. The bathochromic shift in absorption spectra has been observed by increasing the solvent polarity. The FTIR spectra of these new dyes exhibited three important absorption bands. The first band centered near 3260 cm-1 in System 1 while 3208 cm-1 and 3211 cm-1 in System 2 and System 3 for the nNH absorption, respectively. The second band is a sharp absorption band in the region of 2212-2209 cm-1, which was attributed to the cyano group absorption. The third is an absorption band in the region of 1611-1603 cm-1 ascribed for the C=N. Density functional theory (DFT) calculation of relative energies, relative enthalpies and free energies shows that E isomers are the most stable except System 3 in which the most stable is Z isomers. The conformational energy profile shows two maxima near (-90 and 90o) while three local minima observed at (-180, 0 and 180) for N1-N2-C1-C2 torsional angle. The highest occupied molecular orbitals (HOMOs) are localized on the whole molecules while lowest unoccupied molecular orbitals (LUMOs) are distributed on the tricarbonitrile. KEY WORDS: Dye-sensitized solar cells, HOMO, LUMO, Absorption, FTIR spectra Bull. Chem. Soc. Ethiop. 2015, 29(1), 137-148DOI: http://dx.doi.org/10.4314/bcse.v29i1.13

Analysis of the conformational profiles of fenamates shows route towards novel, higher accuracy, force-fields for pharmaceuticals.

In traditional molecular mechanics force fields, intramolecular non-bonded interactions are modelled as intermolecular interactions, and the form of the torsion potential is based on the conformational profiles of small organic molecules. We investigate how a separate model for the intramolecular forces in pharmaceuticals could be more realistic by analysing the low barrier to rotation of the phenyl ring in the fenamates (substituted N-phenyl-aminobenzoic acids), that results in a wide range of observed angles in the numerous fenamate crystal structures. Although the conformational energy changes by significantly less than 10 kJ mol(-1) for a complete rotation of the phenyl ring for fenamic acid, the barrier is only small because of small correlated changes in the other bond and torsion angles. The maxima for conformations where the two aromatic rings approach coplanarity arise from steric repulsion, but the maxima when the two rings are approximately perpendicular arise from a combination of an electronic effect and intramolecular dispersion. Representing the ab initio conformational energy profiles as a cosine series alone is ineffective; however, combining a cos 2ξ term to represent the electronic barrier with an intramolecular atom-atom exp-6 term for all atom pairs separated by three or more bonds (1-4 interactions) provides a very effective representation. Thus we propose a new, physically motivated, generic analytical model of conformational energy, which could be combined with an intermolecular model to form more accurate force-fields for modelling the condensed phases of pharmaceutical-like organic molecules.

Insights into the interactions between enzyme and co-solvents: Stability and activity of stem bromelain

In present study, an attempt is made to elucidate the effects of various naturally occurring osmolytes and denaturants on BM at pH 7.0. The effects of the varying concentrations of glycerol, sorbitol, sucrose, trehalose, urea and guanidinium chloride (GdnHCl) on structure, stability and activity of BM are explored by fluorescence spectroscopy, circular dichroism (CD), UV–vis spectroscopy and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Our experimental observations reveal that glycerol and sorbitol are acting as stabilizers at all concentrations while sucrose and trehalose are found to be destabilizers at lower concentrations, however, acted as stabilizers at higher concentrations. On the other hand, urea and GdnHCl are denaturants except at lower concentrations. There is a direct relationship between activity and conformational stability as the activity data are found to be in accordance with conformational stability parameters (ΔGu, Tm, ΔCp) and BM profile on SDS-PAGE.

Vibrational circular dichroism and theoretical study of the conformational equilibrium in (-)-S-nicotine.

We report an extensive study of the molecular and electronic structure of (-)-S-nicotine, to deduce the phenomenon that controls its conformational equilibrium and to solve its solution-state conformer population. Density functional theory, ab initio, and molecular mechanics calculations were used together with vibrational circular dichroism (VCD) and Fourier transform infrared spectroscopies. Calculations and experiments in solution show that the structure and the conformational energy profile of (-)-S-nicotine are not strongly dependent on the medium, thus suggesting that the conformational equilibrium is dominated by hyperconjugative interactions rather than repulsive electronic effects. The analysis of the first recorded VCD spectra of (-)-S-nicotine confirmed the presence of two main conformers at room temperature. Our results provide further evidence of the hypersensitivity of vibrational optical activity spectroscopies to the three-dimensional structure of chiral samples and prove their suitability for the elucidation of solution-state conformer distribution.

Abstract 4757: A novel class of selective estrogen receptors degraders regresses tumors in pre-clinical models of endocrine-resistant breast cancer

Abstract 80% of all breast cancers express the estrogen receptor alpha (ERα) and thus are treated with anti-hormonal therapies that directly block ER function (e.g.Tamoxifen) or hormone synthesis (Aromatase Inhibitors). While these therapies are initially effective, acquired resistance invariably emerges and disease progression ensues. Importantly, the majority of these tumors continue to depend on ERα for growth and survival via both ligand-dependent and ligand-independent pathways. The emerging evidence that ERα can be activated in the absence of estrogens via point mutations in ERα or cellular signaling pathways supports the development of agents that are not only competitive ERα antagonists but also reduce steady state levels of the receptor and thus limit both ligand dependent and independent signaling. We have identified two novel series of non-steroidal ERα antagonists, series I exemplified by ARN-810, now in clinical trials for treatment of endocrine resistant breast cancer, and series II, both of which induce degradation of ERα at picomolar concentrations resulting in significant reduction in steady state ERα protein levels in breast cancer cell lines. Using peptide-based conformational profiling, we show that both series induce ERα conformations that are distinct from both fulvestrant and tamoxifen indicating novel mechanism of action. In vitro, both ligand series are active on wild-type and the constitutively active ERα mutants found in endocrine resistant breast cancer patients. Importantly, these compounds yield tumor regression in both tamoxifen-sensitive and -resistant models of breast cancer in vivo. Based on their unique in vitro profile, and good pharmacokinetics following oral dosing, these compounds represent a novel class of Selective Estrogen Receptor Degraders (SERDs) that hold promise as a next generation therapy for the treatment of ER+ breast cancer as monotherapy, as well as in combination with agents that target other pathways involved in both intrinsic and acquired endocrine resistance. Citation Format: James D. Joseph, Beatrice Darimont, Steven Govek, Dan Brigham, Jing Qian, John Sensintaffar, Gang Shao, Anna Aparicio, Mehmet Kahraman, Andiliy Lai, Kyoung-Jin Lee, Nhin Lu, Johnny Nagasawa, Michael Moon, Peter Rix, Nick Smith, Jeff Hager. A novel class of selective estrogen receptors degraders regresses tumors in pre-clinical models of endocrine-resistant breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4757. doi:10.1158/1538-7445.AM2014-4757

Antiviral atropisomers: conformational energy surfaces by NMR for host-directed myxovirus blockers.

Biologically active organic molecules characterized by a high single bond torsional barrier generate isolable isomers (atropisomers) and offer a unique stereochemical component to the design of selective therapeutic agents. The present work presents a nanomolar active inhibitor of myxoviruses, which most likely acts by blocking one or more cellular host proteins but also, serendipitously, exhibits axial chirality with an energy barrier of ΔG((++)) ≥30 kcal/mol. The latter has been probed by variable temperature NMR and microwave irradiation and by high level DFT transition state analysis and force field calculations. Full conformational profiles of the corresponding (aR,S) and (aS,S) atropisomers at ambient temperature were derived by conformer deconvolution with NAMFIS (NMR Analysis by Molecular Flexibility In Solution) methodology to generate seven and eight individual conformations, each assigned a % population. An accurate evaluation of a key torsion angle at the center of the molecules associated with a (3)JC-S-C-H coupling constant was obtained by mapping the S-C bond rotation with the MPW1PW91/6-31G-d,p DFT method followed by fitting the resulting dihedral angles and J-values to a Karplus expression. Accordingly, we have developed a complete conformational profile of diastereomeric atropisomers consistent with both high and low rotational barriers. We expect this assessment to assist the rationalization of the selectivity of the two (aR,S) and (aS,S) forms against host proteins, while offering insights into their divergent toxicity behavior.

NMR characterization and conformational analysis of a potent papain-family cathepsin L-like cysteine protease inhibitor with different behaviour in polar and apolar media

We recently reported the synthesis, of a potent papain-family cathepsin L-like cysteine protease inhibitor, as new lead compound for the development of new drugs that can be used as antiprotozoal agents. The investigation of its conformational profile is crucial for the in-depth understanding of its biological behaviour. Our careful NMR analysis has been based on the complete and total assignment of 1H, 13C, 15N and 19F signals of the molecule in both CDCl3 and CD3OH, which could reproduce in some way a scenario of polar and not polar phases into the biological environment. In this way it has been unveiled a different behaviour of the molecule in polar and apolar media. In CDCl3 it is possible to define stable conformational arrangements on the basis of the detected through space contacts, whereas, in CD3OH a greater conformational freedom is envisaged: (a) by the overlap of any of the CH2 diastereotopic resonances (unable to distinguish asymmetric molecular sides because of the free rotation about the single bonded chains), (b) by the less definite measured vicinities not consistent with just one conformation and (c) by the evident loss or switching of key intramolecular hydrogen interactions.

The quest for a simple bioactive analog of paclitaxel as a potential anticancer agent.

ConspectusPaclitaxel (PTX), introduced into the clinic in 1991, has revealed itself as an effective antimicrotubule drug for treatment of a range of otherwise intractable cancers. Along with docetaxel (DTX) and in combination with other agents such as cisplatin, it has proven to be a first-line therapy. Unfortunately, PTX and DTX carry severe liabilities such as debilitating side effects, rapid onset of resistance, and rather complex molecular structures offering substantial challenges to ease of synthetic manipulation. Consequently, the past 15 years has witnessed many efforts to synthesize and test highly modified analogs based on intuitive structural similarity relationships with the PTX molecular skeleton, as well as efforts to mimic the conformational profile of the ligand observed in the macromolecular tubulin–PTX complex.Highly successful improvements in potency, up to 50-fold increases in IC50, have been achieved by constructing bridges between distal centers in PTX that imitate the conformer of the electron crystallographic binding pose. Much less successful have been numerous attempts to truncate PTX by replacing the baccatin core with simpler moieties to achieve PTX-like potencies and applying a wide range of flexible synthesis-based chemistries. Reported efforts, characterized by a fascinating array of baccatin substitutes, have failed to surpass the bioactivities of PTX in both microtubule disassembly assays and cytotoxicity measurements against a range of cell types. Most of the structures retain the main elements of the PTX C13 side chain, while seeking a smaller rigid bicycle as a baccatin replacement adorned with substituents to mimic the C2 benzoyl moiety and the oxetane ring.We surmise that past studies have been handicapped by solubility and membrane permeability issues, but primarily by the existence of an expansive taxane binding pocket and the discrepancy in molecular size between PTX and the pruned analogs. A number of these molecules offer molecular volumes 50–60% that of PTX, fewer contacts with the tubulin protein, severe mismatches with the PTX pharmacophore, lessened capacity to dispel binding site waters contributing to ΔGbind, and unanticipated binding poses. The latter is a critical drawback if molecular designs of simpler PTX structures are based on a perceived or known PTX binding conformation. We conclude that design and synthesis of a highly cytotoxic tubulin-assembly agent based on the paclitaxel pharmacophore remains an unsolved challenge, but one that can be overcome by focus on the architecture of the taxane binding site independent of the effective, but not unique, hand-in-glove match represented by the PTX–tubulin complex.

Physical Stability Comparisons of IgG1-Fc Variants: Effects of N-Glycosylation Site Occupancy and Asp/Gln Residues at Site Asn 297

The structural integrity and conformational stability of various IgG1-Fc proteins produced from the yeast Pichia pastoris with different glycosylation site occupancy (di-, mono-, and nonglycosylated) were determined. In addition, the physical stability profiles of three different forms of nonglycosylated Fc molecules (varying amino-acid residues at site 297 in the CH 2 domain due to the point mutations and enzymatic digestion of the Fc glycoforms) were also examined. The physical stability of these IgG1-Fc glycoproteins was examined as a function of pH and temperature by high-throughput biophysical analysis using multiple techniques combined with data visualization tools (three index empirical phase diagrams and radar charts). Across the pH range of 4.0-6.0, the di- and monoglycosylated forms of the IgG1-Fc showed the highest and lowest levels of physical stability, respectively, with the nonglycosylated forms showing intermediate stability depending on solution pH. In the aglycosylated Fc proteins, the introduction of Asp (D) residues at site 297 (QQ vs. DN vs. DD forms) resulted in more subtle changes in structural integrity and physical stability depending on solution pH. The utility of evaluating the conformational stability profile differences between the various IgG1-Fc glycoproteins is discussed in the context of analytical comparability studies.

A Compact Multi-Frequency, High Power Radiating System Combining Dual-Band, Electrically Small Magnetic EZ Antennas and Multi-Frequency Standing Wave Oscillator Sources

High power microwave (HPM) sources are typically bulky and massive in order to be able to radiate the extremely high source powers with a good impedance match and low losses. For this reason, it is sometimes difficult to incorporate an HPM antenna onto a desired platform when the available space is small. In previous work, we have adapted an electrically small EZ antenna to operate with a mesoband, quarter-wave oscillator source. The EZ antenna operates over a ground plane, but is conformal and low profile in that the electrical size is on the order of $\lambda /12$ , making it attractive for applications where there is sufficient internal space to place a full source, but only limited space outside the platform for the radiating subsystem. Here we extend the capabilities of the oscillator/EZ antenna combination by introducing a dual band design for the antenna and altering the oscillator to produce multiple resonant frequencies. Designs are shown here that operate in the UHF (500–800 MHz) and L-band (1.5–1.8 GHz), but the operation frequencies are essentially arbitrary. This paper shows modeling results that predict high antenna efficiency with electrical sizes of $ka at $f = 500~{\rm MHz}$ .

Describing the Conformational Landscape of Small Organic Molecules through Gaussian Mixtures in Dihedral Space.

Due to the well-known structure-function paradigm, conformational equilibrium plays a major role in molecular recognition. Therefore, a deep understanding of the conformational profile of small organic molecules is an essential prerequisite to modern computer-assisted drug design. However, a thorough analysis and a meaningful representation of the conformational landscape of drug-like molecules remains a challenge. The thermodynamic equilibrium of conformational states can be described in terms of probability density function (PDF) defined in the space of the relevant degrees of freedom of the system. In principle, this PDF could be estimated by traditional histogram methods, which are, however, hampered by several limitations when the variables forming the space are more than two or three. Here, we present an unsupervised parametric fitting procedure based on cluster analysis, aimed at estimating the PDF in the conformational space of small drug-like molecules with low sensitivity to data dimensionality. Indeed, data are represented in the dihedral space of the molecule and clustered using a simple adaptation of the standard k-means algorithm for periodic data. In the final step of the analysis, the PDF is derived as a linear combination of multivariate circular Gaussian distributions. We show that exploiting the analytic properties of Gaussian distributions, the proposed approach makes it possible to analyze the conformational ensemble in higher dimensional spaces with several advantages over the histogram-based methods. The posterior analysis of the PDF also helps identify a minimal subset of variables able to provide a meaningful representation of the conformational space. We tested our approach on alanine dipeptide, alanine tetrapeptide, and rilpivirine with satisfactory results compared to standard histogram-based methods and to those based on chemical intuition.

Chiral discrimination in dimers of diphosphines PH₂-PH₂ and PH₂-PHF.

A theoretical study of the conformational profile of two diphosphines, PH2-PH2 and PH2-PHF, is carried using second-order Møller-Plesset perturbation theory (MP2) computational methods. The chiral minima found are used to build homo- and heterochiral dimers. Six minima are found for the (PH2-PH2 )2 dimers and 27 for the (PH2-PHF)2 dimers. Pnicogen and hydrogen bonds, the non-covalent forces that stabilize the complexes, are characterized by Atoms in Molecules (AIM) and Natural Bond Orbital (NBO) methodologies. Those with several pnicogen bonds are more stable than those with hydrogen bonds. The chirodiastaltic energies amount to a total of 1.77 kJ mol(-1) for the Ra:Ra versus Ra:Sa (PH2-PH2 )2 dimers, 0.81 kJ mol(-1) for the RSa:RSa versus RSa:SRa (PH2-PHF)2 dimers, and 2.93 kJ mol(-1) for the RRa:RRa versus RRa:SSa (PH2-PHF)2 dimers. In the first and second cases, the heterochiral complex is favored whereas in the third case, the homochiral complex is favored.

The Role of the Conformational Profile of Polysaccharides on Skin Penetration: The Case of Hyaluronan and Its Sulfates

The literature data suggest the capacity of biomacromolecules to permeate the human skin, even though such a transdermal permeation appears to be governed by physicochemical parameters which are significantly different compared to those ruling the skin permeation of small molecules. On these grounds, the present study was undertaken to investigate the in vitro diffusion properties through the human epidermis of hyaluronic acid and their sulfates. Low- and medium-molecular-weight hyaluronic acids and the corresponding derivatives at two degrees of sulfation were then tested. In vitro studies evidenced that the sulfated polymers permeate better than the corresponding hyaluronic acid, despite their vastly greater polarity, while the observed permeation markedly decreases when increasing the polymer's molecular weight regardless of the sulfation degree. Using a fluorescent-labeled polysaccharide, it was also evidenced that hyaluronans have a great affinity for corneocytes and likely cross the stratum corneum mainly through a transcellular route. The molecular-dynamics study revealed how the observed permeations for the investigated polysaccharides can be rationalized by monitoring their conformational profiles, since the permeation was found to be directly related to their capacity to assume extended and flexible conformations.

Protein comparability assessments and potential applicability of high throughput biophysical methods and data visualization tools to compare physical stability profiles

In this review, some of the challenges and opportunities encountered during protein comparability assessments are summarized with an emphasis on developing new analytical approaches to better monitor higher-order protein structures. Several case studies are presented using high throughput biophysical methods to collect protein physical stability data as function of temperature, agitation, ionic strength and/or solution pH. These large data sets were then used to construct empirical phase diagrams (EPDs), radar charts, and comparative signature diagrams (CSDs) for data visualization and structural comparisons between the different proteins. Protein samples with different sizes, post-translational modifications, and inherent stability are presented: acidic fibroblast growth factor (FGF-1) mutants, different glycoforms of an IgG1 mAb prepared by deglycosylation, as well as comparisons of different formulations of an IgG1 mAb and granulocyte colony stimulating factor (GCSF). Using this approach, differences in structural integrity and conformational stability profiles were detected under stress conditions that could not be resolved by using the same techniques under ambient conditions (i.e., no stress). Thus, an evaluation of conformational stability differences may serve as an effective surrogate to monitor differences in higher-order structure between protein samples. These case studies are discussed in the context of potential utility in protein comparability studies.

A Simple Procedure for the Solution of Three-Dimensional Wheel/Rail Conformal Contact Problem

This paper describes a simple and efficient procedure for the treatment of conformal contact conditions with special emphasis on railroad wheel/rail contacts. The general three-dimensional nonconformal contact conditions are briefly reviewed. These nonconformal contact conditions, which are widely used in many applications because of their generality, allow for predicting online one point of contact, provided that the two surfaces in contact satisfy certain geometric requirements. These nonconformal contact conditions fail when the solution is not unique as the result of using conformal surface profiles or surface flatness, situations often encountered in many applications including railroad wheel/rail contacts. In these cases, the Jacobian matrix obtained from the differentiation of the nonconformal contact conditions with respect to the surface parameters suffer from singularity that causes interruption of the computer simulations. The singularities and the fundamental issues that arise in the case of conformal contact are discussed, and a simple and computationally efficient procedure for avoiding such singularities in general multibody systems (MBS) algorithms is proposed. In order to demonstrate the use of the proposed procedure, the wheel climb of a wheelset as the result of an external lateral force is considered as an example. In this example, the wheel and rail profiles lead to conformal contact scenarios that could not be simulated using the nonconformal contact conditions.

A study of the conformational profile and the vibrational spectra of the plant hormone indole-3-acetic acid

The structural stability of indole-3-acetic acid was investigated by DFT-B3LYP calculations with the 6-311G** basis set. From the calculations the gauche–gauche (gg) structure was predicted to be the second lowest energy minimum for the acid. It is energetically only 0.57 kcal/mol above the lowest conformer which is the trans–cis (tc) structure. A further stable conformer, however, highest in energy, is the trans–trans (tt) one, which is by 2.68 kcal/mol higher in energy than tc. The tc conformer upon full optimization turned a little bit away from real tc to a near tc (ntc) structure (defining torsional angles only changed by a few decigrades). However, the X-ray data indicate a structure in the solid, which is most similar to gg, stabilized by intermolecular eight ring hydrogen bonds. In the present DFT calculations such stabilizations cannot be accounted for, because the calculations treat only isolated molecules. To take such interactions into account at least dimers would have to be optimized. Therefore the vibrational frequencies of the gg conformer were computed at the B3LYP level of theory and tentative vibrational assignments were provided on the basis of normal coordinate analysis, normal mode calculations and experimental infrared and Raman data. However, some of the observed lines are obviously due to a small amount of the tc conformer present.

Research and design of thermal cloak in arbitary shape

On the basis of transformation thermodynamics, a thermal conductivity expression for cylindrical thermal cloak with arbitrary cross section is derived. Based on the expression, we design a thermal cloak with a non conformal section profile. Results of full wave simulation show that the cloak possesses heat protection function, since it is capable of guiding heat fluxes to travel around its inner domain, leaving the inner region untouched; meanwhile, the heat fluxes return to their original pathways, resulting in a perfect thermal invisible effect. Arbitrary shaped cylindrical thermal cloak with conformal or non-conformal cross section can be designed based on the derived thermal conductivity expression, and all of them have perfect thermal protection and invisibility functions. It is indicated that the derived conductivity expression is applicable to designing cylindrical thermal cloaks with an arbitrary cross section. The generality of this method has been confirmed, and it may have potential applications in the designing of thermal protection devices for computer chips and satellite, etc.

The structural properties of DNA regulate gene expression

Regulatory sequences such as promoters not only contain cis-regulatory elements as switches of transcription, but also exhibit particular topological features. In this paper, we introduce a systematic genome scale approach to characterize the roles of structural conformation and stability profile of promoter sequence in gene expression. The average free energy of promoter dinucleotides stacking nearest neighbors are subjected to scrutiny by statistical hidden Markov models to reveal the function of constrains and properties of promoter structure in transcription. When applied for a 1000 bp 5' upstream sequence of genes, the proposed model via assessing free energy profile identified co-expressed genes of Arabidopsis thaliana in response to the auxin hormone. The applied perspective dynamic network which mediates transcription regulation provides a great hindrance to conceive how DNA conformation interacts with cis-regulatory elements, chromatin structure and many other factors. This study indeed drew the complexity of the promoter's regulatory behavior from sequence over the former studies and evokes a new hypothesis to be validated experimentally.

Structure-functional prediction and analysis of cancer mutation effects in protein kinases.

A central goal of cancer research is to discover and characterize the functional effects of mutated genes that contribute to tumorigenesis. In this study, we provide a detailed structural classification and analysis of functional dynamics for members of protein kinase families that are known to harbor cancer mutations. We also present a systematic computational analysis that combines sequence and structure-based prediction models to characterize the effect of cancer mutations in protein kinases. We focus on the differential effects of activating point mutations that increase protein kinase activity and kinase-inactivating mutations that decrease activity. Mapping of cancer mutations onto the conformational mobility profiles of known crystal structures demonstrated that activating mutations could reduce a steric barrier for the movement from the basal “low” activity state to the “active” state. According to our analysis, the mechanism of activating mutations reflects a combined effect of partial destabilization of the kinase in its inactive state and a concomitant stabilization of its active-like form, which is likely to drive tumorigenesis at some level. Ultimately, the analysis of the evolutionary and structural features of the major cancer-causing mutational hotspot in kinases can also aid in the correlation of kinase mutation effects with clinical outcomes.