A física no contexto da biologia molecular

Nas últimas décadas tem havido uma crescente abordagem física no estudo de moléculas e sistemas macromoleculares de interesse biológico. Essa abordagem inclui tanto aspectos experimentais quanto teóricos. de fato, há um vasto campo a ser explorado pela física nessa área. Discutimos neste texto as características gerais e formação básica do profissional interessado em ter como objeto o estudo de sistemas biomoleculares, tanto em nível de graduação como na pós-graduação. Nessa linha de pensamento, assuntos como a formação básica e os fundamentos biológicos e físicos são discutidos.

Prospecção de novos peptídeos com ação leishmanicida por dinâmica molecular

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudos computacionais de esfingomielinases D: docking, dinâmica molecular e métodos híbridos QM/MM

Pós-graduação em Biofísica Molecular - IBILCE

Estudos computacionais de esfingomielinases D: docking, dinâmica molecular e métodos híbridos QM/MM

Pós-graduação em Biofísica Molecular - IBILCE

Thermodynamic origin of cooperativity in actomyosin interactions: The coupling of short-range interactions with actin bending stiffness in an Ising-like model

We present Monte Carlo simulations for a molecular motor system found in virtually all eukaryotic cells, the acto-myosin motor system, composed of a group of organic macromolecules. Cell motors were mapped to an Ising-like model, where the interaction field is transmitted through a tropomyosin polymer chain. The presence of Ca(2+) induces tropomyosin to block or unblock binding sites of the myosin motor leading to its activation or deactivation. We used the Metropolis algorithm to find the transient and the equilibrium states of the acto-myosin system composed of solvent, actin, tropomyosin, troponin, Ca(2+), and myosin-S1 at a given temperature, including the spatial configuration of tropomyosin on the actin filament surface. Our model describes the short- and long-range cooperativity during actin-myosin binding which emerges from the bending stiffness of the tropomyosin complex. We found all transition rates between the states only using the interaction energy of the constituents. The agreement between our model and experimental data also supports the recent theory of flexible tropomyosin.

Two-way MANCOVA: an application to public health

The aim of this work is to use the MANCOVA model to study the influence of the phenotype of an enzyme - Acid phosphatase - and a genetic factor - Haptoglobin genotype - on two dependent variables - Activity of Acid Phosphatase (ACP1) and the Body Mass Index (BMI). Therefore it's used a general linear model, namely a multivariate analysis of covariance (Two-way MANCOVA). The covariate is the age of the subject. This covariate works as control variable for the independent factors, serving to reduce the error term in the model. The main results showed that only the ACP1 phenotype has a significant effect on the activity of ACP1 and the covariate has a significant effect in both dependent variables. The univariate analysis showed that ACP1 phenotype accounts for about 12.5% of the variability in the activity of ACP1. In respect to this covariate it can be seen that accounts for about 4.6% of the variability in the activity of ACP1 and 37.3% in the BMI.

Complexation to macromolecules with a large number of sites

This paper presents an approach based on the saddle-point approximation to study the equilibrium interactions between small molecules and macromolecules with a large number of sites. For this case, the application of the Darwin–Fowler method results in very simple expressions for the stoichiometric equilibrium constants and their corresponding free energies in terms of integrals of the binding curve plus a correction term which depends on the first derivatives of the binding curve in the points corresponding to an integer value of the mean occupation number. These expressions are simplified when the number of sites tends to infinity, providing an interpretation of the binding curve in terms of the stoichiometric stability constants. The formalism presented is applied to some simple complexation models, obtaining good values for the free energies involved. When heterogeneous complexation is assumed, simple expressions are obtained to relate the macroscopic description of the binding, given by the stoichiomeric constants, with the microscopic description in terms of the intrinsic stability constants or the affinity spectrum. © 1999 American Institute of Physics.

Polymer induced condensation of DNA supercoils

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

On the interaction of small molecules with hemoproteins: Sperm whale myoglobin

The spin label TEMPO does not show a binding to myoglobin molecule in solution. This is probably due to the fact that this protein does not have a hydrophobic pocket large enough to accommodate the TEMPO molecule. In the crystal the spin label is bound and two kinds of spectra are observed: one isotropic and the other anisotropic. The anisotropic site is probably an intermolecular one. The correlation time for the label in the crystal is very sensitive to temperature showing a transition near 30 °C. This change can be explained as a result of the conformational change observed for myoglobin near this temperature: the motion of the spin label becomes more restricted below this temperature. Change in hydration is the probable cause of this structural change. The changes in the EPR spectra of the anisotropic label suggest that it is bound near the first layers of protein in the crystal. © 1985 Societá Italiana di Fisica.

Caracterização biofísica e estrutural da metaloproteinase não-hemorrágica do veneno de Bothrops moojeni e da endo-β-glicanase do Bacillus subtilis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo do coeficiente de difusão no enovelamento de proteínas na rede

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Análise vibracional do α-tocoferol

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudos dos efeitos de carga e da hidrofobicidade na interação de peptídeos antimicrobianos e membranas modelo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Glutationa como agente alostérico em hemoglobina bovina, humana e de e matrinxã

Pós-graduação em Biologia Animal - IBILCE

O papel das argininas α-92 e α-141 na regulação da função de hemoglobinas por íons cloreto

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)