| Summary: | Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-01-12T11:50:46Z
No. of bitstreams: 1
2016 - Otavio Augusto Chaves.pdf: 6300833 bytes, checksum: 156947ce06fa4e3b0674f5eaeaa4ef06 (MD5) === Made available in DSpace on 2017-01-12T11:50:46Z (GMT). No. of bitstreams: 1
2016 - Otavio Augusto Chaves.pdf: 6300833 bytes, checksum: 156947ce06fa4e3b0674f5eaeaa4ef06 (MD5)
Previous issue date: 2016-07-19 === Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq === The interactions between human serum albumin (HSA) with 18-PF, BZL, MTZ and
MZ and between bovine serum albumin (BSA) with t-DCTN, PF, LF-B, PIA and ?-lap were
studied by spectroscopic techniques (molecular absorption in the UV-Vis region, circular
dichroism, emission fluorescence in the steady state and temporal resolution) under
physiological conditions. Theoretical calculations by molecular docking were performed to
complement the experimental data and thus offer accurate to the results. The results obtained
for the fluorescence quenching rate constant (kq) is greater than the diffusion rate constant in
water (kdiff ? 5,00x109 L/mol), indicating that there is formation of complex between albumin
and biologically active molecules in the ground state (for the sample PIA we confirmed this
data with time resolved fluorescence experiments). For t-DCTN and LF-B beyond the static
mechanism it was observed the presence of dynamic fluorescence quenching mechanism.
Finally, for PF and PIA F?rster theory shows that the energy transfer between the fluorophore
and the quenchers can occurs with high probability. The thermodynamic values for Gibbs?
free energy are in accordance with the spontaneity of the association, for all the samples.
Thermodynamic parameters ?H? and ?S? provided evidence of the main intermolecular
interactions in the association. The samples 18-FP, t-DCTN, LF-B, PIA, ?-lap, BZL and MTZ
interact with albumin by hydrogen bonding and hydrophobic interactions. On the other hand,
PF and MZ interact by hydrogen bonding and electrostatic forces. The number of binding
sites shows that there is only one main cavity of the protein to the interaction. For 18-PF, PF
and LF-B the binding is weak, for t-DCTN the binding is moderate and for PIA, ?-lap, BZL,
MTZ and MZ the binding is strong. Circular dichroism results show that upon binding of
samples with the albumin there are no significant perturbations on the secondary structure of
the protein. Theoretical calculations by molecular docking are in full agreement with the
spectroscopic results === As intera??es entre albumina s?rica humana (ASH) com 18-FP, BZL, MTZ e MZ e
entre albumina s?rica bovina (ASB) com t-DCTN, PF, LF-B, PIA e ?-lap foram estudadas por
t?cnicas espectrosc?picas (absor??o molecular no UV-Vis, dicro?smo circular, emiss?o de
fluoresc?ncia no estado estacion?rio e com resolu??o temporal) sobre condi??es fisiol?gicas.
C?lculos te?ricos por ancoramento molecular (do ingl?s molecular docking) foram executados
para complementa??o dos dados experimentais e dessa forma obter resultados mais precisos.
Os resultados obtidos para as constantes de velocidade de supress?o de fluoresc?ncia das
albuminas (kq) s?o maiores do que a velocidade de difus?o em ?gua (kdiff ? 5,00x109 L/mols),
indicando que h? forma??o de um complexo no estado fundamental entre as albuminas com
as mol?culas biologicamente ativas (para amostra PIA tal dado foi confirmado com a
fluoresc?ncia resolvida no tempo). Para as amostras t-DCTN e LF-B al?m do mecanismo
est?tico foi observado ? presen?a do mecanismo din?mico e j? para as amostras PF e PIA o
c?lculo de F?rster mostra alta probabilidade de ocorr?ncia de transfer?ncia de energia entre o
fluor?foro e os supressores. Os valores termodin?micos de energia livre de Gibbs, calculados
para todas as amostras est?o de acordo com a espontaneidade da associa??o. Par?metros
termodin?micos de ?H? e ?S? forneceram ind?cios das principais intera??es intermoleculares
na associa??o. As amostras 18-FP, t-DCTN, LF-B, PIA, ?-lap, BZL e MTZ associam com a
albumina via liga??o de hidrog?nio e intera??es hidrof?bicas e j? PF e MZ por liga??o de
hidrog?nio e intera??es eletrost?ticas. O n?mero de s?tios de liga??o para todas as amostras
indicam que h? apenas uma principal cavidade da prote?na para a associa??o das mol?culas
estudadas, sendo que essa associa??o ? moderada para 18-FP, PF e LF-B, fraca para t-DCTN
e forte para PIA, ?-lap, BZL, MTZ e MZ. Estudos de dicro?smo circular demonstram que n?o
h? perturba??es significativas na estrutura secund?ria da albumina com a associa??o. C?lculos
te?ricos via ancoramento molecular est?o em total acordo com os resultados espectrosc?picos
|
|---|
