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Master's Dissertation
DOI
10.11606/D.54.1989.tde-01092014-145731
Document
Author
Full name
Marinonio Lopes Cornelio
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1989
Supervisor
Committee
Sanches, Rosemary (President)
Onuchic, Jose Nelson
Vargas, Helion
Title in Portuguese
Estudo por espectroscopia fotoacústica dos efeitos da hidratação em hemoproteínas
Keywords in Portuguese
Espectroscopia fotoacústica
Hidratação de hemoproteinas
Abstract in Portuguese
No presente trabalho, realizado com hemoproteínas na forma de pó, o efeito da hidratação foi observado através de espectroscopia fotoacústica. Amostras de carboxi-hemoglobina e carboxi-mioglobina mantidas em diferentes ambientes de umidade relativa (UR), mostraram variações em seus espectros na região da banda de Soret. Para amostras mantidas em baixa hidratação característico do derivado carboxi, em alta hidratação (acima de aproximadamente 90% UR) o espectro era característico do derivado carboxi e na região intermediária o espectro era de uma mistura dos dois derivados. Essa mudança de ligante observada em alta hidratação pode ser explicada supondo que a proteína tem flexibilidade e atinge um estado conformacional que possibilita a entrada e saída do ligante. Em baixa hidratação a estrutura da proteína é rígida e tal que o acesso ao grupo heme está fechado, impossibilitando a troca do ligante. Essa explicação é coerente com vários resultados experimentais que indicam a existência de duas estruturas para essas hemoproteínas em solução
Title in English
Hydration effect of hemoproteins studied by photoacoustic spectroscopy
Keywords in English
Hydration of hemoproteins
Photoacoustic spectroscopy
Abstract in English
At the present work accomplished with powder of hemoproteins, the hydration effect was observed through photoacoustic spectroscopy. Samples of caroxyhemoglobin and carboxymyglobin kept at different relative humidity (RH) environments, showed variations in their spectra in the Soret bad region. For the samples which were kept at low hydration (Bellow about 33% RH) the spectrum was characteristic of carboxy derivative, whereas at high hydration (above about 93% RH) the spectrum was characteristic of oxy derivative, and in the the intermediate region the spectrum was a mixture of both derivatives. This ligand change observed at high hydration, may be explained assuming that the protein has flexibility, and reach a conformational state which enables the ligand to GO in and out. At low hydrations the protein structure is rigid and such that the access to the heme group is closed becoming impossible the ligand change. This explanation agrees with several experimental results that point to the existence of two structures to these hemoproteins in solution
 
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Publishing Date
2014-09-02
 
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