A differential scanning calorimetry analysis of the age-related changes in the thermal stability of rat skin collagen

Hidrólise seletiva de carboxiamidas de resíduos de asparagina e glutamina em colágeno: preparação e caracterização de matrizes aniônicas para uso como biomateriais

“…A banda em 1235 cm -1 corresponde às vibrações da amida III (estiramento C-N e vibração N-H), que são sensíveis à alterações na estrutura secundária do tropocolágeno (hélice tripla), enquanto a banda em 1450 cm -1 corresponde às vibrações dos anéis pirrolidínico de prolina e hidroxiprolina, que diferentemente da banda em 1235 cm -1 , tem sua intensidade independente das variações estruturais da matriz do colágeno 22 . A integridade da estrutura secundária hélice tripla no colágeno foi confirmada também em todos os materiais, pela presença de transição térmica 23 determinada como Ts ou Td (Tabela 1) e, para o C e cerca de 14 a 16 o C maiores quando comparadas com as transições observadas para os mesmos materiais equilibrados a pH 3,5 (Tabela 1). Estas diferenças para materiais submetidos à hidrólise foram de apenas 6 a 7 o C. Para o caso dos materiais de colágeno nativo, as diferenças observadas nas estabilidades térmicas determinadas a pH 3,5 e 7,4, estão de acordo com a desorganização do arranjo macromolecular (microfibrilas) que caracterizam o colágeno nativo a pH 7,4 (Figura 4a), mas que em pHs inferiores a 4,25 se transforma no colágeno "swollen" 22 (Figura 4b), uma estrutura amorfa, sem qualquer padrão de arranjo macromolecular.…”

Thermal stability of collagen in naturally ageing and in vitro glycated rabbit tissues

“…The main macromolecule of extracellular matrix in these tissues is type I collagen, even though the other components and the structure of the matrix are different [35][36][37]. Collagen in tissues was frequently characterized in the terms of thermal denaturation parameters [24][25][26][27][28][29][30][31][32], and in particular, differences in temperature of denaturation were used as an Table 2 Parameters of thermal denaturation of cornea from young adult (Y-) and ageing (A-) rabbits incubated in ribose solution (-R) and in buffer (-B) Mean values (standard deviation) are listed; n = 6 in each group p values for significance of differences between -B and -R samples calculated from paired t test Thermal stability of collagen in naturally ageing and in vitro glycated rabbit tissues 1907 indicator of differences in collagen crosslinking on the basis of numerous reports from previous experiments [17,18,20,21,25,27,38]. The temperature of denaturation in corneal samples was not different between young mature (Y-C) and ageing (A-C) groups (Table 1).…”

“…Conditions in which collagen molecules denature were frequently examined by using differential scanning calorimetry (DSC). Changes in the temperature and enthalpy of denaturation, as well as shape of the curve, were shown to be associated with differences in the post-translational modifications of collagen, and especially, the temperature was proved to be sensitive to the presence of crosslinks [17][18][19][20][21]. Parameters of thermal denaturation are also very sensitive to hydration of collagen fibres [22][23][24].…”

“…Parameters of thermal denaturation are also very sensitive to hydration of collagen fibres [22][23][24]. The thermal studies of collagens were conducted using model collagen-like peptides [14], collagens extracted from tissues [17,18,22,23,25] and on tissue collagens in situ [24][25][26][27][28][29][30][31][32]. Tissues from musculoskeletal system were the most frequently examined [24-26, 28, 29, 32], and thermal parameters of collagen denaturation were shown to be related to different types of the tissues disorders.…”

On Thermodynamics, Entropy and Evolution of Biological Systems: What Is Life from a Physical Chemist's Viewpoint

“…For example, the influence of the age of rat skin collagen on the temperature and heat of denaturation was studied by differential scanning calorimetry (DSC) [19].…”