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Registro Completo |
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Biblioteca(s): |
Embrapa Caprinos e Ovinos. |
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Data corrente: |
26/06/2024 |
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Data da última atualização: |
26/06/2024 |
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Autoria: |
BOYE, J. J.; ISMAIL, A. A.; ALLI, I. |
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Afiliação: |
JOYCE I. BOYE; ASHRAF A. ISMAIL; INTEAZ ALLI. |
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Título: |
Effects of physicochemical factors on the secondary structure of beta-lactoglobulin. |
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Ano de publicação: |
1996 |
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Fonte/Imprenta: |
Journal of Dairy Research, v. 63, n. 1, p. 97-109, Feb. 1996. |
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DOI: |
10.1017/s0022029900031575. |
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Idioma: |
Inglês |
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Conteúdo: |
Abstract: Fourier transform infrared spectroscopy and differential scanning calorimetry were used as complementary techniques to study changes in the secondary structure of beta-lactoglobulin under various physicochemical conditions. The effects of pH (3-9), NaCl (0-2 M), and lactose, glucose and sucrose (100-500 g/l) in the temperature range 25-100 degrees C on the conformation sensitive amide I band in the i.r. spectrum of beta-lactoglobulin in D2O solution were examined. The 1692 cm-1 band in the amide I band profile had not been definitively assigned in previous studies of the i.r. spectrum of beta-lactoglobulin. The decrease in this band at ambient temperature with time or upon mild heating was attributed to slow H-D exchange, indicating that it was due to a structure buried deep within the protein. The disappearance of the 1692 cm-1 band on heating was accompanied by the appearance of two bands at 1684 and 1629 cm-1, assigned to beta-sheets. The 1692 cm-1 band was therefore attributed to a beta-type structure. beta-Lactoglobulin showed maximum thermal stability at pH 3 and was easily denatured at pH 9. On denaturation, the protein unfolded into more extensive random coil structures at pH 9 than at pH 3. After 10 h at pH 9 (25 degrees C), beta-lactoglobulin was partly denatured. Heating to 60-80 degrees C generally resulted in the loss of secondary structure. At all pH values studied, two new bands at 1618 and 1684 cm-1, characteristic of intermolecular beta-sheet structure and associated with aggregation, were observed after the initial denaturation. Differential scanning calorimetry studies indicated that the thermal stability of beta-lactoglobulin was enhanced in the presence of sugars. The Fourier transform i.r. results obtained provide evidence that sugars promoted the unfolding of beta-lactoglobulin via multiple transition pathways leading to a transition state resisting aggregation. MenosAbstract: Fourier transform infrared spectroscopy and differential scanning calorimetry were used as complementary techniques to study changes in the secondary structure of beta-lactoglobulin under various physicochemical conditions. The effects of pH (3-9), NaCl (0-2 M), and lactose, glucose and sucrose (100-500 g/l) in the temperature range 25-100 degrees C on the conformation sensitive amide I band in the i.r. spectrum of beta-lactoglobulin in D2O solution were examined. The 1692 cm-1 band in the amide I band profile had not been definitively assigned in previous studies of the i.r. spectrum of beta-lactoglobulin. The decrease in this band at ambient temperature with time or upon mild heating was attributed to slow H-D exchange, indicating that it was due to a structure buried deep within the protein. The disappearance of the 1692 cm-1 band on heating was accompanied by the appearance of two bands at 1684 and 1629 cm-1, assigned to beta-sheets. The 1692 cm-1 band was therefore attributed to a beta-type structure. beta-Lactoglobulin showed maximum thermal stability at pH 3 and was easily denatured at pH 9. On denaturation, the protein unfolded into more extensive random coil structures at pH 9 than at pH 3. After 10 h at pH 9 (25 degrees C), beta-lactoglobulin was partly denatured. Heating to 60-80 degrees C generally resulted in the loss of secondary structure. At all pH values studied, two new bands at 1618 and 1684 cm-1, characteristic of intermolecular beta-sheet struc... Mostrar Tudo |
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Palavras-Chave: |
Chemical phenomena; Chemistry physical; Hot Temperature; Hydrogen Ion Concentration. |
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Thesagro: |
Lactose. |
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Thesaurus Nal: |
Deuterium; Differential scanning calorimetry; Fourier transform infrared spectroscopy; Glucose; Hydrogen; Lactoglobulins; Pharmacology; Protein denaturation; Protein structure; Sodium chloride; Sucrose. |
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Categoria do assunto: |
L Ciência Animal e Produtos de Origem Animal |
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Marc: |
LEADER 02957naa a2200349 a 4500
001 2165128
005 2024-06-26
008 1996 bl uuuu u00u1 u #d
024 7 $a10.1017/s0022029900031575.$2DOI
100 1 $aBOYE, J. J.
245 $aEffects of physicochemical factors on the secondary structure of beta-lactoglobulin.$h[electronic resource]
260 $c1996
520 $aAbstract: Fourier transform infrared spectroscopy and differential scanning calorimetry were used as complementary techniques to study changes in the secondary structure of beta-lactoglobulin under various physicochemical conditions. The effects of pH (3-9), NaCl (0-2 M), and lactose, glucose and sucrose (100-500 g/l) in the temperature range 25-100 degrees C on the conformation sensitive amide I band in the i.r. spectrum of beta-lactoglobulin in D2O solution were examined. The 1692 cm-1 band in the amide I band profile had not been definitively assigned in previous studies of the i.r. spectrum of beta-lactoglobulin. The decrease in this band at ambient temperature with time or upon mild heating was attributed to slow H-D exchange, indicating that it was due to a structure buried deep within the protein. The disappearance of the 1692 cm-1 band on heating was accompanied by the appearance of two bands at 1684 and 1629 cm-1, assigned to beta-sheets. The 1692 cm-1 band was therefore attributed to a beta-type structure. beta-Lactoglobulin showed maximum thermal stability at pH 3 and was easily denatured at pH 9. On denaturation, the protein unfolded into more extensive random coil structures at pH 9 than at pH 3. After 10 h at pH 9 (25 degrees C), beta-lactoglobulin was partly denatured. Heating to 60-80 degrees C generally resulted in the loss of secondary structure. At all pH values studied, two new bands at 1618 and 1684 cm-1, characteristic of intermolecular beta-sheet structure and associated with aggregation, were observed after the initial denaturation. Differential scanning calorimetry studies indicated that the thermal stability of beta-lactoglobulin was enhanced in the presence of sugars. The Fourier transform i.r. results obtained provide evidence that sugars promoted the unfolding of beta-lactoglobulin via multiple transition pathways leading to a transition state resisting aggregation.
650 $aDeuterium
650 $aDifferential scanning calorimetry
650 $aFourier transform infrared spectroscopy
650 $aGlucose
650 $aHydrogen
650 $aLactoglobulins
650 $aPharmacology
650 $aProtein denaturation
650 $aProtein structure
650 $aSodium chloride
650 $aSucrose
650 $aLactose
653 $aChemical phenomena
653 $aChemistry physical
653 $aHot Temperature
653 $aHydrogen Ion Concentration
700 1 $aISMAIL, A. A.
700 1 $aALLI, I.
773 $tJournal of Dairy Research$gv. 63, n. 1, p. 97-109, Feb. 1996.
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Embrapa Caprinos e Ovinos (CNPC) |
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