Temperature induced denaturation of collagen in acidic solution

Abstract

The denaturation of collagen solution in acetic acid has been investigated by using ultra-sensitive differential scanning calorimetry (US-DSC), circular dichroism (CD), and laser light scattering (LLS). US-DSC measurements reveal that the collagen exhibits a bimodal transition, i.e., there exists a shoulder transition before the major transition. Such a shoulder transition can recover from a cooling when the collagen is heated to a temperature below 35 degrees C. However, when the heating temperature is above 37 degrees C, both the shoulder and major transitions are irreversible. CD measurements demonstrate the content of triple helix slowly decreases with temperature at a temperature below 35 degrees C, but it drastically decreases at a higher temperature. Our experiments suggest that the shoulder transition and major transition arise from the defibrillation and denaturation of collagen, respectively. LLS measurements show the average hydrodynamic radius R(h), radius of gyration R(g)of the collagen gradually decrease before a sharp decrease at a higher temperature. Meanwhile, the ratio R(g)/R(h) gradually increases at a temperature below approximately 34 degrees C and drastically increases in the range 34-40 degrees C, further indicating the defibrillation of collagen before the denaturation.

Three intrinsically unstructured mussel adhesive proteins, mfp‐1, mfp‐2, and mfp‐3: Analysis by circular dichroism

“…In the context of the measured hydrodynamic radius of 11 nm for mfp-1, the CD data are consistent with a structure in which short, localized regions of order (PPII) are separated by unstructured sequences, and thus resulting in a flexible molecular ''necklace'' with small structured domains. In contrast, uninterrupted PPII structures such as tropocollagen and plant cell-wall proteins have much larger hydrodynamic radii, namely 200 nm 34 and 89 nm, 35 respectively.…”

Collagen Cryogel Cross‐Linked by Dialdehyde Starch

“…[18] In brief, collagen used in this study was isolated form adult bovine Achilles tendon using acetic acid. After dry milling and degreasing, the collagen was extracted with 0.5 M acetic acid at 4 8C for 2 days under stirring and salted out with 0.75 M NaCl.…”

“…It is known that the denaturation of collagen or its triple helix structure destruction results in a red shift of the negative band and disappearance of the positive band. [18,33,34] Here, the absent negative bands are due to a higher protein concentration since the absorbance of such a negative band was beyond the limit of detection in collagen solution at the same concentration (3.0 mg Á mL À1 ). Nevertheless, that the positive band at %227 nm for the cryogels is attributed to a collagen fold-on domain [35] is nearly the same as that for pure collagen, clearly indicating that the triple helical conformation in the cryogels does not change by the crosslinking.…”

Soluble collagen dissolution and assembling in pressurized carbon dioxide water solutions

“…From these results we can assert that the combination of both high pressure (0.3-0.9 MPa) and low temperature (4°C) (Figure 2b region A, Figure 1 center) should represent optimal conditions to allow solubilisation [15]. The low temperature also ensures stability of soluble collagen at storage temperatures below 10°C [23][24][25][26]. The grey rectangle on Region A (Figure 2b, 0.3-0.9 MPa) points to experimental conditions used in presented work.…”