Qin L et al. (2016), Unfolding/Refolding Study on Collagen from Sea ...

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Molecules 2016 Nov 16;2111:. doi: 10.3390/molecules21111546.

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Unfolding/Refolding Study on Collagen from Sea Cucumber Based on 2D Fourier Transform Infrared Spectroscopy.

Qin L , Bi JR , Li DM , Dong M , Zhao ZY , Dong XP , Zhou DY , Zhu BW .

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We aimed to explore the differences of thermal behaviors between insoluble collagen fibrils (ICFs) and pepsin-solubilized collagens (PSCs) from sea cucumber Stichopus japonicus. The unfolding/refolding sequences of secondary structures of ICFs and PSCs during the heating and cooling cycle (5 → 70 → 5 °C) were identified by Fourier transform infrared spectrometry combined with curve-fitting and 2D correlation techniques. ICFs showed a higher proportion of α-helical structures and higher thermostability than PSCs, and thus had more-stable triple helical structures. The sequences of changes affecting the secondary structures during heating were essentially the same between ICFs and PSCs. In all cases, α-helix structure was the most important conformation and it disappeared to form a β-sheet structure. In the cooling cycle, ICFs showed a partially refolding ability, and the proportion of β-sheet structure rose before the increasing proportion of α-helix structure. PSCs did not obviously refold during the cooling stage.

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Genes referenced: LOC100887844

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References [+] :

Brauner, A quantitative reconstruction of the amide I contour in the IR spectra of globular proteins: from structure to spectrum. 2005, Pubmed

	Figure 1. Comparison of DSC heating traces between aqueous 5% dispersions of ICFs (red line) and PSCs (black line).
	Figure 2. IR spectra of ICFs (A-a: original spectra at 5 °C; A-b: second derivative spectra at 5 °C; A-c: FSD spectra at 5 °C; A-d: original spectra at 50 °C; A-e: second derivative spectra at 50 °C; A-f: Fourier self-deconvolved spectra at 50 °C) and PSCs (B-a: original spectra at 5 °C; B-b: second derivative spectra at 5 °C; B-c: FSD spectra at 5 °C; B-d: original spectra at 50 °C; B-e: second derivative spectra at 50 °C; B-f: Fourier self-deconvolved spectra at 50 °C).
	Figure 3. Fourier self-deconvolved infrared spectra in the amide I region of ICFs (A) and PSCs (B) obtained at 5 °C with the resolved underlying bands as deduced through peak-fitting analysis (5% w/v in D2O). The accompanying tables list the positions and relative percent areas of these components.
	Figure 4. Fourier self-deconvolved infrared spectra in the amide I region of ICFs (A: heating; B: cooling) and PSCs (C: heating; D: cooling) (5% w/v in D2O).
	Figure 5. 2D IR synchronous (A) and asynchronous (B) maps of amide I bands of ICFs (5% w/v in D2O) during heating (5 → 70 °C, in increment of 5 °C). Red and blue represent positive and negative correlation peaks, respectively.
	Figure 6. 2D IR synchronous (A) and asynchronous (B) maps of amide I bands of ICFs (5% w/v in D2O) during cooling (70 → 5 °C, in decrement of 5 °C). Red and blue color represent positive and negative correlation peaks, respectively.
	Figure 7. 2D IR synchronous (A) and asynchronous (B) maps of amide I bands of PSCs (5% w/v in D2O) during heating (5 → 70 °C, in increment of 5 °C). Red and blue color represent positive and negative correlation peaks, respectively.
	Figure 8. 2D IR synchronous (A) and asynchronous (B) maps of amide I bands of PSCs (5% w/v in D2O) during cooling (70 → 5 °C, in decrement of 5 °C). Red and blue color represent positive and negative correlation peaks, respectively.