Thermal (In)Stability of Type I Collagen Fibrils

Gevorkian, S. G.; Allahverdyan, Armen E.; Gevorgyan, D.S.; Simonian, Aleksandr

doi:10.1103/physrevlett.102.048101

Cited by 11 publications

(16 citation statements)

References 26 publications

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“…The calculation assumes the typical ∼1000 residue per individual polypeptide chain in a triple helix and a dermal collagen content of 80%. This range of absorbed water is slightly lower, but generally consistent with Gevorkian et al,29 where water content in rat tail tendon at 93% RH was reported at ∼2 mol H 2 O/mol amino acid and the hydration networks of 1–3 mol H 2 O/mol amino acid revealed in x‐ray diffraction studies of collagen‐like peptides 2, 30, 31…”

Section: Resultssupporting

confidence: 88%

Raman microspectroscopic and dynamic vapor sorption characterization of hydration in collagen and dermal tissue

et al. 2011

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Water is an integral part of collagen's triple helical and higher order structure. Studies of model triple helical peptides have revealed the presence of repetitive intrachain, interchain, and intermolecular water bridges (Bella et al., Structure 1995, 15, 893-906). In addition, an extended cylinder of hydration is thought to be responsible for collagen fiber assembly. Confocal Raman spectroscopy and dynamic vapor sorption (DVS) measurements of human Type I collagen and pigskin dermis were performed to probe relative humidity (RH)-dependent differences in the nature and level of collagen hydration. Raman spectra were also acquired as a function of time for both Type I collagen and pigskin dermis samples upon exchange of a 100% RH H(2) O to deuterium oxide (D(2) O) environment. Alterations in Amide I and III modes were consistent with anticipated changes in hydrogen bonding strength as RH increased and upon H → D exchange. Of note is the identification of a Raman spectral marker (band at 938 cm(-1) ) which appears to be sensitive to alterations in collagen-bound water. Analysis of DVS isotherms provided a quantitative measure of adsorbed and absorbed water vapor consistent with the Raman results. The development of a Raman spectral marker of collagen hydration in intact tissue is relevant to diverse fields of study ranging from the evaluation of therapeutics for wound healing to hydration of aging skin.

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Section: Resultssupporting

confidence: 88%

Raman microspectroscopic and dynamic vapor sorption characterization of hydration in collagen and dermal tissue

et al. 2011

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“…This effect was first found in Ref. [18]; it was argued to be related to formation of inter-molecular bonds between partially denaturated fibril constituents. Note that the denaturation temperature of collagen tendon, as measured calorimetrically, is also located around 60 − 70 C when heating under speed larger than 1 C/min [13][14][15][16].…”

mentioning

confidence: 72%

“…5,6 show that when heating at speed 1 C/min the collagen fibril undergoes softening transition at temperatures around T soft = 70 C, where θ has a sharp maximum. We note however that the behavior of the Young's modulus E is more intricate [18] than during the glass transitions in synthetic polymers, e.g., rosin [9,10]. It is seen that for T < T soft , E decreases upon increasing T ; this is a typical scenario for the softening transition.…”

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confidence: 99%

Glassy state of native collagen fibril?

Gevorkian

Allahverdyan

Gevorgyan

et al. 2011

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Our micromechanical experiments show that at physiological temperatures type I collagen fibril has several basic features of the glassy state. The transition out of this state [softening transition] essentially depends on the speed of heating v, e.g., for v = 1 C/min it occurs around 70 C and is displayed by a peak of the internal friction and decreasing Young's modulus. The softening transition decreases by 45 C upon decreasing the heating speed to v = 0.1 C/min. For temperatures 20-30 C the native collagen fibril demonstrates features of mechanical glassines at oscillation frequencies 0.1-3 kHz; in particular, the internal friction has a sharp maximum as a function of the frequency. This is the first example of biopolymer glassines at physiological temperatures, because well-known glassy features of DNA and globular proteins are seen only for much lower temperatures (around 200 K). here-concerning, in particular, the specific role of the hydrated water-the rough physical picture of the glass transition in globular proteins is constructed by an analogy with glass-forming liquids [7,8] and synthetic polymers [9,10]. In particular, it is believed that the largescale conformational motion of proteins freezes at ≈ 200 K, analogously to freezing of cooperative motion in glassforming liquids [7,8] and segmental motion in synthetic polymers [9,10].Thus, the glassy features as such are not important in the native state of globular proteins at physiological temperatures, though the glass transition at much lower temperatures allows to gain some understanding of relevant motions in proteins [7,8].Here we shall demonstrate via micro-mechanical methods that the native type I collagen fibril (made of fibrous protein, type I collagen triple-helices) is in a glassy state at physiological temperatures. This state is displayed via frequency-dependent visco-elastic characteristics (the Young's modulus and the damping decrement) of the native fibril. Upon heating the fibril goes out of the glassy state, a phenomenon known as the softening transition [9,10]. The temperature of this transition depends essentially on the speed of heating, e.g., for the standard heating speed v = 1 C/min it occurs around ≈ 70 C. Note that around 70 C the fibril starts to undergo the denaturation process [13][14][15][16]. This process has been studied by different methods, and some of those methods seems to indicate that this process is inherently irreversible [14]. We saw that upon decreasing the heating speed to v = 0.1 C/min, the softening transition takes place at ≈ 25 C, showing that the glassy features pertain to the native state of the collagen fibril and do not directly relate to its denaturation. We shall also confirm that the glassy features are not seen for the heat-denaturated collagen fibril, and contrast features of the native collagen fibril to those of globular proteins.Type I collagen is the major structural element in the extra-cellular matrix. It forms the basis of fibrous connective tissues, such as tendon, chord, skin, bones, corn...

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“…The axial structure is long-range ordered, but it also contains relatively disordered units [1] , [27] . Laterally, the fibril is an approximately hexagonal microcrystal; the range of the lateral order is much less than the axial order range [26] . Fibrils and microfibrils are stabilized by several different factors: a small number of covalent links between terminal points of collagen triple-helices, carbonyl-water hydrogen-bonds, hydrophobic and van der Waals interaction between triple-helices, etc [1] , [2] .…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

Stabilization and Anomalous Hydration of Collagen Fibril under Heating

et al. 2013

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BackgroundType I collagen is the most common protein among higher vertebrates. It forms the basis of fibrous connective tissues (tendon, chord, skin, bones) and ensures mechanical stability and strength of these tissues. It is known, however, that separate triple-helical collagen macromolecules are unstable at physiological temperatures. We want to understand the mechanism of collagen stability at the intermolecular level. To this end, we study the collagen fibril, an intermediate level in the collagen hierarchy between triple-helical macromolecule and tendon.Methodology/Principal FindingWhen heating a native fibril sample, its Young’s modulus decreases in temperature range 20–58°C due to partial denaturation of triple-helices, but it is approximately constant at 58–75°C, because of stabilization by inter-molecular interactions. The stabilization temperature range 58–75°C has two further important features: here the fibril absorbs water under heating and the internal friction displays a peak. We relate these experimental findings to restructuring of collagen triple-helices in fibril. A theoretical description of the experimental results is provided via a generalization of the standard Zimm-Bragg model for the helix-coil transition. It takes into account intermolecular interactions of collagen triple-helices in fibril and describes water adsorption via the Langmuir mechanism.Conclusion/SignificanceWe uncovered an inter-molecular mechanism that stabilizes the fibril made of unstable collagen macromolecules. This mechanism can be relevant for explaining stability of collagen.

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Thermal (In)Stability of Type I Collagen Fibrils

Cited by 11 publications

References 26 publications

Raman microspectroscopic and dynamic vapor sorption characterization of hydration in collagen and dermal tissue

Raman microspectroscopic and dynamic vapor sorption characterization of hydration in collagen and dermal tissue

Glassy state of native collagen fibril?

Stabilization and Anomalous Hydration of Collagen Fibril under Heating

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