Collagen thermal stability

Why does a reduction of collagen thermal stability by 6°C prevent incorporation of the corresponding mutant molecules into bone matrix ... 

Synthetic peptides have been extensively used to study the thermal stability and folding of the triple helix. These peptides can be synthesized as either single chains or cross-linked peptides. Early on, such peptides were synthesized by polycondensation of tri- or hexapeptides, which led to a broad mass distribution that was difficult to separate. With the advances of solid-phase synthesis methods, peptides with defined chain length became available. The most studied collagen-like peptides are (Gly-Pro-Pro) or (Pro-Pro-Gly) and (Gly-Pro-4(if)Hyp) or (Pro-4(if)Hyp-Gly) with n varying from 5 to 15. Sutoh and Noda" " introduced the concept... 

Flandin F, Buffevant C and Herbage D (1984) A differential scanning calorimetry analysis of the age-related changes in the thermal stability of rat skin collagen. Biochim Biophys Acta 791, 205-211. 

The best thermal stability which is observed does not exceed that of a collagen rod. This allows us to assume that, at these concentrations (a few percent), strong lateral interactions between the collagen rods do not exist. Such interactions would enhance the thermal stability, compared to the single collagen rod (7) leading to a crystalline structure of the gel. 

To study the nucleation step for the folding of collagen, a protocol has been developed for the liquid-phase synthesis by which three peptide strands are covalently linked via a C-terminal branch. 70-73 The C-terminal branch is expected to enhance triple-helical thermal stability, and to provide a model of the disulfide-linked C-terminus of type III collagen. 71 ... 

Bachinger, H. P., and Davis, J. M. (1991). Sequence specific thermal stability of the collagen triple-helix. Int. J. Biol. Macromol. 13, 152-156. 

In dyeing the hair and the suede portion a number of factors must be allowed for. The keratin of the hair contains basically the same amino acids as the collagen of the skin but in a different ratio. The keratin of the hair includes cysteine, which cross-links the polypeptide chain and imparts stability. The collagen of the skin does not have these substances, and the cross-links are made by the tanning agent. On the other hand, only L-hydroxyproline can be found in the collagen. As a result the thermal stability is different, and in addition the isoelectric points of the two polypeptides diverge. 

Examination of type I collagen from a patient with type IV OI revealed normal electrophoretic mobility but altered thermal stability. Which region of the molecule is likely to contain the mutation ... 

Bachinger HP, Morris NP, Davis JM Thermal stability and folding of the collagen triple helix and the effects of mutations in osteogenesis imperfecta on the triple helix of type I collagen., 1/ / J Med Genet 45 152-162,1993. 

The collagen triple helix has a unique CD spectmm. The spectrum shows a positive peak at 220-225 nm, and a negative peak at 195-200 nm. In contrast, the polyproline II helix has a positive peak at 228 nm, and a negative peak at 206 nm. The polyproline II like poly-4-hydroxyproIine helix has a positive peak at 219 nm and a negative peak at 205 nm (13). The thermal stability of the triple helix can be monitored easily by the CD... 

Komsa-Penkova R, Koynova R, Kostov G, Tenchov BG. Thermal stability of calf skin collagen type I in salt solutions. Biochim. Biophys. Acta 1996 1297 171-181. 

They found that in all classes for which data were available, the temperature differences (Ts — To) were essentially constant at 27° d= 3°C. This strongly suggested that differences in thermal stability of the various collagens depend on intramolecular processes rather than intermolecular interactions. And this conclusion, in turn, seemed to make possible a clear choice between collagen structures I and II. 

Why does impaired hydroxylation have such devastating consequences Collagen synthesized in the absence of ascorbate is less stable than the normal protein. Studies of the thermal stability of synthetic polypeptides have been especially informative. Hydroxyproline stabilizes the collagen triple helix by forming interstrand hydrogen bonds. The abnormal fibers formed by insufficiently hydroxylated collagen contribute to the skin lesions and blood-vessel fragility seen in scurvy. 

This finding seems correlated to the thermal stability of host-guest triple helical peptides in collagen and the observed frequency of its amino acid residues (see Table 1 in Persikov et al. (2000)). 

J. R., The efiFect of salicylates on nonenzymatic glycosylation and thermal stability of collagen in diabetic rats. Diabetes 33, 745-751 (1984). 

The Thermal Stability of Collagen Its Significance in Biology and Physiology... 

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