Hydroxyproline and Stability of Collagens.

Gustavson, K. H.; Alfthan, Magnus; Salmenoja, Eeva-Liisa; Burris, R. H.

doi:10.3891/acta.chem.scand.08-1298

Cited by 20 publications

(5 citation statements)

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“…The sequence Pro.Hypro was found to be of frequent occurrence, while the Pro.Gly.X sequence was infrequent. According to Gustavson, the hydrothermal stability of different col lagens is correlated with their hydroxyproline content (170,171). He sug gests that these groups are strongly hydrogen bonded.…”

Section: Structural Analysis Of Proteinsmentioning

confidence: 97%

The Chemistry of Proteins and Peptides

Fraenkel‐Conrat¹

1956

Annu. Rev. Biochem.

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Section: Structural Analysis Of Proteinsmentioning

confidence: 97%

The Chemistry of Proteins and Peptides

Fraenkel‐Conrat¹

1956

Annu. Rev. Biochem.

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“…Nevertheless, it appeared tempting to see whether the metastable precipitates could be described, at least qualitatively, by a Thermo-calc computation if the carbides which are empirically absent were artificially suppressed. This can be done by omitting their Gibbs' energies in establishing the equilibrium, following the example of calculations for the metastable Fe-C-system 14 ).…”

Section: Phase Equilibria In Model Alloysmentioning

confidence: 99%

Calculation of phase equilibria for AISI M2 high‐speed steel

Golczewski

Fischmeister

1992

Steel Research

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Thermo‐calc computations have been made for the iron‐rich corner of the system Fe‐Cr‐Mo‐W‐V‐C to obtain phase equilibria for AISI M2 high‐speed steel (German designation S‐6‐5‐2). The calculations describe the main transformation temperatures of this steel with good accuracy. The phases which are present during austenitization and their volume fractions are also correctly accounted for. The solidification sequence of the M2 steel, and in particular the occurrence of M2C in the ledeburitic eutectic, can be explained if the segregation of alloying elements and carbon in the interdendritic spaces is taken into account. The secondary hardening precipitates can be described in satisfactory approximation on the basis of local two‐phase equilibria between each carbide and the matrix, indicating that their compositions are essentially determined by the nucleation process.

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“…(6) and this value of AH" was used to calculate F a t a series of temperatures by using Eqs. (7) and (2). The calculated values of F were compared to observed values of F , and curve fitting was then carried out to obtain the best value of AH".…”

Section: Ah"mentioning

confidence: 99%

“…(3)] at any temperature becomes Since T , is known, AH" is the only parameter which has to be varied in the curve-fitting procedure [Eq. (7)]. For the transition curves in methanol/acetic acid ( Fig.…”

Section: Comparison Of Helix + Coil Transition Of (L-pro-l-pro-gly) mentioning

confidence: 99%

The triple helix ⇌ coil conversion of collagen‐like polytripeptides in aqueous and nonaqueous solvents. Comparison of the thermodynamic parameters and the binding of water to (L‐Pro‐L‐Pro‐Gly)_n and (L‐Pro‐L‐Hyp‐Gly)_n

Engel¹,

Chen²,

Prockop³

et al. 1977

Biopolymers

222

199

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SynopsisThe collagen-like peptides (r,-Pro-r,-Pro-Gly), and (L-Pro-1.-Hyp-Gly), with n = 5 and 10, were examined in terms of their triple helix +coil transitions in aqueous and nonaqueous solvents. The peptides were soluble in 1,2-propanediol containing 3% acetic acid and they were found to form triple-helical structures in this solvent system. The water content of the solvent system and the amount of water bound to the peptides were assayed by equilibrating the solvent with molecular sieves and carrying out Karl Fischer titrations on the solvent phase. After the solvent was dehydrated, much less than one molecule of water per tripeptide unit was bound to the peptides. Since the peptides remained in a triple-helical conformation, the results indicated that water was not an essential component of the triple-helical structure. Comparison of peptides with the same chain length demonstrated that the presence of hydroxyproline increased the thermal stability of the triple helix even under anhydrous conditions. The results, therefore, did not support recent hypotheses that hydroxyproline stabilizes the triple helix of collagen and collagen-like peptides by a specific interaction with water molecules. Analysis of the thermal transition curves in several solvent systems showed that although the peptides containing hydroxyproline had t , values which were 18.6' to 32.7"C higher, the effect of hydroxyproline on AG was only 0.1 to 0.3 kcal per tripeptide unit a t 25°C. The results suggested, therefore, that the influence of hydroxyproline on helical stability may he explained by intrinsic effects such as dipole-dipole interactions or by changes in the solvation of the peptides by alcohol, acetic acid, and water. A direct calorimetric measurement ofthe transition enthalpy for (IA-Pro-r,-Pro-Gly), in 3% or 1 O O h acetic acid gave a value of -1.84 kcal per tripeptide unit for the coil-to-helix transition. From this value for enthalpy and from data on the effects of different chain lengths on the thermal transition, it was calculated that the apparent free energy for nucleation was +5 kcal/mol at 25°C (apparent nucleation parameter = 2 X lo-" M-". The value was dependent on solvent and on chemical modification of end groups.

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Hydroxyproline and Stability of Collagens.

Cited by 20 publications

References 0 publications

The Chemistry of Proteins and Peptides

The Chemistry of Proteins and Peptides

Calculation of phase equilibria for AISI M2 high‐speed steel

The triple helix ⇌ coil conversion of collagen‐like polytripeptides in aqueous and nonaqueous solvents. Comparison of the thermodynamic parameters and the binding of water to (L‐Pro‐L‐Pro‐Gly)_n and (L‐Pro‐L‐Hyp‐Gly)_n

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Hydroxyproline and Stability of Collagens.

Cited by 20 publications

References 0 publications

The Chemistry of Proteins and Peptides

The Chemistry of Proteins and Peptides

Calculation of phase equilibria for AISI M2 high‐speed steel

The triple helix ⇌ coil conversion of collagen‐like polytripeptides in aqueous and nonaqueous solvents. Comparison of the thermodynamic parameters and the binding of water to (L‐Pro‐L‐Pro‐Gly)n and (L‐Pro‐L‐Hyp‐Gly)n

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The triple helix ⇌ coil conversion of collagen‐like polytripeptides in aqueous and nonaqueous solvents. Comparison of the thermodynamic parameters and the binding of water to (L‐Pro‐L‐Pro‐Gly)_n and (L‐Pro‐L‐Hyp‐Gly)_n