Thermal stability of bovine-brain myelin membrane |
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Authors: | J Ruiz-Sanz J Ruiz-Cabello O Lopez-Mayorga M Cortijo P L Mateo |
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Institution: | (1) Departamento de Química Fisica (Facultad de Ciencias) e Instituto de Biotecnología, Universidad de Granada, E-18071 Granada, Spain;(2) Departamento de Química Fisica II, Facultad de Farmacia, Universidad Complutense de Madrid, E-28039 Madrid, Spain |
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Abstract: | The thermal behaviour of bovine-brain myelin membrane has been studied by high-sensitivity differential scanning calorimetry, Fourier-transform infrared spectroscopy and thermal gel analysis. Spectroscopic results indicate that protein transitions take place between 60°C and 90°C, while thermal gel analysis has provided the thermal denaturation profiles of myelin proteolipid, DM-20 protein and the Wolfgram Fraction. An irreversible calorimetric transition centred at 80.3 ± 0.2°C with a specific enthalpy of 4.7 ± 0.6 J/g of total protein has been assigned to the thermal denaturation of myelin proteolipid and DM-20 protein. The effects of the myelin storage conditions, scan rate, ionic strength and pH on this calorimetric transition have also been investigated. The thermal transition of the proteolipid practically disappears after treatment of the myelin with different amounts of chloroform-methanol 2:1 (v/v), a treatment which is generally used in proteolipid purification. On the other hand, the addition of several detergents to myelin only causes minor modifications to this transition, which then occurs at about 70°C, with a specific enthalpy of between 2.5 and 3.6 J/g of total protein. These results appear to show that detergents preserve the native conformation of the proteolipid far more than do organic solvents. Hence the use of detergents would seem to be the appropriate method for proteolipid purification.Abbreviations DSC
Differential scanning calorimetry
- TGA
Thermal gel analysis
- FTIR
Fourier-transform infrared spectroscopy
- PLP
Proteolipid protein
- MBP
Myelin basic protein
- DM-20
Protein DM-20
- WF
Wolfgram fraction
- BSA
Bovine serum albumine
- SDS
Sodium dodecyl sulfate
- ANSA
4-amino-3-hydroxynaphthalene-1-sulphonic acid
- OG
-d-glucopyranoside
- PAGE
Polyacrylamide gel electrophoresis
- Chaps
3-(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate
- CNS
Central nervous system
Correspondence to: P. L. Mateo |
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Keywords: | Myelin Proteolipid stability and denaturation Differential scanning calorimetry Thermal gel analysis Fourier-transform infrared spectroscopy |
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