Protein gamma-radiolysis in frozen solutions is a macromolecular surface phenomenon: fragmentation of lysozyme, citrate synthase and alpha-lactalbumin in native or denatured states.
Int J Radiat Biol
; 76(5): 673-81, 2000 May.
Article
em En
| MEDLINE
| ID: mdl-10866290
ABSTRACT
PURPOSE:
To test whether radiolysis-induced fragmentation in frozen aqueous protein solution is dependent on solvent access to the surface of the protein or to the molecular mass of the polypeptide chain. MATERIALS ANDMETHODS:
60Co gamma-irradiation of three proteins at -78 degrees C lysozyme, citrate synthase and alpha-lactalbumin in their native state, with or without bound substrate, or denatured (random coil in urea/acid-denatured state).RESULTS:
By SDS-polyacrylamide gel electrophoresis/analysis of the protein-fragmentation process, it was found that for a given protein D37 values (dose to decrease the measured amount of protein, with an unaltered polypeptidic chain, to 37% of the initial amount) varied according to the state of the protein. D37 for denatured proteins was always much smaller than for native states, indicating a greater susceptibility to fragmentation. In urea, contrary to the native state, no well-defined fragments were observed. Radiolysis decay constants (K= 1/D37) increased with solvent-accessible surface area of these proteins estimated from their radii of gyration in the various states. This is shown also in previous data on native or SDS-denatured proteins. Denatured proteins which have a large surface area exposed to the solvent compared with native ones are more fragmented at equal doses.CONCLUSIONS:
It is concluded that D37 is directly related to the exposed surface area and not to the molecular mass of the polypeptide chain.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Muramidase
/
Citrato (si)-Sintase
/
Lactalbumina
Tipo de estudo:
Risk_factors_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
2000
Tipo de documento:
Article