Destabilization of osteogenesis imperfecta collagen-like model peptides correlates with the identity of the residue replacing glycine
AUTOR(ES)
Beck, Konrad
FONTE
The National Academy of Sciences
RESUMO
Mutations resulting in replacement of one obligate Gly residue within the repeating (Gly-Xaa-Yaa)n triplet pattern of the collagen type I triple helix are the major cause of osteogenesis imperfecta (OI). Phenotypes of OI involve fragile bones and range from mild to perinatal lethal. In this study, host–guest triple-helical peptides of the form acetyl-(Gly-Pro-Hyp)3-Zaa-Pro-Hyp-(Gly-Pro-Hyp)4-Gly-Gly-amide are used to isolate the influence of the residue replacing Gly on triple-helix stability, with Zaa = Gly, Ala, Arg, Asp, Glu, Cys, Ser, or Val. Any substitution for Zaa = Gly (melting temperature, Tm = 45°C) results in a dramatic destabilization of the triple helix. For Ala and Ser, Tm decreases to ≈10°C, and for the Arg-, Val-, Glu-, and Asp-containing peptides, Tm < 0°C. A Gly → Cys replacement results in Tm < 0°C under reducing conditions but shows a broad transition (Tm ≈ 19°C) in an oxidizing environment. Addition of trimethylamine N-oxide increases Tm by ≈5°C per 1 M trimethylamine N-oxide, resulting in stable triple-helix formation for all peptides and allowing comparison of relative stabilities. The order of disruption of different Gly replacements in these peptides can be represented as Ala ≤ Ser < CPOred < Arg < Val < Glu ≤ Asp. The rank of destabilization of substitutions for Gly in these Gly-Pro-Hyp-rich homotrimeric peptides shows a significant correlation with the severity of natural OI mutations in the α1 chain of type I collagen.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=18226Documentos Relacionados
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