- Isoaspartate
The isoaspartate group is a
functional group inbiochemistry [Clarke S. (1987) "Propensity for spontaneous succinimide formation from aspartyl and asparaginyl residues in cellular proteins", "Int. J., Peptide Protein Res.", 30, 808-821.] [Stephenson RC and Clarke S. (1989) "Succinimide Formation from Aspartyl and Asparaginyl Peptides as a Model for the Spontaneous Degradation of Proteins", "J. Biol. Chem.", 264, 6164-6170.] . Its formation is achemical reaction in which theside chain of anasparagine oraspartic acid residue attacks the followingpeptide group (in black at top right of Figure 1), forming a symmetricsuccinimide intermediate (in red). The symmetry of the intermediate results in two products of itshydrolysis , either aspartate (in black at left) or in iso(Asp), which is a β-amino acid (in green at bottom right). The reaction also results in thedeamidation of the asparagine residue.Kinetics of isoaspartyl formation
Isoaspartyl formation reactions have been conjectured to be one of the factors that limit the useful lifetime of
protein s.Isoaspartyl formation proceeds much more quickly if the asparagine is followed by a small, flexible residue (such as Gly) that leaves the peptide group open for attack. These reactions also proceed much more quickly at elevated
pH (>10) and temperatures.References
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