Modifications of Long‐Lived Proteins that Affect Protein Solubility

David, Larry L.

doi:10.1002/9783527826759.ch5

Cited by 1 publication

(1 citation statement)

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“…The reason for performing these experiments on the different lens fractions was to determine if the degree of cleavage may be associated with protein solubility in the lens. Data from other studies indicate that crystallin insolubility with age can be traced to a larger extent of protein modification. The results can be found in Figure .…”

Section: Resultsmentioning

confidence: 90%

Spontaneous Cleavage at Glu and Gln Residues in Long-Lived Proteins

et al. 2021

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Long-lived proteins (LLPs) are prone to deterioration with time, and one prominent breakdown process is the scission of peptide bonds. These cleavages can either be enzymatic or spontaneous. In this study, human lens proteins were examined and many were found to have been cleaved on the C-terminal side of Glu and Gln residues. Such cleavages could be reproduced experimentally by in vitro incubation of Glu- or Gln-containing peptides at physiological pHs. Spontaneous cleavage was dependent on pH and amino acid sequence. These model peptide studies suggested that the mechanism involves a cyclic intermediate and is therefore analogous to that characterized for cleavage of peptide bonds adjacent to Asp and Asn residues. An increased amount of some Glu/Gln cleaved peptides in the insoluble fraction of human lenses suggests that cleavage may act to destabilize proteins. Spontaneous cleavage at Glu and Gln, as well as recently described cross-linking at these residues, can therefore be added to the similar processes affecting long-lived proteins that have already been documented for Asn and Asp residues.

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Section: Resultsmentioning

confidence: 90%