PIMT-Mediated Labeling of l-Isoaspartic Acid with Tris Facilitates Identification of Isomerization Sites in Long-Lived Proteins.

ABSTRACT: Isomerization of individual residues in long-lived proteins (LLPs) is a subject of growing interest in connection with many age-related human diseases. When isomerization occurs in LLPs, it can lead to deleterious changes in protein structure, function, and proteolytic degradation. Herein, we present a novel labeling technique for rapid identification of l-isoAsp using the enzyme protein l-isoaspartyl methyltransferase (PIMT) and Tris. The succinimide intermediate formed during reaction of l-isoAsp-containing peptides with PIMT and S-adenosyl methionine (SAM) is reactive with Tris base and results in a Tris-modified aspartic acid residue with a mass shift of +103 Da. Tris-modified aspartic acid exhibits prominent and repeated neutral loss of water when subjected to collisional activ

SUBMITTER: Silzel JW 

PROVIDER: S-EPMC9930442 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature