Ghandour, HaifaHaifaGhandourLin, Bi-FongBi-FongLinChoi, Sang-WoonSang-WoonChoiMason, Joel BJoel BMasonSelhub, JacobJacobSelhub2009-07-232018-07-062009-07-232018-07-06200200223166https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036273830&doi=10.1093%2fjn%2f132.6.1357&partnerID=40&md5=ba1381341bf3c2381a19fe294c63ae9ehttp://ntur.lib.ntu.edu.tw//handle/246246/162583http://ntur.lib.ntu.edu.tw/bitstream/246246/162583/1/10.pdfFormation of atypical L-isoaspartyl residues in proteins and peptides is a common, spontaneous and nonenzymatic modification of aspartyl and asparaginyl sites. The enzyme protein-L-isoaspartyl methyltransferase (PIMT) catalyzes the transfer of the methyl group of S-adenosyl-L-methionine (SAM) to these L-isoaspartyl sites, thereby allowing reisomerization and restoration of the original alpha peptide linkage. Because SAM is in part a product of folate metabolism, the present study was undertaken to determine the effects of folate deficiency on the presence of L-isoaspartyl residues in hepatic proteins. Young (weanling) and older (12 mo) Sprague-Dawley rats were fed a folate-sufficient (2 mg folate/kg diet) or folate-deficient (0 mg folate/kg diet) diet for 20 wk. Liver proteins were analyzed for L-isoaspartyl residues. This analysis was based on the PIMT-dependent incorporation of [3H]-methyl groups from [3H]-SAM and the subsequent (nonenzymatic) sublimation of these methyl groups into a nonaqueous scintillant. The amount of L-isoaspartyl residues in hepatic proteins was higher in younger folate-deficient than in folate-sufficient rats (deficient: 187 ± 71, sufficient: 64 ± 43 pmol/mg protein, P < 0.025). This difference, however, was not seen among the older groups of rats who instead exhibited a much larger accumulation of L-isoaspartyl residues in their hepatic proteins (deficient: 528 ± 151, sufficient: 470 ± 204 pmol/mg protein, P = 0.566). The importance of these observations is discussed.application/pdf140353 bytesapplication/pdfen-USFolate; L-isoaspartyl; Protein L-isoaspartyl methyltransferase; Rats; S-adenosyl-L-methionineaspartic acid; folic acid; liver protein; protein isoaspartyl methyltransferase; s adenosylmethionine; unclassified drug; aging; animal experiment; animal model; animal tissue; article; controlled study; folate metabolism; folic acid deficiency; male; nonhuman; protein binding; protein modification; rat; Animalia; Staphylococcus phage 187journal article120424582-s2.0-0036273830WOS:000176033300042http://ntur.lib.ntu.edu.tw/bitstream/246246/162583/1/10.pdf