Folate Status and Age Affect the Accumulation of L-Isoaspartyl Residues in Rat Liver Proteins
Resource
Journal of Nutrition 132 (6): 1357-1360
Journal
Journal of Nutrition
Journal Volume
132
Journal Issue
6
Pages
1357-1360
Date Issued
2002
Date
2002
Author(s)
Abstract
Formation 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.
Subjects
Folate; L-isoaspartyl; Protein L-isoaspartyl methyltransferase; Rats; S-adenosyl-L-methionine
Other Subjects
aspartic 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 187
Type
journal article
File(s)![Thumbnail Image]()
Loading...
Name
10.pdf
Size
137.06 KB
Format
Adobe PDF
Checksum
(MD5):81dac5fe718ebc677e649517c03822ff