J. Biol. Chem., Vol. 265, Issue 9, 4853-4858, Mar, 1990

Evidence for the in vivo deamidation and isomerization of an asparaginyl residue in cytosolic serine hydroxymethyltransferase

A Artigues, A Birkett and V Schirch
Department of Biochemistry and Molecular Biophysics, Virginia Commonwealth University, Richmond 23298.

Rabbit liver cytosolic serine hydroxymethyltransferase exists in several subforms which have different isoelectric points. Incubation of the purified enzyme with chymotrypsin cleaves the enzyme at Trp14. The released amino-terminal 14-mer peptide was shown to exist in three forms of equal concentration. The peptides differ in structure only at the asparaginyl residue at position 5. In addition to asparagine at this position we found both aspartyl and isoaspartyl residues. The deamidation of Asn5 does not appear to occur during the purification of the enzyme. The in vitro rate of deamidation of Asn5 in the enzyme is more than 5-fold slower than the rate of deamidation of this residue in the free 14-mer peptide. The isoaspartyl residue at position 5 serves as a substrate for protein carboxyl methyltransferase both in the free 14-mer peptide and the native enzyme. The enzyme which has had the amino-terminal 14 residues removed by digestion with chymotrypsin still exists in several forms with different isoelectric points. Reaction of peptides from this enzyme with carboxyl methyltransferase suggests that there is at least one more asparaginyl residue in this enzyme other than Asn5 which has undergone deamidation with the formation of isoaspartyl bonds.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				G. W. Young, S. A. Hoofring, M. J. Mamula, H. A. Doyle, G. J. Bunick, Y. Hu, and D. W. Aswad Protein L-Isoaspartyl Methyltransferase Catalyzes in Vivo Racemization of Aspartate-25 in Mammalian Histone H2B J. Biol. Chem., July 15, 2005; 280(28): 26094 - 26098. [Abstract] [Full Text] [PDF]

				D. J. Taylor, N. K. Krishna, M. A. Canady, A. Schneemann, and J. E. Johnson Large-Scale, pH-Dependent, Quaternary Structure Changes in an RNA Virus Capsid Are Reversible in the Absence of Subunit Autoproteolysis J. Virol., August 28, 2002; 76(19): 9972 - 9980. [Abstract] [Full Text] [PDF]

				R. Pepperkok, A. Hotz-Wagenblatt, N. Konig, A. Girod, D. Bossemeyer, and V. Kinzel Intracellular Distribution of Mammalian Protein Kinase A Catalytic Subunit Altered by Conserved Asn2 Deamidation J. Cell Biol., February 21, 2000; 148(4): 715 - 726. [Abstract] [Full Text] [PDF]

				C. Fledelius, A. H. Johnsen, P. A.C. Cloos, M. Bonde, and P. Qvist Characterization of Urinary Degradation Products Derived from Type I Collagen. IDENTIFICATION OF A beta -ISOMERIZED ASP-GLY SEQUENCE WITHIN THE C-TERMINAL TELOPEPTIDE (alpha 1) REGION J. Biol. Chem., April 11, 1997; 272(15): 9755 - 9763. [Abstract] [Full Text] [PDF]