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Research has been conducted on amadoriases I and II, Aspergillus sp. deglycation isoenzymes. The effect of arginine residues on amadoriase II binding site has been investigated via the use of arginine modification reagent p-hydroxyphenylglyoxal and the results are reported.

Escherichia coli expressed human recombinant doppel protein domain is an alpha-helical protein with 40% helical content. The domain protein is soluble, proteinase K sensitive, and undergoes reversible cooperative thermal denaturation suggesting that it is similar to the newly recognized prion protein.

Research has been conducted on the amadoriase cloning. Aspergillus fumigatus cDNA library preparation and clone isolation by means of the amplified by polymerase chain reaction probe are examined.

Research has been conducted on the transition mechanism between the normal and pathological isoforms of prion protein. Characterization of the biophysical properties of the recombinant protein is discussed.

Investigates the alteration of substrate selectivity through mutation of two arginine residues in the binding site of Amadoriase II. Treatment of diabetic complications resulting from excessive protein glycation; Inhibition of enzyme activity toward fructosylglycine; Details on peptide mapping and subsequent mass spectrometry analysis.

We have previously reported that amyloid Abeta, the major component of senile plaques in Alzheimer's disease (AD), binds Cu with high affinity via histidine and tyrosine residues [Atwood, C. S., et al. (1998) J. Biol. Chem. 273, 12817-12826; Atwood, C. S., et al. (2000) J. Neurochem. 75, 1219-1233] and produces H(2)O(2) by catalyzing the reduction of Cu(II) or Fe(III) [Huang, X., et al. (1999) Biochemistry 38, 7609-7616; Huang, X., et al. (1999) J. Biol. Chem. 274, 37111-37116]. Incubation with Cu induces the SDS-resistant oligomerization of Abeta [Atwood, C. S., et al. (2000) J. Neurochem. 75, 1219-1233], a feature characteristic of neurotoxic soluble Abeta extracted from the AD brain. Since residues coordinating Cu are most vulnerable to oxidation, we investigated whether modifications of these residues were responsible for Abeta cross-linking. SDS-resistant oligomerization of Abeta caused by incubation with Cu was found to induce a fluorescence signal characteristic of tyrosine cross-linking. Using ESI-MS and a dityrosine specific antibody, we confirmed that Cu(II) (at concentrations lower than that associated with amyloid plaques) induces the generation of dityrosine-cross-linked, SDS-resistant oligomers of human, but not rat, Abeta peptides. The addition of H2O2 strongly promoted Cu-induced dityrosine cross-linking of Abeta1-28, Abeta1-40, and Abeta1-42, suggesting that the oxidative coupling is initiated by interaction of H2O2 with a Cu(II) tyrosinate. The dityrosine modification is significant since it is highly resistant to proteolysis and is known to play a role in increasing structural strength. Given the elevated concentration of Cu in senile plaques, our results suggest that Cu interactions with Abeta could be responsible for causing the covalent cross-linking of Abeta in these structures.