Duerksen-Hughes PJ, Williamson MM, Wilkinson KD

4-(Oxoacetyl)phenoxyacetic acid (OAPA) forms a stable, covalent bond between its glyoxal group and the guanidino group of arginine and arginine derivatives [Duerksen, P. J., & Wilkinson, K. D. (1987) Anal. Biochem. 160, 444-454]. Studies were carried out to determine the chemical nature of this linkage, and the structure of the ...

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stable adduct between OAPA and methylguanidine was elucidated. The stable product results from an internal oxidation-reduction of the Schiff base adduct to form a cyclic alpha-aminoamide, 4-[4-(carboxymethoxy)phenyl]-2-(methylimino)-5-oxoimidazolidine. OAPA coupled to polyacrylamide beads was used to immobilize ubiquitin via its arginine residues, and the resulting affinity support was shown to specifically and reversibly bind a previously described enzyme, ubiquitin carboxyl-terminal hydrolase [Pickart, C. M., & Rose, I. A. (1985) J. Biol. Chem. 260, 7903-7910]. The resin was then used to isolate three newly identified ubiquitin carboxyl-terminal hydrolytic activities, which did not bind to ubiquitin immobilized via lysine residues. Significant purification was achieved in each case, and one isozyme was further purified to homogeneity.

Date: Oct. 17, 1989

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