Format

Send to

Choose Destination
Arch Biochem Biophys. 2006 May 15;449(1-2):1-7. Epub 2006 Mar 27.

Effects of proteolysis and reduction on phosphatase and ROS-generating activity of human tartrate-resistant acid phosphatase.

Author information

1
Institute of Biomedicine, Department of Anatomy, University of Turku, Turku, Finland. katja.fagerlund@utu.fi

Abstract

Osteoclasts and macrophages express high amounts of tartrate-resistant acid phosphatase (TRACP), an enzyme with unknown biological function. TRACP contains a disulfide bond, a protease-sensitive loop peptide, and a redox-active iron that can catalyze formation of reactive oxygen species (ROS). We studied the effects of proteolytic cleavage by trypsin, reduction of the disulfide bond by beta-mercaptoethanol, and reduction of the redox-active iron by ascorbate on the phosphatase and ROS-generating activity of baculovirus-generated recombinant human TRACP. Ascorbate alone and trypsin in combination with beta-mercaptoethanol increased k(cat)/K(m) of the phosphatase activity seven- to ninefold. The pH-optimum was changed from 5.4-5.6 to 6.2-6.4 by ascorbate and trypsin cleavage. Trypsin cleavage increased k(cat)/K(m) of the ROS-generating activity 2.5-fold without affecting the pH-optimum (7.0). These results suggest that the protease-sensitive loop peptide, redox-active iron, and disulfide bond are important regulatory sites in TRACP, and that the phosphatase and ROS-generating activity are performed with different reaction mechanisms.

PMID:
16620768
DOI:
10.1016/j.abb.2006.03.010
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center