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Effects of oxidants on global phosphatase activity in isolated diaphragm
Author(s) -
Clanton Thomas L,
Wright Valerie P
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.757.35
Subject(s) - chemistry , phosphatase , redox , biochemistry , intracellular , protein tyrosine phosphatase , tyrosine , phosphorylation , inorganic chemistry
Phosphatases are potential cell redox sensors. We hypothesize that skeletal muscle phosphatase (PPase) activity is reduced by exposure to low levels of oxidants. Rat diaphragm bundles were treated with H 2 O 2 (5, 50, 500 μM) or 2,3‐dimethoxy‐1‐naphthoquinone (DMNQ; 1,10, or 100 μM; an intracellular O 2 •− generator). Supernatants were assayed for oxidized proteins, total PPase, serine/threonine PPase (ser/thr‐PPase) or tyrosine PPase (tyr‐PPase) activities. Total PPase activity was significantly reduced at all H 2 O 2 doses, (20% at 500 μM) whereas Ser/thr‐PPase activity was significantly reduced at 50 and 500 μM H 2 O 2 . Total PPase and ser/thr‐PPase activities were significantly reduced at 10μM and 100μM DMNQ, whereas Tyr‐PPase activity decreased significantly at all doses. DTT treatment of supernatants increased all PPase activities but surprisingly did not reverse the dose‐dependent effects of oxidants. Assays of global protein oxidation displayed mild carbonyl formation at 500μM H 2 O 2 but there were no other indications of protein oxidation. The data are consistent with global phosphatase activity being highly sensitive to local cellular redox changes within a near physiologic range. NIH 53333