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Biochemistry, Biophysics, and Structural Biology Commons

Open Access. Powered by Scholars. Published by Universities.®

Biotechnology

1989

Articles 1 - 2 of 2

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Chloroplast Thylakoid Protein Phosphatase Is A Membrane Surface-Associated Activity, Gongqin Sun, Doreen Bailey, Michael W. Jones, John Markwell Jan 1989

Chloroplast Thylakoid Protein Phosphatase Is A Membrane Surface-Associated Activity, Gongqin Sun, Doreen Bailey, Michael W. Jones, John Markwell

Biochemistry -- Faculty Publications

Chloroplast thylakoid protein phosphatase activity was measured using 32P-labeled histone as an exogenous substrate and an assay of the 32P released involving formation of a phosphomolybdate complex and organic extraction. The activity was liberated from wheat (Triticum aestivum) thylakoids by washing the membranes in NaCI-containing solutions followed by centrifugation. The liberated phosphatase activity had a pH optimum of approximately 6.75, was inhibited by addition of 10 millimolar EDTA or EGTA, and was stimulated by addition of millimolar amounts of dithiothreitol, magnesium, manganese, or calcium ions. The rate of thylakoid protein dephosphorylation was decreased following liberation of a ...


Role Of Metabolites In The Reversible Light Activation Of Pyruvate,Orthophosphate Dikinase In Zea Mays Mesophyll Cells In Vivo, Chrissi A. Roeske, Raymond Chollet Jan 1989

Role Of Metabolites In The Reversible Light Activation Of Pyruvate,Orthophosphate Dikinase In Zea Mays Mesophyll Cells In Vivo, Chrissi A. Roeske, Raymond Chollet

Biochemistry -- Faculty Publications

Whole leaf and mesophyll cell concentrations of pyruvate, phosphoenolpyruvate (PEP), ATP, and ADP were determined in Zea mays during the reversible light activation of pyruvate, orthophosphate dikinase in vivo. Mesophyll cell levels of the four metabolites were estimated by extrapolation from values in freeze-quenched leaf samples that were fractionated by differential filtration through nylon mesh nets (adapted from M Stitt, HW Heldt [1985] Planta 164: 179-188). During the 3 minutes required for complete light activation of dikinase, pyruvate levels in the mesophyll cell decreased (from 166 ± 15 to 64 ± 10 nanomoles per milligram of chlorophyll [nmol/mg Chi]) while PEP ...