Premium
Effects of phloridzin, metavanadate and oligomycin on membrane bound (Na + + K + + Mg 2+ )ATPase activity in sugar beet roots
Author(s) -
Wingstrand Göran,
Lindberg Sylvia
Publication year - 1982
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1982.tb00348.x
Subject(s) - oligomycin , vanadate , chemistry , atpase , sucrose , sugar beet , biochemistry , enzyme , biology , horticulture
To clarify the reaction mechanism of a (Na + + K + + Mg 2+ )ATPase activity in sugar beet roots ( Beta vulgaris L. cv. Monohill) phloridzin, oligomycin (inhibitors of animal ATPases) and metavanadate (NH 4 VO 3 ) have been used. Kinetic studies showed that: 1) Phloridzin inhibition is uncompetitive with respect to MgATP and not influenced by Na + or K + . 2) This inhibition is only found in preparations made in the absence of sucrose. 3) Oligomycin and vanadate inhibit the ATPase in different ways. Omission of sucrose from the preparation medium favours vanadate inhibition but suppresses oligomycin inhibition. 4) The kinetic pattern of the Na + activation of the ATPase differs in preparations made in the absence and presence of sucrose, but that of K + activation is the same. – These results indicate that inclusion as against omission of sucrose from the preparation medium causes a conformational change of the membrane fragments/vesicles, which then expose different surfaces to the surrounding medium.