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Kinetic Studies of a (Na + + K + + Mg 2+ ) ATPase in Sugar Beet Roots
Author(s) -
LINDBERG SYLVIA,
HANSSON GUNNAR,
KYLIN ANDERS
Publication year - 1974
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.1399-3054.1974.tb03735.x
Subject(s) - sugar beet , chemistry , enzyme , atpase , substrate (aquarium) , biochemistry , stereochemistry , biology , horticulture , ecology
Kinetic studies of a microsomal, dithiotreitol treated, homogenate from sugar beet roots led to the following conclusions about its ATPase activity: (1) MgATP in complex appears to be the primary substrate for the reaction. The reciprocal equilibrium constant for the binding to the enzyme is estimated to be approximately 0.2 × 10 −3 M . (2) Free ATP acts as a competitive inhibitor of the MgATP. The binding constant is about twice as high as for MgATP. Consequently the enzyme has less affinity for ATP than for MgATP. (3) Free Mg 2+ has little influence on the velocity, as the binding affinity of the enzyme for Mg 2+ is almost negligible.