Premium
Mechanisms of Immediate Temperature Compensation: Experiments with Brain Synaptosomes from Rat and Ground Squirrel
Author(s) -
MARJANOVIĆ MARINA,
ŽIVADINOVIĆ DRAGOSLAVA,
DŽAKULA ŽELJKO,
ANDJUS RADOSLAV K.
Publication year - 2005
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1342.005
Subject(s) - ground squirrel , chemistry , synaptosome , hypothermia , biophysics , kinetic energy , substrate (aquarium) , enzyme , biochemistry , medicine , biology , ecology , physics , quantum mechanics , membrane
A bstract : Glucose conversion by brain synaptosomes can be regarded as a special case of intrinsic kinetic properties of the enzyme substrate system. Temperature modulation of apparent K m for this process can be described with our kinetic model. Using experimental data and the kinetic model, the minimal K m value for glucose conversion in ground squirrel synaptosomes was found at the lower temperature (6.5°C), much lower than that for the rat (16.6°C). The inversion temperatures ( T min ) closely coincided with the lowest body temperatures from which the unassisted recovery from hypothermia was demonstrated in both species. This study indicated that thermal modulation of enzyme affinities may have an adaptive role in endotherms that is linked to their tolerance to hypothermia.