Vi. Lushchak et al., EFFECT OF HYPOXIA ON THE ACTIVITY AND BINDING OF GLYCOLYTIC AND ASSOCIATED ENZYMES IN SEA SCORPION TISSUES, Brazilian journal of medical and biological research, 31(8), 1998, pp. 1059-1067
The effect of hypoxia on the levels of glycogen, glucose and lactate a
s well as the activities and binding of glycolytic and associated enzy
mes to subcellular structures was studied in brain, liver and white mu
scle of the teleost fish, Scospaena porcus. Hypoxia exposure decreased
glucose levels in liver from 2.53 to 1.70 mu mol/g wet weight and in
muscle led to its increase from 3.64 to 25.1 mu mol/g wet weight. Maxi
mal activities of several enzymes in brain were increased by hypoxia:
hexokinase by 23%, phosphoglucoisomerase by 47% and phosphofructokinas
e (PFK) by 56%. However, activities of other enzymes in brain as well
as enzymes in liver and white muscle were largely unchanged or decreas
ed during experimental hypoxia. Glycolytic enzymes in all three tissue
s were partitioned between soluble and particulate-bound forms. In sev
eral cases, the percentage of bound enzymes was reduced during hypoxia
; bound aldolase in brain was reduced from 36.4 to 30.3% whereas gluco
se-6-phosphate dehydrogenase fell from 55.7 to 28.7% bound. In muscle
PFK was reduced from 57.4 to 41.7% bound. Oppositely, the proportion o
f bound aldolase and triosephosphate isomerase increased in hypoxic mu
scle. Phosphoglucomutase did not appear to occur in a bound form in li
ver and bound phosphoglucomutase disappeared in muscle during hypoxia
exposure. Anoxia exposure also led to the disappearance of bound fruct
ose-1,6-bisphosphatase in liver, whereas a bound fraction of this enzy
me appeared in white muscle of anoxic animals. The possible function o
f reversible binding of glycolytic enzymes to subcellular structures a
s a regulatory mechanism of carbohydrate metabolism is discussed.