Post-mortem stability of membrane-associated sialidase activity in brain.
The post-mortem changes in membrane-associated sialidase (N-acetylneuraminosyl glycohydrolase, EC 3.2.1.18) were examined in rat brain obtained and stored in a manner which paralleled neuropathological handling of human brains. When whole brains were held at 4 degrees C in covered containers for varying periods of time (0.67 h), sialidase activity toward endogenous membrane substrate was elevated. This elevated activity was maximal at 8 h of storage and decreased thereafter. The apparent decrease in enzyme activation from 8 to 67 h of storage was not due to a reduction of activity, but was the result of depletion of endogenous membrane substrate, since activity toward exogenous ganglioside remained elevated. The changes were due to whole brain storage at 4 degrees C, and not a result of being stored at -80 degrees C. The post-mortem activation of sialidase was not due to the expression of a new form of the enzyme, since it displayed characteristics similar to those reported previously: (a) membrane gangliosides being the preferred native substrate, and (b) ganglioside GM1 and lactosylceramide being the major hydrolytic products. The results underscore the importance of post-mortem storage conditions when analyzing complex carbohydrates of brain.
Leskawa
K C
KC
Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, KY 40292.
Szoke
M
M
Malone
M J
MJ
D000818:Animals; D001921:Brain / Q000201:enzymology*; D008297:Male; D009439:Neuraminidase / Q000378:metabolism*; D011180:Postmortem Changes; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity
D009439:Neuraminidase