Post-mortem stability of membrane-associated sialidase activity in brain

• Published in: Neuroscience letters Vol. 107; no. 1-3; p. 267
• Main Authors: Leskawa, K C, Szoke, M, Malone, M J
• Format: Journal Article
• Language: English
• Published: Ireland 15.12.1989
• Subjects: Animals; Brain - enzymology; Male; Neuraminidase - metabolism; Postmortem Changes; Rats; Rats, Inbred Strains; Substrate Specificity
• ISSN: 0304-3940
• DOI: 10.1016/0304-3940(89)90829-X

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.