Studies on brain cytosol neuraminidase. II. Extractability, solubility and intraneuronal distribution of the enzyme in pig brain

Bruno Venerando, Augusto Preti, Adriana Lombardo, Benvenuto Cestaro, Guido Tettamanti

Research output: Contribution to journalArticlepeer-review

Abstract

The origin and properties of cytosolic neuraminidase (acylneuraminyl hydrolase, EC 3.2.1.18) from pig brains were studied. 1. 1. The brain extracts containing the cytosol derived from neuronal bodies and glial cells carry 0.69 munits neuraminidase/g fresh tissue. The behaviour of neuraminidase during extraction closely paralleled that of authentic cytosolic enzyme, lactate dehydrogenase; whereas, it differed from that of the lysosomal enzymes, β-hexosaminidase and β-galactosidase, also found in the extracts. 2. 2. Nerve endings from either crude or purified preparations, when treated by hypoosmotic shock, released neuraminidase activity up to a maximum of 1.25 munits/g fresh tissue. The behaviour of releasable neuraminidase was always identical to that of lactate dehydrogenase and very similar to that of ATPase and acetylcholinesterase. Typical lysosomal enzymes, however, such as β-galactosidase and β-hexosaminidase, behaved differently under the same conditions. This neuraminidase activity is thought to be derived from the cytosol of nerve endings. 3. 3. The specific activity of neuraminidase in nerve-ending cytosol is 15-20 times that in neuronal body and glial cell cytosol. Some properties (pH, Km value, V/t relationship) of the cytosolic enzymes of different origin are similar; others (stability on standing at 4°C; resistance to freezing and thawing) are different. Hypoionic solutions caused both cytosolic neuraminidases to slowly precipitate and to assume a stable insoluble form which was still active.

Original languageEnglish
Pages (from-to)17-30
Number of pages14
JournalBBA - Enzymology
Volume527
Issue number1
DOIs
Publication statusPublished - Nov 10 1978

ASJC Scopus subject areas

  • Medicine(all)

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