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Specific Binding of Glycosylated β‐Galactosidase to Bovine Brain Synaptic Membrane
Author(s) -
Naoi M.,
Nagatsu T.
Publication year - 1986
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1986.tb13018.x
Subject(s) - dissociation constant , binding site , synaptic membrane , chemistry , synaptic vesicle , membrane , biochemistry , trypsin , biophysics , beta (programming language) , enzyme , biology , receptor , vesicle , computer science , programming language
The binding of a series of glycosylated β‐ga‐lactosidases to a fraction rich in synaptic membrane of bovine brain was examined. β‐Galactosidase modified with p ‐aminophenyl β‐D‐galactopyranoside (β‐D‐Gal β‐gal) was found the most effective in binding to synaptic membrane, followed by that modified with β‐D‐glucopyranoside, whereas the enzyme modified with p ‐aminophenyl derivatives of α‐D‐galactopyranoside, α‐D‐glucopyranoside, and α‐ and β‐L‐fucopyranoside were found not to bind to the membrane. The binding was dependent on time, temperature, and pH; the maximal binding was obtained within 15 min at 4°C and the optimal pH was approximately 4.0. The binding of β‐D‐Gal β‐gal was inhibited by free p ‐aminophenyl β‐D‐galactopyranoside and by the treatment of synaptic membrane with trypsin or phospholipase A 2 or C. The equilibrium dissociation constant and the maximal concentration of binding sites were determined by Scatchard analysis to be 470 ± 35 n M and 27.5 ± 3.1 pmol/mg protein (n = 1). The results suggest that a specific binding site for the specified carbohydrates exists in synaptic membrane and is involved in the internalization of glycoconjugates into nerve terminals.