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Partial Purification and Characterization of Detergent‐Solubilized N ‐Sulfotransferase Activity Associated with Calf Brain Microsomes
Author(s) -
Miller R. Robert,
Waechter Charles J.
Publication year - 1988
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.1471-4159.1988.tb04839.x
Subject(s) - microsome , solubilization , chemistry , biochemistry , chromatography , sulfotransferase , sulfation , enzyme
Calf brain 3′‐phosphoadenosine 5′‐phosphosul‐fate (PAPS):proteoheparan sulfate (PHS) N ‐sulfotransfer‐ase activity is solubilized by extracting salt‐washed microsomes with 1% Cutscum. A protocol is described for the partial purification of the sulfotransferase activity utilizing: (1) diethylaminoethyl (DEAE)‐Sephacel, (2) heparin‐Sepharose CL‐6B, and (3) 3′,5′‐ADP‐agarose as chromato‐graphic supports. Sulfotransferase activity was followed by using 3′‐phosphoadenosine 5′‐phospho[ 35 S]sulfate and endogenous acceptors in heat‐inactivated microsomes as exogenous substrates. Two chromatographically distinct fractions (ST 1 and ST 2 ) of sulfotransferase activity are resolved on DEAE‐Sephacel. Both sulfotransferase activities have been partially purified and characterized. An apparent purification of the two N ‐sulfotransferase fractions of 22– to 29‐fold, relative to the microsomal activity, is achieved by this procedure. Since ST 1 appears to represent approximately 24% of the total microsomal activity, a purification of 89‐fold has been estimated for this fraction. Neither sulfotransferase activity was stimulated by MnCl 2 , MgCl 2 , or CaCl 2 added at 10 m M , nor inhibited by the presence of 10 m M EDTA. ST 1 and ST 2 are optimally active at pH 7.5–8. Apparent K m values for PAPS of 2.3 μ M and 0.9 μ M have been determined for ST 1 and ST 2 , respectively. ST 1 exhibits N ‐sulfotransferase activity primarily and is inhibited by phosphatidylserine whereas the ST 2 fraction contains a mixture of N‐ and O ‐sulfotransferase activity and is stimulated by phosphatidylserine, phosphatidylcholine, and ly‐sophosphatidylcholine. The detection of two chromatographically distinct sulfotransferase activities raises the possibility that N‐sulfation of proteoheparan sulfates could be catalyzed by more than one enzyme, and that N‐sulfation and O‐sulfation of proteoglycans are catalyzed by separate enzymes in nervous tissue.