Development of an immobilized brain glutamine synthetase liquid chromatographic stationary phase for on-line biochemical studies

Glutamine synthetase (GS) plays a key role in the regulation of glutamate a vailability to neurons. In the present study glutamine synthetase was immob ilized on a silica-based immobilized artificial membrane liquid chromatogra phic stationary phase (IAM-SP) to create tile GS-IAM. The stability of GS w as improved hg immobilization, but the enzyme's affinity for the substrates L-glutamate and D-glutamate was significantly decreased. In contrast, immo bilization significantly increased GS sensitivity to inhibition by methioni ne sulfoximine. The GS-IAM was packed into a chromatography column to creat e an immobilized enzyme reactor (GS-IMER). On-line experiments with the GS- IMER demonstrated that the immobilized enzyme was comparable to the non-imm obilized enzyme with regards to retention of activity and selectivity towar d substrates and inhibitors and was reusable for several weeks. (C) 2001 El sevier Science B.V. All rights reserved.