Studies of rat brain metabolism using proton nuclear magnetic resonance: spectral assignments and monitoring of prolidase, acetylcholinesterase, and glutaminase.
The first application of inversion-recovery spin-echo proton nuclear magnetic resonance spectroscopy to the monitoring of reactions in rat brain preparations is presented. The initial report of the assignment of proton spin-echo nuclear magnetic resonance spectra from rabbit brain homogenates (C. R. Middlehurst et al., J. Neurochem. 42, 878-879, 1984) was used to assist in the assignment of spectra acquired from rat brain homogenates that were obtained from animals killed by cervical fracture or focussed microwave irradiation. Microwave-irradiated brains were divided into four major anatomical regions. Differences in metabolite levels were detected when spectra from fresh tissue and from various regions were compared. The in situ steady-state kinetics of prolidase in whole brain homogenate was determined. The procedure relies on the spectral differences between enzyme substrates and reaction products. The concentration dependence of the rate of hydrolysis of glycyl-L-proline was discribable by the Michaelis-Menten expression with a Michaelis constant of 1.90 mmol L-1 and a maximal velocity of 9.30 mumol min-1 mg-1 protein. The reactions catalysed by glutaminase and acetylcholinesterase in the brain were also monitored.
D000109:Acetylcholine / Q000378:metabolism; D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D004150:Dipeptidases / Q000378:metabolism*; D005972:Glutaminase / Q000378:metabolism*; D007700:Kinetics; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D011522:Protons; D051381:Rats; D014018:Tissue Distribution
D007773:Lactates; D011522:Protons; D019344:Lactic Acid; D000110:Acetylcholinesterase; D004150:Dipeptidases; C022449:proline dipeptidase; D005972:Glutaminase; D000109:Acetylcholine