Serine transhydroxymethylase. Studies on the role of tetrahydrofolate.

摘要: Abstract Studies of the reversible interconversion glycine and serine catalyzed by rabbit liver transhydroxymethylase in presence absence tetrahydrofolate are described. The studies include measurements pH-rate profiles, isotope effects, spectral properties enzyme-substrate complexes. Vmax, values for synthesis from formaldehyde exchange 2S proton with protons solvent were found to be constant between pH 6.0 8.0. Vmax degradation decreased as was increased 8.4. A dissociable group on enzyme a pK about 7 appears involved. An effect 2 [2S-2H]glycine both tetrahydrofolate. rate is limited at high concentration nonenzymatic formation 5,10-methylenetetrahydrofolate. That can react directly enzyme-glycine complex suggested rapid quenching 495-nm 343-nm absorption peaks this formaldehyde. Spectral evidence (the appearance maxima 343 nm 495 above 8 solutions serine) suggests that cleaved an data interpreted support mechanism which bound imine active site. role catalyzing or breakdown intermediate through