Scattering kinetics in a complex tryptophan hydroxylase preparation from rat brainstem raphe nuclei: statistical evidence that the lithium-induced sigmoid velocity function reflects two states of available catalytic potential.
Multiple measures on statistical patterns from a kinetic scattering paradigm for the activities of rat brainstem medial and dorsal raphé nuclear tryptophan hydroxylase preparations are consistent with the previous hypothesis (J. Neural Transmission 45: 1-15, 1979) that the lithium ion induces a state of kinetic bistability in the system. In this context, the lithium-induced sigmoid tetrahydrobiopterin-reaction velocity function is interpreted as a jump between two stable states of differing catalytic potential with a less kinetically accessible domain between them. These dynamics are qualitatively portrayed in three dimensions by Thom's classical cusp catastrophe.
D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives / Q000378:metabolism; D001933:Brain Stem / Q000187:drug effects*; D002384:Catalysis; D007700:Kinetics; D008094:Lithium / Q000494:pharmacology*; D008297:Male; D011903:Raphe Nuclei / Q000187:drug effects* / Q000201:enzymology; D051381:Rats; D011919:Rats, Inbred Strains; D013223:Statistics as Topic; D014364:Tryptophan / Q000378:metabolism; D014365:Tryptophan Hydroxylase / Q000378:metabolism*
D001708:Biopterins; D014364:Tryptophan; D008094:Lithium; D014365:Tryptophan Hydroxylase; C003402:sapropterin