DL-Allylglycine

In a first set of experiments the posttrial intraperitoneal acute administration of the GAD-inhibitor DL-allylglycine impaired the memory processes of C57BL/6 (C57) mice tested in a passive avoidance apparatus. Memory improvements were, on the contrary, observed following morphine treatment. These effects were dose- and time-dependent. They were, in particular, evident if mice were injected immediately, or 30 min, but not 60 min, after training in the apparatus, and were absent in the no-footshock groups, suggesting lack of proactive effects of the drugs on performance. In a second set of experiments, the posttraining administration of allylglycine, at a per se ineffective dose (5 mg/kg), antagonized the memory improvement exerted by the administration of morphine (0.5 or 1.0 mg/kg). The results support the hypothesis of an involvement of GABAergic mechanisms in the memory consolidation processes, and suggest the possibility that GABAergic systems play a role in the effects of morphine on memory in C57BL/6 mice.

Spontaneous mutants which acquired the ability to utilize d-allylglycine (d-2-amino-4-pentenoic acid) and dl-cis-crotylglycine (dl-2-amino-cis-4-hexenoic acid) but not l-allylglycine or dl-trans-crotylglycine could be readily isolated from Pseudomonas putida mt-2 (PaM1). Derivative strains of PaM1 putatively cured of the TOL (pWWO) plasmid were incapable of forming mutants able to utilize the amino acids for growth; however, this ability could be regained by conjugative transfer of the TOL (pWWO) plasmid from a wild-type strain of mt-2 or of the TOL (pDK1) plasmid from a related strain of P. putida (HS1), into cured recipients. dl-Allylglycine-grown cells of one spontaneous mutant (PaM1000) extensively oxidized dl-allylglycine and dl-cis-crotylglycine, whereas only a limited oxidation was observed toward l-allylglycine and dl-trans-crotylglycine. Cell extracts prepared from PaM1000 cells contained high levels of 2-keto-4-hydroxyvalerate aldolase and 2-keto-4-pentenoic acid hydratase, the latter enzyme showing higher activity toward 2-keto-cis-4-hexenoic acid than toward the trans isomer. Levels of other enzymes of the TOL degradative pathway, including toluate oxidase, catechol-2,3-oxygenase, 2-hydroxymuconic semialdehyde hydrolase, and 2-hydroxymuconic semialdehyde dehydrogenase, were also found to be elevated after growth on allylglycine. Whole cells of a putative cured strain, PaM3, accumulated 2-keto-4-pentenoic acid from d-allylglycine, which was shown to be rapidly degraded by cell extracts of PaM1000 grown on dl-allylglycine. These same cell extracts were also capable of catalyzing the dehydrogenation of d- but not l-allylglycine and were further found to metabolize the amino acid completely to pyruvate and acetaldehyde. Differential centrifugation of crude cell extracts localized d-allylglycine dehydrogenase activity to membrane fractions. The results are consistent with a catabolic pathway for d-allylglycine and dl-cis-crotylglycine involving the corresponding keto-enoic acids as intermediates, the further metabolism of which is effected by the action of TOL plasmid-encoded enzymes.