ABSTRACT
Agmatine, which results from the decarboxylation of L-arginine by arginine decarboxylase, is a metabolic intermediate in the biosynthesis of putresine and higher polyamines (spermidine and spermine). Recent studies indicate that agmatine can have several important biochemical effects in humans, ranging from effects on the central nervous system to cell proliferation in cancer and viral replication. Agmatinase catalyses the hydrolysis of agmatine to putresine and urea and is a major target for drug action and development. The human agmatinase gene encodes a 352-residue protein with a putative mitochondrial targeting sequence at the N-terminus. Human agmatinase (residues Ala36-Val352) has been overexpressed as a fusion with both N- and C-terminal purification tags in Escherichia coli and crystallized in the presence of Mn2+ and 1,6-diaminohexane at 297 K using polyethylene glycol 4000 as a precipitant. X-ray diffraction data were collected at 100 K to 2.49 A from a flash-frozen crystal. The crystals are tetragonal, belonging to space group P4(2), with unit-cell parameters a = b = 114.54, c = 125.65 A, alpha = beta = gamma = 90 degrees. Three monomers are likely to be present in the asymmetric unit, giving a crystal volume per protein weight (VM) of 3.66 A3 Da(-1) and a solvent content of 66.4%.
Subject(s)
Crystallography, X-Ray/methods , Ureohydrolases/chemistry , Agmatine/chemistry , Arginine/chemistry , Carboxy-Lyases/chemistry , Catalysis , DNA, Complementary/metabolism , Diamines/chemistry , Escherichia coli/metabolism , Humans , Hydrolysis , Kidney/metabolism , Magnesium/chemistry , Mitochondria/metabolism , Polyethylene Glycols/chemistry , Protein Conformation , Protein Structure, Tertiary , Recombinant Fusion Proteins/chemistry , Spermidine/chemistry , Spermine/chemistry , Temperature , Urea/chemistry , X-Ray DiffractionABSTRACT
The more polar metabolites from the Venezuelan plant Verbesina caracasana, i.e., N(3)-prenylagmatine, (3,4-dimethoxycinnamoyl)-N(1)-agmatine, agmatine, and galegine (prenylguanidine), previously reported (Delle Monache, G.; et al. BioMed. Chem. Lett. 1999, 9, 3249-3254), have been synthesized following a biosynthetic strategy. The pharmacologic profiles of various synthetic analogues of (3,4-dimethoxycinnamoyl)-N(1)-agmatine (G5) were also analyzed, to shed some light on the structure-activity relationship of these compounds. Derivatives with the (E)-configuration and/or with a p-methoxybenzoyl moiety were found to be responsible for higher hypotensive effects, which were associated with a slight and, in some cases, not dose-related increase of cardiac inotropism, with variable and not significant chronotopic responses, and, only at higher doses, with effects of respiratory depression. Either an increase (to six) or a decrease (to two) of the number of methylene groups in the alkyl chain of (E)-G5 did not change blood pressure responses, while slightly increasing the positive inotropic ones. At pharmacological doses, all the studied compounds showed hypotensive and slight positive inotropic effects without relevant chronotropic and respiratory actions.