Purification and characterization of putrescine synthase from cucumber seedlings. A multifunctional enzyme involved in putrescine biosynthesis

Cadaverine: a lysine catabolite involved in plant growth and development

The cadaverine (Cad) a diamine, imino compound produced as a lysine catabolite is also implicated in growth and development of plants depending on environmental condition. This lysine catabolism is catalyzed by lysine decarboxylase, which is developmentally regulated. However, the limited role of Cad in plants is reported, this review is tempted to focus the metabolism and its regulation, transport and responses, interaction and cross talks in higher plants. The Cad varied presence in plant parts/products suggests it as a potential candidate for taxonomic marker as well as for commercial exploitation along with growth and development.

Agmatine deiminase from cucumber seedlings is a mono-specific enzyme: purification and characteristics

Agmatine deiminase was purified to homogeneity from cucumber seedlings. The purification procedures included treatment with DE52, ammonium sulfate precipitation, DE52 column chromatography, Superdex 200 column chromatography, and agmatine-(CNBr)-diaminohexane-CNBr-activated-Sepharose 4B column chromatography. The purified agmatine deiminase exhibited a specific activity of 242nkat/mg protein at 30 degrees C, pH 7.0, with a yield of 33%. The molecular mass of the native enzyme was 67kDa, as estimated by Superdex 200 column chromatography. On the other hand, SDS-PAGE showed that the molecular masses of the subunits with 1% SDS and 5% of 2-mercaptoethanol treatment and with additional N-glycosidase F treatment were 47 and 36kDa, respectively. These results suggest that agmatine deiminase from cucumber is a glycoprotein. The Km of the enzyme for agmatine was 16microM and arcaine was a potent competitive inhibitor of the enzyme, with a Ki of 7.1microM. The enzyme was stable for 2 months at 4 degrees C. The enzyme does not have putrescine synthase activity or the activities of its components ornithine and putrescine transcarbamylase. The characteristics of the enzyme purified from cucumber were like those of the enzyme from maize. These results indicate that agmatine deiminase is distinctly different from putrescine synthase in higher plants.

Agmatine deiminase from maize shoots: purification and properties

Agmatine deiminase was purified to a specific activity of 537 nkat/mg protein using an improved procedure. The recovery was 47% and the enzyme was homogeneous and remarkably stable. The molecular mass of the enzyme as determined by gel filtration was 75 kDa, and SDS-PAGE suggests that the enzyme is a heterodimer composed of subunits of 43.5 and 44 kDa. The Km for agmatine was 12 microM and arcaine was shown to be a potent competitive inhibitor of the enzyme, with a Ki of 3.3 microM. The enzyme does not have either putrescine synthase activity or the activities of its components ornithine and putrescine transcarbamylase. These results distinctly demonstrate that agmatine deiminase is different from putrescine synthase.