Tryptophan decarboxylase from Catharanthus roseus is a pyridoxoquinoprotein

Abstract

Tryptophan decarboxylase (EC 4.1.1.28) from Catharanthus roseus was purified to homogeneity. The native enzyme has an M r of about 96000 as estimated from native PAGE. After SDS‐PAGE, three protein bands were visible corresponding with M r 49000, 33000 and 17000. The N‐termini of the 49 kDa protein and the 33 kDa protein were identical. Antibodies against the 49 kDA protein also reacted strongly with the two smaller proteins. It is concluded that the native enzyme consists of two subunits of M r 49000. Tryptophan decarboxylase appears to be a pyridoxo‐quinoprotein, since two molecules of pyridoxal phosphate and two molecules of covalently‐bound pyrroloquinoline quinone were found per enzyme molecule.

Catharanthus terpenoid indole alkaloids: biosynthesis and regulation

“…This enzyme was purified first by Noe and Berlin (1984), later this protein was extensively characterized (Fernandez et al 1989;Pennings et al 1989a, b). The enzyme is a soluble protein consisting of two identical subunits containing two molecules of pyridoxal phosphate (Pennings et al 1989a). It was observed that TDC activity can be induced when suspension cultures of C. roseus are transferred from growth medium to alkaloid induction medium that contains a high concentration of sugar and low levels of hormones, nitrogen and phosphate (Knobloch et al 1981).…”

“…4.1.1.28). This enzyme was purified first by Noe and Berlin (1984), later this protein was extensively characterized (Fernandez et al 1989;Pennings et al 1989a, b). The enzyme is a soluble protein consisting of two identical subunits containing two molecules of pyridoxal phosphate (Pennings et al 1989a).…”

Spatial Organization of Enzymes in Plant Metabolic Pathways

“…In the following narrative, a small sample of specialized pathways is given to illustrate systems where future details of compartmenta tion or other spatial organization of catalytic domains can be anticipated. alkaloid synthesis in plants such as Catharanthus roseus, is a pyridoxo quinoprotein (91). In cases where a high output of indole alkaloids occurs, an understanding of the following aspects is essential: (a) the energy-drain impact of hyperutilization of a quantitatively minor amino acid that requires more energy input for biosynthesis than any of the protein amino acids; (b) the nature of cross-pathway relationships with respect to the role of tyrosine as a precursor of the pyrroloquinoline quinone cofactor needed for tryptophan decarboxylase; and (c) the spatial and metabolic relationship to the pathway of auxin synthesis, which also utilizes tryptophan as the starting precursor.…”

Cell and tissue cultures of Catharanthus roseus: A literature survey

“…2) [for review see Kutchan (1993)]. It consists of two identical subunits containing two molecules of pyridoxal phosphate (Pennings et al 1989a). TDC has been isolated and purified from suspension cultures to apparent homogeneity (Pennings et al 1989b).…”