Characterization of an acid phosphatase responsible for hydrolysis of pyridoxal 5′-phosphate in tobacco plants

Luxurious Nitrogen Fertilization of Two Sugar Cane Genotypes Contrasting for Lignin Composition Causes Changes in the Stem Proteome Related to Carbon, Nitrogen, and Oxidant Metabolism but Does Not Alter Lignin Content

“…GAD is a key enzyme that plays a crucial role in biological metabolic systems as it catalyzes the conversion of L-glutamate or its salts to γ-aminobutyric acid (GABA) and CO 2 by utilizing pyridoxal-5-phosphate (PLP) as a cofactor. 99 In addition, there is an alternative pathway for ammonium uptake, including glutamate dehydrogenase (GDH, EC 1.4.1.2 and EC 1.4.1.4), which uses NADPH as a cofactor. GDH may act as a stress-responsive enzyme 100 and plays a complementary role to the usual GS-GOGAT pathway in the reassimilation of excess ammonia released during stress.…”

“…GOGAT showed increased abundance in IACSP04-627, possibly leading to the accumulation of its substrate, glutamate, which is, in turn, cleaved by glutamate decarboxylase (GAD, EC 4.1.1.15), which also exhibited increased abundance in these plants. GAD is a key enzyme that plays a crucial role in biological metabolic systems as it catalyzes the conversion of l -glutamate or its salts to γ-aminobutyric acid (GABA) and CO 2 by utilizing pyridoxal-5-phosphate (PLP) as a cofactor . In addition, there is an alternative pathway for ammonium uptake, including glutamate dehydrogenase (GDH, EC 1.4.1.2 and EC 1.4.1.4), which uses NADPH as a cofactor.…”

“…A number of α- l -amino acids constitute the backbone of different vitamins . It is known that pyridoxine or pyridoxal-5-phosphate (PLP), the active form of vitamin B6, is an essential cofactor in many enzymatic reactions of all living organisms, including GAD mentioned above. According to Ha et al the second reaction of vitamin B6 biosynthetic pathway is catalyzed by erythronate-4-phosphate dehydrogenase (E4PDH, EC 1.2.1.72), differently accumulated in this study only in the IACSP04-627 genotype.…”

“…According to Ha et al the second reaction of vitamin B6 biosynthetic pathway is catalyzed by erythronate-4-phosphate dehydrogenase (E4PDH, EC 1.2.1.72), differently accumulated in this study only in the IACSP04-627 genotype. Huang et al, studying the effect of abiotic stresses in PLP abundance, found increased production of vitamin B6 in tobacco plants, that may play a crucial role in protecting cells from oxidative stress because B6 exhibits antioxidant activity.…”

Rational Design of High-Performance Donor–Linker–Acceptor Hybrids Using a Schiff Base for Enabling Photoinduced Electron Transfer

“…Due to the important biological functions, ACP was selected as the target analyte in the present work. Considering the principles of PET in D-L-A hybrids, we adopted PLP as a model substrate for ACP due to the following reasons: (a) akin to vitamin C and vitamin E, PLP exhibits strong antioxidant activity and is thus a possible electron donor; (b) the aldehyde (−CHO) group in PLP facilitates the formation of Schiff bases (an aldimine) with primary amino (−NH 2 ) groups, which are capable of constructing a covalently linked D-L-A system; (c) PLP is much more reactive than its hydrolysis product PL, because the phosphate moiety blocks intramolecular hemiacetal formation (furthermore, the equilibrium constants for the Schiff base are 1 to 2 orders of magnitude higher with PLP than with PL); (d) the kinetic parameters of ACP toward PLP are comparable to those of other substrates (e.g., p -nitrophenylphosphate and inorganic pyrophosphate); finally, (e) PLP is cheap, easily accessible, biocompatible, and water-soluble.…”