Glyceraldehyde 3-phosphate from glycerol

Ricinine.—Ricinine (49), the alkaloid of castor bean plants, is derived from nicotinic acid (28) and quinolinic acid (48), and its formation is intimately associated with the pyridine nucleotide cycle cf. ref. 6. Quinolinic acid is built from a C3 fragment that is formed from glycerol via glyceraldehyde and a C4 unit that is related to succinic or aspartic acids. A recent investigation has confirmed this pathway for ricinine (49) and indicated that dihydroxyacetone phosphate lies between glycerol and glyceraldehyde (loss of tritium from C-2 of labelled glycerol). ... 

In most bacteria and in higher plants nicotinic acid is formed from aspartic acid and a three carbon unit derived from glycerol, probably D-glyceraldehyde-3-phosphate (D 2). A key intermediate is quinolinic acid, which in animals, however, is derived from l-tryptophan (D 21). Nicotinic acid originates from quinolinic acid via nicotinic acid mononucleotide formed with the participation of 5-phosphoribosyl-l-pyrophosphate. It changes either directly to nicotinic acid or is formed via nicotinamide adenine dinucleotide (NAD+) in the nicotinic acid nucleotide cycle. 

L-Fmctose l-Phosphate from L-Clyceraldehyde by in-situ Formation of DHAP. GPO (70 U), catalase (1000 U), and RhuA (50 U) was added to a solution of L-glycerol 3-phosphate (74, 1.0 mmol) and L-glyceraldehyde (110 mg, 1.2 mmol) in 10 mL oxygen-saturated water at pH 6.8. The mixture was shaken at 20 °C under an oxygen atmosphere at 100 rpm. Conversion was monitored by enzymatic assay for equivalents of 41 produced, and by H and NMR spectroscopy. After complete conversion and filtration through charcoal the pH was adjusted to 7.5 by addition of 1.0 m cyclo-hexylamine in ethanol and the solution was concentrated to dryness by rotary evaporation at <20 °C in vacuo. The solid residue was dissolved in 0.5 mL water and the resulting solution was filtered. Dry ethanol (2.5 mL) was added, then dry acetone until faint turbidity remained. Crystallization at 4 °C furnished L-fructose 1-phosphate bis(cyclohexylammonium) salt as colorless needles yield 370 mg (85%). 

Fig. 23. Proposed active site arrangement of sn-glycerol-3-phosphate dehydrogenase (below), based on secondary structure predicted from the known primary structure, and on comparison with the known tertiary structure of glyceraldehyde-3-phosphate dehydrogenase (above). From the work of Rossmann and colleagues (94).

Fructose-l,6-diphosphate (FDP) may also be converted into dihydroxyacetone phosphate (DHAP), which is also synthesized from glyceraldehyde-3-phosphate (GAP). The dihydroxyacetone phosphate (DHAP), thus obtained, is converted into glycerol-3-phosphate (G-3-P), in the presence of cytosolic NADH. The latter gives away one phosphate radical to ADP to generate ATP and glycerol (Chart 1). Thus in the above process, one mole of glucose is converted into two moles of pyruvate with a net gain of two moles of ATP [1],... 

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