Biomaterial Database

[Regulation of the glyoxylic cycle: effect of the NADPH/NADP ratio]. 1982

A Machado

The utilization of two-carbon sources is carried out through the operation of the glyoxylic acid cycle. The cycle involves several Krebs cycle steps as well as two additional specific enzymes, isocitrate lyase and malate synthase. Kinetic data from the isocitrate transforming enzymes suggest that the flow of isocitrate through the glyoxylic acid cycle depends upon the inhibition of the isocitrate decarboxylating enzymes. Three different mechanisms have been proposed at present that could account for this inhibition: a) Inhibition by concerted action of oxalacetate and glyoxylate; b) NADP-linked isocitrate dehydrogenase phosphorilation in E. coli, and c) competitive inhibition by NADPH with respect to NADP. In the present case the variations of the NADPH/NADP ratio would be channeling the utilization of isocitrate into the glyoxylic acid cycle.

UI	MeSH Term	Description	Entries
D007521	Isocitrate Dehydrogenase	An enzyme of the oxidoreductase class that catalyzes the conversion of isocitrate and NAD+ to yield 2-ketoglutarate, carbon dioxide, and NADH. It occurs in cell mitochondria. The enzyme requires Mg2+, Mn2+; it is activated by ADP, citrate, and Ca2+, and inhibited by NADH, NADPH, and ATP. The reaction is the key rate-limiting step of the citric acid (tricarboxylic) cycle. (From Dorland, 27th ed) (The NADP+ enzyme is EC 1.1.1.42.) EC 1.1.1.41.	NAD Isocitrate Dehydrogenase,Isocitrate Dehydrogenase (NAD+),Isocitrate Dehydrogenase-I,Dehydrogenase, Isocitrate,Dehydrogenase, NAD Isocitrate,Isocitrate Dehydrogenase I,Isocitrate Dehydrogenase, NAD
D007522	Isocitrate Lyase	A key enzyme in the glyoxylate cycle. It catalyzes the conversion of isocitrate to succinate and glyoxylate. EC 4.1.3.1.	Isocitrase,Isocitratase,Lyase, Isocitrate
D007523	Isocitrates	Derivatives of isocitric acid, a structural isomer of CITRIC ACID, including its salts and esters.
D008292	Malate Synthase	An important enzyme in the glyoxylic acid cycle which reversibly catalyzes the synthesis of L-malate from acetyl-CoA and glyoxylate. This enzyme was formerly listed as EC 4.1.3.2.	Glyoxylate Transacetylase,Malate Condensing Enzyme,Malate Synthetase,Condensing Enzyme, Malate,Enzyme, Malate Condensing,Synthase, Malate,Synthetase, Malate,Transacetylase, Glyoxylate
D009249	NADP	Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5'-phosphate (NMN) coupled by pyrophosphate linkage to the 5'-phosphate adenosine 2',5'-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed)	Coenzyme II,Nicotinamide-Adenine Dinucleotide Phosphate,Triphosphopyridine Nucleotide,NADPH,Dinucleotide Phosphate, Nicotinamide-Adenine,Nicotinamide Adenine Dinucleotide Phosphate,Nucleotide, Triphosphopyridine,Phosphate, Nicotinamide-Adenine Dinucleotide
D010071	Oxaloacetates	Derivatives of OXALOACETIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that include a 2-keto-1,4-carboxy aliphatic structure.	Ketosuccinates,Oxosuccinates,Oxaloacetic Acids
D010766	Phosphorylation	The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.	Phosphorylations
D002952	Citric Acid Cycle	A series of oxidative reactions in the breakdown of acetyl units derived from GLUCOSE; FATTY ACIDS; or AMINO ACIDS by means of tricarboxylic acid intermediates. The end products are CARBON DIOXIDE, water, and energy in the form of phosphate bonds.	Krebs Cycle,Tricarboxylic Acid Cycle,Citric Acid Cycles,Cycle, Citric Acid,Cycle, Krebs,Cycle, Tricarboxylic Acid,Cycles, Citric Acid,Cycles, Tricarboxylic Acid,Tricarboxylic Acid Cycles
D006038	Glyoxylates	Derivatives of glyoxylic acid (the structural formula C2H2O3), including its salts and esters.
D001419	Bacteria	One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.	Eubacteria