L-Lysine metabolism

R. D. Kiss and G. N. Stephanopolous, Metabolic activity control of the L-lysine fermentation by restrained growth fed-batch strategies, Biotechnol Prog. 7, 501-509 (1991). 

Fluoropyruvate inhibits an enzyme which is located on a bypass of lysine metabolism, with the result that more carbon flows towards lysine. The yield was increased to 50 g L 1. 

Becker J, Klopprogge C, Herold A et al (2007) Metabolic flux engineering of L-lysine production in Corynebacterium glutamicum-over expression and modification of G6P dehydrogenase. J Biotechnol 132 99-109... 

Wittmann C, Becker J (2007) The L-lysine story from metabolic pathways to industrial production. In Wendisch VF (ed) Amino acid biosynthesis - pathways, regulation and metabolic engineering. Springer, Berlin... 

Originally polymers of L-lysine were used but because this is the metabolically active form of the amino acid, some workers prefer to use poly-D-lysine. A simple procedure for coating surfaces follows. 

Figure 47-SO The major metabolic pathways for the use of ammonia by the hepatocyte. Solid bars indicate the sites of primary enzyme defects in various metabolic disorders associated with hyperammonemia /) carbamyl phosphate synthetase I, (2) ornithine transcarbamylase, (3) argininosuccinate synthetase, (4) argininosuccinate lyase, (5) arginase, (6) mitochondrial ornithine transport, (7) propionyi CoA carboxylase, (fi) methylmalonyl CoA mutase, (9) L-lysine dehydrogenase, and (10) N-acetyl glutamine synthetase. Dotted lines indicate the site of pathway activation (+) or inhibition ( ). (From Flannery OB, Hsia YE, Wolf 6. Current status of /lyperommofiemjo syndromes. Hepatology 1982 2 495-506,)...

As with glutamic acid production, some modification of the normal metabolic pathway of C. glutamicum imposed by the fermentation conditions, is necessary in order to accumulate lysine in the medium. At present, worldwide production of L-lysine by fermentation routes totals some 70,000 tonnes annually, about 40% of this by Japan. About 9,000 tonnes of racemic lysine (DL mixture) per year is also produced synthetically from petrochemical sources. One interesting synthetic substrate for DL-lysine is caprolactam (or 6-amino-caproic acid), a starting material, which is readily available on a tonnage scale from its use as a nylon monomer. 

Colombo et al. (C9) offered two facts to support their hypothesis. Oral ingestion of lysine by the patient resulted in a marked decrease to zero levels of arginase in the patient s red cells, coincident with the rise in blood lysine to 12.6 mg from 4.4 mg/100 ml. No such decrease was found in a control child or in the parents of the affected infant. There was a moderate decrease when the affected child was given L-arginine or L-leucine. Second, a low activity, 22% of the mean normal, of L-lysine NAD oxidoreductase was found in the liver. The authors suggested that the low activity of this enzyme responsible for the first step in the metabolism of lysine accounted for the accumulation of the latter in the blood. 

A simple assay based on potent and specific inhibition of jack bean a-mannosidase has been devised for determining low concentrations of 162 (up to 0.5 cm ) in M anisopliae cultures (110). The new assay was used to demonstrate that the addition of L-lysine (163) to the culture medium stimulated production of the alkaloid by approximately fourfold. Other early metabolic precursors of 162 in this fungus, including a-aminoadipic acid, saccharopine (164), L-pipecolic acid (165), and L-lysine itself, were quantified by reverse-phase HPLC analysis of mycelial extracts derivatised with 9-fluorenylmethyl chloroformate (FMOC) (111). 

N, 6-N-di(2,3-dihydroxybenzoyl)-L-lysine (58) is a siderophore produced by Azotobacter vinelandii which has only two catechol groups. However, of the catecholate siderophores by far the best studied is enterobactin. A major difference between hydroxamate and catecholate siderophores occurs in their utilization as transport agents. For the former, the iron complex is taken up by the bacterial cell, the iron released, and the hydroxamate siderophore re-secreted for additional iron chelation. In contrast, enterobactin is destroyed by enzymatic hydrolysis within the cell and therefore the ligand is not recycled. This hydrolysis of the amide linkages of the iron(III) enterobactin lowers the redox potential of the chelate complex sufficiently to allow iron reduction — and thus uptake of iron into the cell metabolism (59, 60). 

The urinary elimination of glutaric acid increases in rats after administration of L-lysine (T15), a fact which is in accordance with the known metabolic route leading from lysine to glutaric acid via pipecolic acid (R8) (Fig. 5). Another intermediate of that metabolic sequence, a-keto-adipic acid, is foimd in urine after administration of lysine to the rat, the amount representing about 2 % of that of the administered L-lysine... 

The initial step in the microbiological metabolism of lysine to acetate, butyrate, and ammonia is the reversible interconversion of L-lysine and L-jS-lysine via exchange of the a-amino group and a /8-proton catalyzed by lysine 2,3-aminomutase (Scheme 49). The reaction has been observed in several species of Clostridium, Nocardia, and Streptomyces (218, 219), but the mechanistic studies have concentrated on the enzyme from Clostridium subterminale SB4, which has been purified and characterized (220). The enzyme is extremely sensitive to reversible oxygen inactivation, with reactivation achieved by anaerobic incubation with a thiol and Fe(II), and a protein-bound Fe(II) is apparently required for activity (220). The exchange reaction is also accelerated by S-... 

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