A,e-Diaminopimelate

With the exception of some constituents such as high concentrations of calcium, dipicolinic aci d, and in Bacillus sphaericus, a, E-diaminopimelic acid, spore are similar to the vegetative cells in composition. 

FIGURE 22-15 Biosynthesis of six essential amino acids from oxalo-acetate and pyruvate in bacteria methionine, threonine, lysine, isoleucine, valine, and leucine. Here, and in other multistep pathways, the enzymes are listed in the key. Note that L,L-a,e-diaminopimelate, the product of step (HI), is symmetric. The carbons derived from pyruvate (and the amino group derived from glutamate) are not traced beyond this point, because subsequent reactions may place them at either end of the lysine molecule. 

In many organisms the immediate biosynthetic precursor of L-lysine is a,e-diaminopimelic acid (structure below). What type of enzyme would catalyze this reaction what coenzyme would be required and what type of enzyme-substrate complex would be formed ... 

Delipidated bacterial residues of human, bovine, avian, and saprophyte strains were active this can be explained by the fact that these residues contain, essentially, cell walls. It is known that mycobacterial cell-walls are mainly composed of three amino acids (alanine, glutamic acid, and a,e-diaminopimelic acid) linked to a polysaccharide containing arabinose, mannose, galactose, and muramic acid, -i and thus have an over-all composition very similar to that of the water-soluble part of the wax D of human strains. 

Meso-a, e-diaminopimelate decarboxylase Bacillus sphaericus, wheat germ DL-Diaminopimelate Inversion 259, 260... 

Nevertheless, an exception to the general rule of retention has recently been discovered in the form of mcfo-a,e-diaminopimelate decarboxylase from Bacillus sphaerkus (259). This PLP-dependent enzyme, which catalyzes the final step in lysine biosynthesis, is the only known amino acid decarboxylase to operate on an a-carbon having the D-configuiation (264). Inversion of configuration was demonstrated for the enzyme from Bacillus sphaerkus by conducting the decarboxylation reaction in H20 solvent and isolating as product (6I7)-l-[6-2H]lysine [Eq. (50)] ... 

The stereochemistry of meso-a,e-diaminopimelate decarboxylase from a eukaryotic source (wheat germ) also involves inversion of configuration (260). As suggested by Floss and Vederas inversion might be comprehensible if the enzyme evolved from a preexisting L-amino acid decarboxylase in which the dispositions... 

The enzyme a,E-diaminopimelate decarboxylase (EC 4.1.1.20) decar-boxylates the (R) center of (25,6/ )-ffieso-diaminopimelic acid 262 to give lysine 257a (Scheme 69). When this reaction was conducted in and... 

The biosynthesis of lysine in higher plants involves the formation of a, e-diaminopimelate from aspartate and pyruvate. Transamination of this intermediate to the diketo compound and reduction of one carboxyl group to an aldehyde function may produce a compound capable of cyclization via aldol condensation, i.e., the C4 -I- C3 pathway. ... 

There appear to be two pathways for the biosynthesis of lysine among microorganisms. In E. coli there is strong evidence that the diamino dicarboxylic acid, a,e-diaminopimelic acid, is a precursor of lysine. Diaminopimelic acid has been isolated from bacteria - and found to be decarboxylated by a specific decarboxylase occurring in wild-type E. coli. This enzyme has been found to be constitutive rather than adaptive, and it is absent from certain of the lysine auxotrophs. "... 

D,L-a,e-diaminopimelic acid No Rf values Methanol-water-5N HCI pyridine. 80 17.5 2.5 10 Paper No. 1, Whatman, USA Visualization ninhydrin 64 1955 ... 

Regulation of lysine biosynthesis. ASA, aspartate-p-semialdehyde DHDP, dihydrodipicolinate DAP, a, e-diaminopimelate and Hse, homoserine. (1) Aspartate kinase,... 

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