Diaminopimelic acids

AMP, ADP, and ATP = adenosine mono-, di-, and triphosphate IMP = inosine 5 -monophosphate AICAR = 5 -phosphoribosyl-5-amino-4-imida2olecarboxamide DAP = diaminopimelic acid PRPP = phosphoribosyl pyrophosphate a — KGA = a-ketoglutaric acid Orn = ornithine Cit = citnilline represents the one carbon unit lost to tetrahydrofolate as serine is converted to glycine. 

Fig. 1.2 A, peptidoglycan of Escherichia coli. , A -acetylmuramic acid , Af-acetylglucosamine. B, repeating unit of peptidoglycan ofE. coli. L-ala, L-alanine D-glu, D-glutamine DAP, diaminopimelic acid D-aia, D-alanine.

Cell walls of a number of Gram-positive and negative bacteria contain the amino acid diaminopimelic acid. 

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. 

When the biosynthetic pathways given above are examined, it is apparent that several intermediates are indeed nonprotein ct-amino acids. Ornithine, homoserine, homocysteine, and ct-e-diaminopimelic acid are a few examples. This shows that some nonprotein amino acids originate as intermediates during the biosynthesis of... 

The peptidoglycan structure of bacterial cell walls. The shaded areas represent points of attachment of this macromolecule to the rest of the cell wall. The amino sugar units are joined end to end to form long, straight chains. The peptides form cross-links when the amino group of a meso-diaminopimelic acid in one chain replaces the terminal alanine in another chain. Source ... 

The Grubbs method14 1 is readily applicable to the synthesis of other stereoisomers and can be expanded to include homologues with additional methylene units spanning the glycyl substructures. This method can also be applied to the stereoselective synthesis of selectively protected meso- or L,L-2,6-diaminopimelic acid and related differentially protected derivatives. [461... 

The fatty acid chains are evidently embedded in the outer membrane as an anchor. About one-third of the lipoprotein molecules are attached covalently to the peptidoglycan through an amide linkage between the side chain amino group of the C-terminal lysine of the protein and a diaminopimelic acid residue of the peptidoglycan (Fig. 8-29). Thus, the protein replaces one of the terminal D-alanine residues of about one in ten of the murein peptides. There are 2.5 x 105 molecules of the bound form of the lipoprotein per cell spread over a surface area of peptidoglycan of 3 pm2. They appear to be associated as trimers located primarily in the periplasmic space.589... 

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 ... 

Biological significance can sometimes arise in rather unexpected ways the thermal properties of chelate polymers of 2,6-diaminopimelic acid (dap 12) and 4,4 -diamino-3,3 -dicarboxybiphenyl (bbdc 13) with Zn11 have been compared241 with those of non-polymeric divalent metal chelates with amino acids. This confirms the expected enhancement of thermal stability when coordination polymerization occurs, these results possibly being relevant to the thermal stability of certain bacterial spores which contain dap. Zn11 complexes of dap are more thermally stable than those of bbdc, possibly because the latter chelate cannot pack as well, due to the intermolecular repulsions of the biphenyl groups. 

As expected easily from analogy with Lys, photocatalytic reaction in deaerated aqueous suspensions of semiconductor particles produces piperidine-2,6-dicarboxylic acid (PDC) from 2,6-diaminopimelic acid (DAP). The product PDC was optically inactive when an optically inactive 1 1 2 mixture of L, D, and meso isomers of DAP was used. However, two diastereomers, trans and cw-PDC s were obtained and their molar ratio strongly depended on the kind of photocatalyst used (Fig. 11.4). 

D, L-aspartic acid, y-aminobutyric acid, L-ornithine, L-lysine, glycylgly-cine, a-aminoadipic acid, diaminopimelic acid, and glutathione. 

In Gram-negative bacteria, as well as some Gram-positive strains, meso-diaminopimelic acid (meso-DAP) is incorporated in place of L-Lys. 

Figure 3 Schematic representation of the cytoplasmic steps of biosynthesis of UDP-N-acetylmuramic acid pentapeptide in E. coli. UDP-NAcGlc, UDP-N-acetylglucosamine PEP, phosphoenolpyruvate UDP-NAcEPGlc, UDP-N-acetylenolpyruvylglucosamine UDP-NAcMur, UDP-N-acetylmuramic acid meso-DAV, meso-diaminopimelic acid.

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