A,/?-diaminopimelic acid

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... 

It should also be mentioned that glycopeptides closely related to the pep-tido-polysaccharide of human-strain, wax D fractions are found in the culture filtrate of tubercle bacilli and in aqueous extracts thus, Kdra and Keil have described a glycopeptide, isolated from culture filtrates of virulent, human strains of M. tubercidosia, which could be purified by preparative electrophoresis and which contains alanine, a, -diaminopimelic acid, and glutamic acid in equimolecular proportions structure (22) was proposed for the peptide portion of this glycopeptide. 

Freund and Lipton have shown that an Actinomycete, Nocardia as-teroides, has the same adjuvant action as Mycobacteria. The cell wall of this organism has a structure very similar to that of Mycobacteria—alanine, glutamic acid, a, -diaminopimelic acid, arabinose, mannose, and galactose being the principal components. White has shown that the wax D of Nocardia asteroidea is inactive as an adjuvant, whereas the delipidated cells are active. 

The spectrum of the meso form of a, -diaminopimelic acid displays some sharp bands from 1667 to 1250 cm . The L form has a more diffuse spectrum in this region. Between 1250 and 667 cm" there is no resemblance between the spectra. 

Diethyl a, -dibromopimelate refluxed 15 hrs. with activated Na-azide in abs. ethanol, the crude product dissolved in abs. benzene, treated dropwise with a soln. of triphenylphosphine in benzene, refluxed 5 hrs., the solvent removed in vacuo, and the residue refluxed 5 hrs. with a 1 1 mixture of 40%-HBr and acetic acid -> a, -diaminopimelic acid. Y ca. 100%. F. e. s. F. Lingens, Z. Naturf. 15b, 811 (1960). 

D,L-a, -diaminopimelic acid No Rf values Methanol-water-pyridine, 77 20 10 Paper No. 1, Whatman, USA Development time 26 h Visualization ninhydrin 63 1955 ... 

In organisms containing diaminopimelic acid both the meso- and the LL-forms (189) occur. The interconversion of the two forms can now be explained by the finding of a diaminopimelic acid racemase (190). The presence of the racemase strengthens the conclusion that diaminopimelic decarboxylase is specific for the meso compound. 

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 ... 

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 ... 

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

Irradiation of 2,6-diaminopimelic acid in a CdS suspension gave trans-2,6-piperidinedicarboxylic acid, as a pair of enantiomers, along with the single c/s-diastereomer (Scheme 26) <95TL(36)3189>. 

A substantial number of PLP enzymes catalyze the racemization or epimerization of primary a-amino acids [54,55]. Of particular physiological importance are microbial alanine racemases because of their involvement in bacterial cell wall formation, which makes them a potential target for chemotherapy. An interesting substrate specificity is exhibited by diaminopimelate racemase [56] which acts only on meso-and LL-diaminopimelate, but not on the DD-isomer, i.e., the enzyme requires the L configuration at one end of the molecule in order to epimerize the chiral center at the other end. Racemization is also occasionally observed as an alternate catalytic... 

The overall fold of MIPS is similar to that of diaminopimelic acid dehydrogenase from Corynebacterium glutamicum and dihydrodipicolinate reductase from E. coli. Though the reactions catalyzed by these enzymes are quite different, they all use either NAD+ or NADP+ bound to a structurally similar Rossmann fold domain, and all three contain a (3 sheet domain located underneath the Rossmann fold and directly beneath the nicotinamide moiety that defines part of the active site (Norman et al., 2002 Stein and Geiger, 2002). 

The oomycetes, hyphochytrids, labyrinthuloids, and thraustochytrids are included in the kingdom Heterokontobionta or pseudofungi [54] based on the presence of cellulose in their cell walls, a tubular mitochondrial crista, hetero-kont flagella, one decorated with tripartite hairs, and the a, (3-diaminopimelic acid lysine biosynthetic pathway. The slime molds were classified into the kingdom Protozoa [38]. 

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