Dipicolinic acid (pyridine-2,6-dicarboxylic acid or PDC and DPA) is a chemical compound which plays a role in the heat resistance of bacterial endospores. It is also used to prepare and transition metal complexes for ion chromatography.2,6-Pyridinedicarboxylic acid at Sigma-Aldrich
Biological role Dipicolinic acid composes 5% to 15% of the dry weight of Bacillus subtilis spores.Sci-Tech Dictionary. McGraw-Hill Dictionary of Scientific and Technical Terms, McGraw-Hill Companies, Inc. It has been implicated as responsible for the heat resistance of the endospore,Madigan, M., J Martinko, J. Parker (2003). Brock Biology of Microorganisms, 10th edition. Pearson Education, Inc., . although mutants resistant to heat but lacking dipicolinic acid have been isolated, suggesting other mechanisms contributing to heat resistance are at work.Prescott, L. (1993). Microbiology, Wm. C. Brown Publishers, . Two genera of bacterial pathogens are known to produce endospores: the aerobic Bacillus and anaerobic Clostridium.Gladwin, M. (2008). Clinical Microbiology Made Ridiculously Simple, MedMaster, Inc., .
Dipicolinic acid forms a complex with calcium ions within the endospore core. This complex binds free water molecules, causing dehydration of the spore. As a result, the heat resistance of macromolecules within the core increases. The calcium-dipicolinic acid complex also functions to protect DNA from heat denaturation by inserting itself between the nucleobases, thereby increasing the stability of DNA.Madigan. M, Martinko. J, Bender. K, Buckley. D, Stahl. D, (2014), Brock Biology of Microorganisms, 14th Edition, p. 78, Pearson Education Inc., .
Detection The high concentration of DPA in and specificity to bacterial endospores has long made it a prime target in analytical methods for the detection and measurement of bacterial endospores. A particularly important development in this area was the demonstration by Rosen et al. of an assay for DPA based on photoluminescence in the presence of terbium, although this phenomenon was first investigated for using DPA in an assay for terbium by Barela and Sherry.
Environmental behavior Simple substituted pyridines vary significantly in environmental fate characteristics, such as volatility, adsorption, and biodegradation. Dipicolinic acid is among the least volatile, least adsorbed by soil, and most rapidly degraded of the simple pyridines. A number of studies have confirmed dipicolinic acid is biodegradable in aerobic and anaerobic environments, which is consistent with the widespread occurrence of the compound in nature.Ratledge, Colin (ed). 2012. Biochemistry of microbial degradation. Springer Science and Business Media Dordrecht, Netherlands. 590 pages . With a high solubility (5g/liter) and limited sorption (estimated Koc = 1.86), utilization of dipicolinic acid as a growth substrate by microorganisms is not limited by bioavailability in nature.Anonymous. MSDS. pyridine-2-6-carboxylic-acid .Jubilant Organosys Limited. http://www.jubl.com/uploads/files/39msds_msds-pyridine-2-6-carboxylic-acid.pdf
See also Dinicotinic acid, an isomeric dicarboxylic acid 2,6-Pyridinedicarbothioic acid has both -COOH (carboxylic acid) groups replaced by -COSH (thiocarboxylic acid) groups
References
External links at JPL. at Astrobiology Magazine.