[[Image:Chloroquine 3D.png|thumb|upright=1.2|right|The biocrystallization inhibitor chloroquine was developed in Germany in the 1930s. For 20 years Chloroquine was a "magic bullet".]]
'''Biocrystallization''' is the formation of crystals from organic macromolecules by living organisms.<ref name="PMID 15625389">{{cite journal |author=Kachroo AH|title=Order in stress - lessons from the inanimate world|journal=Journal of Biosciences |volume=29 |issue=4 |pages=369–72 |date=December 2004 |pmid=15625389|url=http://www.ias.ac.in/jbiosci/dec2004/369.pdf |doi=10.1007/bf02712104|s2cid=13401792}}</ref> This may be a stress response, a normal part of metabolism such as processes that dispose of waste compounds, or a pathology. Template mediated crystallization is qualitatively different from ''in vitro'' crystallization. Inhibitors of biocrystallization are of interest in drug design efforts against lithiasis and against pathogens that feed on blood, since many of these organisms use this process to safely dispose of heme.
==DNA== {{biomineralization sidebar|general}}
Under severe stress conditions the bacteria ''Escherichia coli'' protects its DNA from damage by sequestering it within a crystalline structure.<ref name="pmid10403254">{{cite journal |vauthors=Wolf SG, Frenkiel D, Arad T, Finkel SE, Kolter R, Minsky A |title=DNA protection by stress-induced biocrystallization |journal=Nature |volume=400 |issue=6739 |pages=83–5 |date=July 1999 |pmid=10403254 |doi=10.1038/21918 |bibcode=1999Natur.400...83W|s2cid=204994265 }}</ref> This process is mediated by the stress response protein Dps and allows the bacteria to survive varied assaults such as oxidative stress, heat shock, ultraviolet light, gamma radiation and extremes of pH.<ref name="pmid15205421">{{cite journal |vauthors=Nair S, Finkel SE |title=Dps Protects Cells against Multiple Stresses during Stationary Phase |journal=J. Bacteriol. |volume=186 |issue=13 |pages=4192–8 |date=July 2004 |pmid=15205421 |doi=10.1128/JB.186.13.4192-4198.2004 |pmc=421617}}</ref><ref name=Frenkiel-krispin2002>{{cite journal | author = Frenkiel-Krispin, D. | author2 = Minsky, A. | year = 2002 | title = Biocrystallization: A last-resort survival strategy in bacteria | journal = ASM News | volume = 68 | issue = 6 | url = http://newsarchive.asm.org/jun02/feature2.asp | archive-url = https://web.archive.org/web/20110725021551/http://newsarchive.asm.org/jun02/feature2.asp | url-status = dead | archive-date = 2011-07-25 | access-date = 2008-05-05 }}</ref>
==Heme== Blood feeding organisms digest hemoglobin and release high quantities of free toxic heme. To avoid destruction by this molecule, the parasite biocrystallizes heme to form hemozoin.<ref>{{cite journal |vauthors=Hempelmann E, Marques HM |title=Analysis of malaria pigment from Plasmodium falciparum|journal=J Pharmacol Toxicol Methods |volume=32 |issue=1 |pages= 25–30|date=September 1994 |pmid=7833503 |doi= 10.1016/1056-8719(94)90013-2}}</ref> To date, the only definitively characterized product of hematin disposal is the pigment hemozoin. Hemozoin is ''per definitionem'' not a mineral and therefore not formed by biomineralization. Heme biocrystallization has been found in blood feeding organisms of great medical importance including ''Plasmodium'', ''Rhodnius'' and ''Schistosoma''. Heme biocrystallization is inhibited by quinoline antimalarials such as chloroquine.
Targeting heme biocrystallization remains one of the most promising avenues for antimalarial drug development because the drug target is highly specific to the malarial parasite, and outside the genetic control of the parasite.
==Lithiasis== Lithiasis (formation of stones) is a global human health problem. Stones can form in both urinary and gastrointestinal tracts. Related to the formation of stones is the formation of crystals; this can occur in joints (e.g. gout) and in the viscera.<ref>{{cite journal |vauthors=Porena M, Guiggi P, Micheli C |title=Prevention of stone disease|journal=Urol. Int.|volume= 79|pages= 37–46|year=2007 |pmid=17726351 |doi= 10.1159/000104440|s2cid=8068808}}</ref>
== See also == {{div col|colwidth=30em}}
* Biomineralization * Diatomaceous earth * Magnetotactic bacteria * Prion {{div col end}}
==References== {{reflist|colwidth=30em}}
==External links== * [http://www.ias.ac.in/jbiosci/dec2004/369.pdf Order in stress – Lessons from the inanimate world]
{{portal bar|Evolutionary biology|Geology|Paleontology}}
Category:Metabolism Category:Cell biology Category:Clinical chemistry Category:Biomineralization