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| '''Franz Hofmeister''' (1850–1922) was an early protein scientist, and is famous for his studies of salts that influence the solubility and conformational stability of [[protein]]s. Hofmeister was the first to propose that polypeptides were [[amino acid]]s linked by [[peptide bond]]s in 1902, although this model of protein [[primary structure]] was independently and simultaneously conceived by [[Hermann Emil Fischer|Emil Fischer]].
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| ==Early life==
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| Hofmeister's father was a doctor in Prague, where Hofmeister first began his studies, under the physiologist [[Karl Hugo Huppert]], himself a student of Carl Lehmann. Hofmeister's ''Habilitationsschrift'' in 1879 concerned the peptic products of digestion.
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| Hofmeister became professor of Pharmacology in [[Karl-Ferdinands-Universität|Prague]] in 1885, then moved to Strasbourg in 1896.
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| ==The Hofmeister series==
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| {{main|Hofmeister series}}
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| Hofmeister discovered a series of salts that have consistent effects on the solubility of proteins and (it was discovered later) on the stability of their [[secondary structure|secondary]] and [[tertiary structure]]. Anions appear to have a larger effect than cations, and are usually ordered
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| :<math>
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| \mathrm{F^{-} \approx SO_{4}^{2-} > HPO_{4}^{2-} > acetate > Cl^{-} > NO_{3}^{-} > Br^{-} > ClO_{3}^{-} > I^{-} > ClO_{4}^{-} > SCN^{-}}
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| </math>
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| (This is a partial listing; many more salts have been studied.)
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| The order of cations is usually given as
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| :<math>
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| \mathrm{NH_{4}^{+} > K^{+} > Na^{+} > Li^{+} > Mg^{2+} > Ca^{2+} > guanidinium}
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| </math>
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| The mechanism of the Hofmeister series is not entirely clear, but seems to result mainly from effects on the solvent at higher salt concentrations (> 100 mM). Early members of the series increase solvent surface tension and decrease the solubility of nonpolar molecules (''salt out''); in effect, they ''strengthen'' the [[hydrophobic interaction]]. By contrast, later salts in the series increase the solubility of nonpolar molecules (''salt in'') and decrease the order in water; in effect, they ''weaken'' the [[hydrophobic effect]]. However, these salts also interact directly with proteins (which are charged and have strong dipole moments) and may even bind specifically (e.g., phosphate and sulfate binding to [[ribonuclease A]]). Ions that have a strong ''[[salting in]]'' effect such as I<sup>−</sup> and SCN<sup>−</sup> are strong denaturants, because they salt in the peptide group, and thus interact much more strongly with the unfolded form of a protein than with its native form. Consequently, they ''pull'' the unfolding reaction.<ref name="baldwin">{{cite journal |author=Baldwin RL. |title=How Hofmeister ion interactions affect protein stability |journal=Biophys J |volume=71 |issue=4 |pages=2056–63 |year=1996 |pmid=8889180 |doi=10.1016/S0006-3495(96)79404-3 |pmc=1233672 |bibcode=1996BpJ....71.2056B}}</ref> Moreover, they may have direct interactions with some standard hydrophobic molecules, e.g., [[benzene]].
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| ==Protein purification==
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| The importance of the Hofmeister series to early protein work cannot be underestimated, since it provided the chief tool for purifying proteins (sulfate precipitation) over the next ~50 years, one that is still in use today. Hofmeister himself may have been the first to crystallize a protein, hen egg-white albumin. Repeated crystallization was a favorite purification technique in the early days of protein science, and was essential for its development.
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| ==Proposal of protein primary structure==
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| Hofmeister argued for peptide bonds by process of elimination. C-C, ether and ester bonds were unlikely considering the digestion by [[trypsin]]. R=C-N-C=R bonds could be eliminated because it would imply a much larger number of [[carboxylate]] groups than is observed experimentally.
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| Hofmeister also argued for peptide bonds based on the [[biuret reaction]] observed with all proteins but never with free amino acids. Since [[biuret]] has the formula NH<sub>2</sub>-CO-NH-CO-NH<sub>2</sub>, that suggested the presence of similar peptide bonds in proteins.
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| ==See also==
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| * [[primary structure]]
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| * [[peptide bond]]
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| * [http://www.scienceandsociety.co.uk/results.asp?image=10323274 Picture of Hofmeister at Science and Society site, UK]
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| * [http://www.cendigital.org/cendigital/20120716?sub_id=FNQ5wyPIC7Sq&folio=42#pg46 Hofmeister Still Mystifies, ''Chemical & Engineering News'', July 16, 2012.]
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| ==References==
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| <references/>
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| * Hofmeister F. (1888) ''Arch. Exptl. Pathol. Pharmakol.'', '''24''', 247.
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| *{{cite journal | pmid = 17035073 | doi=10.1016/j.cbpa.2006.09.020 | volume=10 | issue=6 | title=Interactions between macromolecules and ions: The Hofmeister series |date=December 2006 | pages=658–63 | last1 = Zhang | first1 = Y | last2 = Cremer | first2 = P | journal = Current Opinion in Chemical Biology}}
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| *{{cite journal | pmid = 16044460 | doi=10.1002/prot.20500 | volume=61 | issue=1 | title=Interactions of macromolecules with salt ions: an electrostatic theory for the Hofmeister effect |date=October 2005 | pages=69–78 | last1 = Zhou | first1 = Huan-Xiang | journal = Proteins: Structure, Function, and Bioinformatics}}
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| * Tanford C and Reynolds J. (2001) ''Nature's robots: a history of proteins'', Oxford University Press. ISBN 0-19-850466-7
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| * Creighton TE. (1993) ''Proteins'', 2nd ed., W. H. Freeman. ISBN 0-7167-2317-4
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| * Jencks WP. (1969) ''Catalysis in Chemistry and Enzymology'', Dover republication (1987). ISBN 0-486-65460-5
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| * {{cite journal | last1 = Collins | first1 = KD. | last2 = Washabaugh | first2 = MW. | year = 1985 | title = The Hofmeister effect and the behaviour of water at interfaces | url = | journal = Q Rev Biophys | volume = 18 | issue = 4| pmid = 3916340 | pages = 323–422 }}
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| {{See also|Hofmeister (disambiguation){{!}}Hofmeister}}
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| {{Persondata <!-- Metadata: see [[Wikipedia:Persondata]]. -->
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| | NAME = Hofmeister, Franz
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| | ALTERNATIVE NAMES =
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| | SHORT DESCRIPTION = German scientist
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| | DATE OF BIRTH = 1850
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| | PLACE OF BIRTH = [[Prague]]
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| | DATE OF DEATH = 1922
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| | PLACE OF DEATH =
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| }}
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| {{DEFAULTSORT:Hofmeister, Franz}}
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| [[Category:1850 births]]
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| [[Category:1922 deaths]]
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| [[Category:19th-century German people]]
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| [[Category:20th-century German people]]
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| [[Category:19th-century Czech people]]
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| [[Category:19th-century chemists]]
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| [[Category:20th-century chemists]]
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| [[Category:German chemists]]
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| [[Category:Czech chemists]]
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| [[Category:German biochemists]]
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| [[Category:German people of German Bohemian descent]]
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| [[Category:German Bohemian people]]
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| [[Category:People from Prague]]
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