Extremophile
From Proteopedia
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== Negative surface charge and solubility == | == Negative surface charge and solubility == | ||
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In salty water, most proteins aggregate. That proteins on the outside of some archea in the dead sea manage to remain soluble in solutions entering up to one salt molecule for every two H20 molecules is quite stunning. Over a decade's work, Joel SUssman, Ada Zamir, and others at Weizmann Institute and Tel Aviv University have shown that the negative density on the surface of proteins turn them into anion-like, hence soluble in salt-containing solutions. The more recent research involved halotolerant organisms's halotolerant enzymes, and showing that their intermediate negative surface charge enables them to walk the tightrope between little salt and salf-saturating conditions, repectively. Still mysterious, though, is why all halophilic proteins aren't for the same price halotolerant - what use is all that extra negative surface charge? | In salty water, most proteins aggregate. That proteins on the outside of some archea in the dead sea manage to remain soluble in solutions entering up to one salt molecule for every two H20 molecules is quite stunning. Over a decade's work, Joel SUssman, Ada Zamir, and others at Weizmann Institute and Tel Aviv University have shown that the negative density on the surface of proteins turn them into anion-like, hence soluble in salt-containing solutions. The more recent research involved halotolerant organisms's halotolerant enzymes, and showing that their intermediate negative surface charge enables them to walk the tightrope between little salt and salf-saturating conditions, repectively. Still mysterious, though, is why all halophilic proteins aren't for the same price halotolerant - what use is all that extra negative surface charge? | ||
Revision as of 23:24, 20 March 2013
Contents |
Extraordinary Proteins
Where there is no man, be a bacteria
Where no man or plant could survive, bacteria have been eking out a living, and some even thriving. From the Dead Sea which has 10 times the concentration of salt in salt sea water to the hot springs heated by the molten center of the earth, that pour forth through vents deep under the sea (see this fantastic Thermophile Video from BBC Wildlife) - in all these hostile environments, life has found footing. To make the question stronger, realize that many things can go wrong, cells could burst or shrivel, DNA can become undone and tattered, protein can unfold into a jumbled mass of amino acids, and membranes made of fat molecules can rip and melt. Environment stress usually achieves all or many of these deadly process to organisms - yet some bacteria survive. To study how the extremophiles (extreme-loving bacteria) survive involves explaining how each of the above processes that should kill the bacteria, in fact do not occur. To understand all of these is a tall order, but to start, in this Proteopedia article, we'll tackle the protein survival under extreme stress problem.
Extremophiles talk in thermodynamics terms
All stresses must be interpreted into the language of thermodynamics, since that is the most faithful representation of the problems the environment brings to proteins, and the way the structures have solved this problem, and found a way to maintain their stability.
The principle equation is:
- ∆G = ∆H - T∆S.
- ∆G = ∆H - T∆S.
Where ∆G is negative, the movement to products in the reaction is spontaneous. This means, for the case of going from unfolded protein to folded protein as the product, a negative ∆G wold correspond to a stable protein structure. The other three terms: ∆H, T, and ∆S correspond to the change in enthalpy, the temperature (in Kalvins), and the change in entropy. Where the product is more stable than the reactants, ∆H will be negative, and the products are more ordered than the reactant, ∆S will be negative. It can be seen from the equation that ∆G becomes more negative for a more negative ∆H or for a less negative ∆S.
Negative surface charge and solubility
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Proline in Entropy and between-chain ion-network bonding
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Proteopedia Page Contributors and Editors (what is this?)
Joseph M. Steinberger, Joel L. Sussman, Alexander Berchansky, Michal Harel
