Halophilic enzymes: proteins with a grain of salt
Halophilic enzymes, while performing identical enzymatic functions as their non-halophilic counterparts, have been shown to exhibit substantially different properties, among them the requirement for high salt concentrations, in the 1–4 M range, for activity and stability, and a high excess of acidic...
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Published in | Biophysical chemistry Vol. 86; no. 2; pp. 155 - 164 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Netherlands
Elsevier B.V
30.08.2000
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Subjects | |
Online Access | Get full text |
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Summary: | Halophilic enzymes, while performing identical enzymatic functions as their non-halophilic counterparts, have been shown to exhibit substantially different properties, among them the requirement for high salt concentrations, in the 1–4 M range, for activity and stability, and a high excess of acidic over basic amino residues. The following communication reviews the functional and structural properties of two proteins isolated from the extremely halophilic archaeon
Haloarcula marismortui: the enzyme malate-dehydrogenase (hMDH) and the 2Fe–2S protein ferredoxin. It is argued that the high negative surface charge of halophilic proteins makes them more soluble and renders them more flexible at high salt concentrations, conditions under which non-halophilic proteins tend to aggregate and become rigid. This high surface charge is neutralized mainly by tightly bound water dipoles. The requirement of high salt concentration for the stabilization of halophilic enzymes, on the other hand, is due to a low affinity binding of the salt to specific sites on the surface of the folded polypeptide, thus stabilizing the active conformation of the protein. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-3 content type line 23 ObjectType-Review-1 |
ISSN: | 0301-4622 1873-4200 |
DOI: | 10.1016/S0301-4622(00)00126-5 |