931. |
- Park, Hee-Sung, et al.
(författare)
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Design and evolution of new catalytic activity with an existing protein scaffold.
- 2006
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Ingår i: Science. - 1095-9203. ; 311:5760, s. 535-8
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Tidskriftsartikel (refereegranskat)abstract
- The design of enzymes with new functions and properties has long been a goal in protein engineering. Here, we report a strategy to change the catalytic activity of an existing protein scaffold. This was achieved by simultaneous incorporation and adjustment of functional elements through insertion, deletion, and substitution of several active site loops, followed by point mutations to fine-tune the activity. Using this approach, we were able to introduce beta-lactamase activity into the alphabeta/betaalpha metallohydrolase scaffold of glyoxalase II. The resulting enzyme, evMBL8 (evolved metallo beta-lactamase 8), completely lost its original activity and, instead, catalyzed the hydrolysis of cefotaxime with a (kcat/Km)app of 1.8 x 10(2) (mole/liter)(-1) second(-1), thus increasing resistance to Escherichia coli growth on cefotaxime by a factor of about 100.
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932. |
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933. |
- Poinar, HN, et al.
(författare)
-
Molecular coproscopy: Dung and diet of the extinct ground sloth Nothrotheriops shastensis
- 1998
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Ingår i: SCIENCE. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075. ; 281:5375, s. 402-406
-
Tidskriftsartikel (övrigt vetenskapligt)abstract
- DNA from excrements can be amplified by means of the polymerase chain reaction. However, this has not been possible with ancient feces. Cross-Links between reducing sugars and amino groups were shown to exist in a Pleistocene coprolite from Gypsum Cave, N
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934. |
- Ricci, R., et al.
(författare)
-
Requirement of JNK2 for scavenger receptor A-mediated foam cell formation in atherogenesis
- 2004
-
Ingår i: Science. - 1095-9203. ; 306:5701, s. 1558-61
-
Tidskriftsartikel (refereegranskat)abstract
- In vitro studies suggest a role for c-Jun N-terminal kinases (JNKs) in proatherogenic cellular processes. We show that atherosclerosis-prone ApoE-/- mice simultaneously lacking JNK2 (ApoE-/- JNK2-/- mice), but not ApoE-/- JNK1-/- mice, developed less atherosclerosis than do ApoE-/- mice. Pharmacological inhibition of JNK activity efficiently reduced plaque formation. Macrophages lacking JNK2 displayed suppressed foam cell formation caused by defective uptake and degradation of modified lipoproteins and showed increased amounts of the modified lipoprotein-binding and -internalizing scavenger receptor A (SR-A), whose phosphorylation was markedly decreased. Macrophage-restricted deletion of JNK2 was sufficient to decrease atherogenesis. Thus, JNK2-dependent phosphorylation of SR-A promotes uptake of lipids in macrophages, thereby regulating foam cell formation, a critical step in atherogenesis.
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935. |
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936. |
- Saxena, SK, et al.
(författare)
-
Detecting phases of iron
- 1997
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Ingår i: SCIENCE. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075. ; 275:5296, s. 94-96
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Tidskriftsartikel (övrigt vetenskapligt)
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937. |
- Saxena, SK, et al.
(författare)
-
Stability of perovskite (MgSiO3) in the Earth's mantle
- 1996
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Ingår i: SCIENCE. - 0036-8075. ; 274:5291, s. 1357-1359
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Tidskriftsartikel (refereegranskat)abstract
- Available thermodynamic data and seismic models favor perovskite (MgSiO3) as the stable phase in the mantle. MgSiO3 was heated at temperatures from 1900 to 3200 kelvin with a Nd-YAG laser in diamond-anvil cells to study the phase relations at pressures fr
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938. |
- SAXENA, SK, et al.
(författare)
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SYNCHROTRON X-RAY STUDY OF IRON AT HIGH-PRESSURE AND TEMPERATURE
- 1995
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Ingår i: SCIENCE. - : AMER ASSOC ADVAN SCIENCE. - 0036-8075. ; 269:5231, s. 1703-1704
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Tidskriftsartikel (övrigt vetenskapligt)abstract
- X-ray synchrotron experiments with in situ laser heating of iron in a diamond-anvil cell show that the high-pressure epsilon phase, a hexagonal close-packed (hcp) structure, transforms to another phase (possibly a polytype double-layer hcp) at a pressure
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939. |
- Scherer, RP, et al.
(författare)
-
Pleistocene collapse of the West Antarctic ice sheet
- 1998
-
Ingår i: SCIENCE. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075. ; 281:5373, s. 82-85
-
Tidskriftsartikel (refereegranskat)abstract
- Some glacial sediment samples recovered from beneath the West Antarctic ice sheet at ice stream B contain Quaternary diatoms and up to 10(8) atoms of beryllium-10 per gram. Other samples contain no Quaternary diatoms and only background levels of berylliu
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940. |
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