Tunnel vision
Article Abstract:
An explanation has been put forward for why the catalytic activity of thermophilic enzymes is low or absent at moderate temperatures at which ordinary enzymes of similar function are optimally active. This explanation focuses on a fall in thermophilic enzyme flexibility at mesophilic temperatures. It was established that the kinetic isotope effect is almost independent of temperature between 65 degrees C and 30 degrees C. At below 30 degrees C, the kinetic isotope effect shows a steep slope, suggesting that at around room temperature a dynamical transition takes place that hinders hydrogen tunneling.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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Heavy metal revival
Article Abstract:
The cytotoxic effects of cisplatin, an inorganic compound widely used as an anticancer drug, arise from the covalent binding to DNA. The complex formed by the binding of the cis form of cisplatin to DNA allows changes in the structure of the complex that are necessary for the binding of high-mobility-groups (HMG) to the complex. The binding of HMG to the cisplatin-DNA complex prevents repair of the DNA in tumor cells. The complex formed by the trans isomer does not allow these structural changes. This may be the reason why the trans isomer does not have any anti-cancer properties.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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Design by necessity
Article Abstract:
A combination of design and necessity can quickly evolve one enzyme in a biosynthetic pathway into another, according to research designed to convert indole glycerol phosphate synthase into phosphoribosyl anthranilate isomerase (PRAI). It was established that converting one triosephosphate isomerase-barrel enzyme into another by altering the loop regions leads to a different solution to the problem of catalyzing the PRAI reaction. This research provides a possible model for the natural evolution of new enzyme activities from an existing scaffold.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2000
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