In all living organisms, molecules are transformed into new chemical substances through processes which are catalysed by enzymes. Enzymes are proteins whose catalysing capacity enables chemical reactions which otherwise would not occur with sufficient speed or in a controlled way. The molecular evolution of enzymes is based on major or minor structural changes in a protein, which acquires new catalytic characteristics through the modification. The mutations in the genetic material which cause these structural changes have been regarded as random, but in certain cases it appears as if certain positions in a protein mutate more frequently than other positions in the protein. These positions are assumed to be particularly important to the biological functions of the protein.
Glutathione transferases are a family of enzymes which catalyse the detoxification of a broad spectrum of mutagens and carcinogens. Through major or minor structural variations, these enzymes have acquired new characteristics, thereby giving rise to more detoxification enzymes and a reinforced defence against toxic substances. A team of researchers led by Professor Bengt Mannervik has now shown that mutations in a single position in a glutathione transferase can dramatically alter the enzyme’s capacity to act selectively on various toxic substances. Through one type of mutation, the enzyme will become adapted to reactions in which the reactive group in the toxic substance is split off and replaced by glutathione, the body’s protective substance; through alternative mutations, the enzyme acquires the capacity to neutralise other reactive groups by linking them with glutathione.
“This discovery shows how the evolution of new enzyme functions may be quickly adapted to new needs. This is particularly significant for the defence against new toxins which may appear and threaten the survival of biological organisms,” says Bengt Mannervik.
This new study complements an earlier study by the research team, published in Science in January, which showed how a protein could be tailored to fulfil new functions through major changes to its structure.
Anneli Waara | alfa
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At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
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Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
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Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
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