منابع مشابه
Caught in the act
Along with replication and mutability, living beings are set apart from the mineral background they inhabit by their metabolism—their ability to catalyse chemical reactions. Since Linus Pauling first proposed that these reactions are made pos sible by enzymes that recognize and bind tightly to their substrates at a crucial transi tion point [1], it has become increasingly clear that understan...
متن کاملCaught in the Act?
Galaxies are thought to be surrounded by massive halos of dark matter, each outweighing its galaxy by a factor of about eight. The visible part of a galaxy, occupying the inner 10% of the halo, consists of a mixture of stars and gas. Galaxies harbour a giant black hole at their centres, which in some cases is actively fuelled as it sucks in surrounding gas. In especially active galaxies, called...
متن کاملCaught in the act
The crystal structure of a HECT E3 enzyme has been captured as it transfers ubiquitin to a target protein, revealing the dramatic changes in shape that enable it to modify particular residues in its targets.
متن کاملEvolution: Organelles Caught in the Act
Mitochondria in the protist Brevimastigomonas motovehiculus are in the process of dismantling their mitochondrial electron transport chain complexes as they adapt to anaerobic environments. Novel protein interactions suggest a highly complicated process rather than the simple removal of unnecessary genes.
متن کاملHuman Telomerase Caught in the Act
Based on prior work, it was expected that telomerase would preferentially elongate the shortest telomeres in a cell, extending the telomeric G-rich strand through a process that is coupled to the synthesis of the complementary strand. Contrary to this view, Zhao et al. (2009) now show that telomerase in human cancer cells extends most telomeres during every S phase and that complementary strand...
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ژورنال
عنوان ژورنال: Science
سال: 2006
ISSN: 0036-8075,1095-9203
DOI: 10.1126/science.314.5796.19c