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Protein Shows Conformational Fluctuations at Cryogenic Temperatures
Proteins must fluctuate in order to perform cellular functions, such as enzymatic catalysis, protein-protein interactions, and interactions with DNA and RNA. When proteins are cooled the fluctuations dampen and eventually stop, typically at 200 - 240 K. This is called a protein dynamical transition. Proteins below the transition temperature show no appreciable biological function. Above the transition temperature flexibility is restored and the protein becomes increasingly biologically active.
Full article here: http://news.chess.cornell.edu/articles/2012/ProCryo01112012.html
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The Ring of Life: X-ray Scattering Reveals Secrets Leading to DNA Synthesis
Synthesis of DNA is an essential foundation for all life on Earth. In all organisms, the precursors for DNA (deoxyribonucleotides) are made from the precursors for RNA (ribonucleotides) using an enzyme called ribonucleotide reductase (RNR). RNRs are classified by the metal-containing cofactor that is used to generate a radical essential for catalysis. Class Ia RNRs (used by all eukaryotes and many aerobic bacteria) are unusual in that the nucleotide-binding sites and the radical-generating metallocofactor are housed in separate homodimeric proteins.
Full article here: http://news.chess.cornell.edu/articles/2012/ROL01062012.html