Corrections binding

Generally, between the two halves of the palindrome (or of the direct repetition) there are from one to five nucleotide spacers whose sequence varies from one gene to another. The sequence in which these nucleotides are found is irrelevant, as they do not directly participate in the dimer-DNA interaction. It is very important, however, that the number of nucleotide spacers be fixed to allow for correct binding to its corresponding receptor dimer. 

All geometrical optimizations were performed with the keywords tight and Int=UltraFine . The unsealed harmonic vibrational frequencies, zero-point vibrational energies (ZPVE), and enthalpies were also calculated. The ZPVE-corrected binding energies E , are reported throughout the work. 

Nitrogenase catalyzes the reduction of a number of substrates in addition to N2 and H+. Acetylene is reduced to ethylene, and nitrous oxide to dinitrogen, while azide undergoes reduction to N2 and NH3. In the last two cases the product N2 is not reduced further, implying that it is not in the correct binding position for reduction. The presence of multiple sites on the MoFe protein suggested by this observation is also supported by the non-competitive nature of the inhibition shown by some of these compounds. The reduction of acetylene has been used as a marker reaction for nitrogenase activity. 

In addition to its role at the active sites of hundreds of enzymes, there are cases where zinc serves a purely structural role. The most notable of these are the zinc fingers and some related twists and clusters. These occur in DNA binding proteins where they stabilize the correct binding sites. Figure 15-7 shows... 

Cc to the correct binding site during the final stages of the complex formation process (Figure 15). 

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