Figure 3.

Structure of the E. coli biotin carboxylase in complex with ATP. A stereo-view of one subunit of the enzyme is presented in (a). The color-coding is the same as in Figure 2. The bound ATP is depicted in sphere representation. Note how the B-domain closes down upon nucleotide binding. Those amino acid residues important for ATP binding are shown in (b). The structure shown is that of the E288K mutant protein. Potential hydrogen bonds are indicated by the dashed lines. X-ray coordinates were obtained from the Protein Data Bank (1DV2).