Enzyme | SK | AK1A | AK1B |
---|
Residue | Interatomic distance (Å) | Residue | Interatomic distance (Å) | Residue | Interatomic distance (Å) |
---|
1. C8-H to α-PO4 | | 3.666 | | 4.153 | | 3.729 |
2. αC = O to C6-NH2 | R153 | 1.893 | G177 | 1.880 | NR1 | |
3. Thr-OH to C8H | T17 | 3.273 | T23 | 2.090 | T392 | 1.786 |
4. Thr-OH to α-PO4 | T17 | 1.758 | T23 | 2.591 | T39 | 5.648 |
5. Arg-NH1 to C8 | R110 | 4.228 | R128 | 4.781 | R972 | 2.712 |
6. Arg-α-PO4 | R117 | 2.757 | R132 | 2.136 | R44 | 1.904 |
7. Lys- γ-PO4 | K15 | 1.882 | K21 | 1.902 | K21 | 1.865 |
- NR = No coordinated residue.
- Coordinated to N7.
- The amino acid residues making up the “push” mechanism within the active sites of SK and AK1 identified by the inter-atomic distances between the co-crystallized nucleotide analogue and the amino acid residues within the active site. These residues included: the Thr associated with the proton transfer from C8-H to the α-PO4 (SK, Thr17; AK1, Thr 23), the Arg associated with C8 protonation (SK, Arg110; AK1, Arg128), the Arg co-ordinated to the α-PO4 and β-PO4 (SK, Arg117; AK1, Arg132), and the Lys associated with the γ-PO4 protonation (SK, Lys15; AK1, Lys21). The residues identified in the AK1 second nucleotide binding site (AK1B) are: Thr39 (associated with the proton transfer from C8-H to the α-PO4), Arg97 (associated with C8 protonation), Arg44/138 (co-ordinated to the α-PO4 and β-PO4), and Lys21 (associated with the γ-PO4 protonation).