The 1AGP crystal structure was solved with a GTP-like molecule called GNP bound in the active site.
If the wild type human KRas2 has a glycine at position 12, how would these non-covalent interactions be affected? Would you predict an increase in GTP binding or a decrease in GTP binding in the wild type KRas2 compared with the protein shown here? If there was a cysteine present at position 12, would this be more similar to Asp (H-bonding) or Gly (no H-bond)? Please explain by drawing a picture of the noncovalent interaction between the cysteine side chain and the terminal phosphate. Would you predict that the amino acid at position 12 would have an effect on GDP binding? Why or why not? Do you predict that the G12C mutation leads to a more active,less active, or unchanged form of Ras? Please explain your reasoning.