Anatomy of the ATP-RyR interaction: distribution energy calculated from the experimental EC50 and the maximum increase inP o
| Compound | ΔG | |
|---|---|---|
| Po | EC50 | |
| cal/mol | ||
| Adenine-ribose-O-P-O-P-O-P-O | 3451 (3459) | 4952 (4956) |
| Adenine-ribose-O-P-O-P-O | 2115 | 3952 |
| Adenine-ribose-O-P-O O-P-O | 2399 | 4629 |
| Adenine-ribose-O O-P-O-P-O | 3226 | 5179 |
| Adenine O-P-O-P-O-P-O | 3869 | 4879 |
| ribose-O-P-O-P-O-P-O | 3352 | 4988 |
The imaginary compounds are indicated by the missing parts of the linear formula. The first row is the complete ATP molecule. Row two contains an imaginary molecule obtained by omitting the terminal (γ ) PO3; the atoms remaining have exactly the same position and charge as in ATP. Row 2 is similar, but not identical to, the ADP used in the experimental data. Row 3 is obtained from ATP (row 1) by removal of the β PO2 group. This is similar (but not identical) to an AMP plus a phosphate. In row 4, the α PO2 group is removed. This is similar to an adenosine plus a pyrophosphate. In row 5, the ribose is omitted. In row 6, the adenine base is omitted. The values in columns 2 and 3 are calculated with the indicated atoms missing while the remaining atoms retain the charge, position, and other properties found in ATP. The experimentally determined values are shown in parentheses for comparison with the predicted values of ATP.