Table 2.
ATP hydrolysis rates of the isoforms
| Isoform | Hsp82 | Hsc82 |
| ATPase (kcat (min−1)) at 30 °C | 0.52 ± 0.02 | 0.65 ± 0.02 |
| with Aha1 | 11.59 ± 1.05 (≙2229%) | 18.63 ± 0.48 (≙2866%) |
| with Cpr6 | 1.42 ± 0.07 (≙273%) | 1.81 ± 0.08 (≙278%) |
| with Cdc37 | 0.24 ± 0.02 (≙46%) | 0.37 ± 0.09 (≙57%) |
| with Sba1 | 0.38 ± 0.01 (≙73%) | 0.57 ± 0.03 (≙88%) |
| with Sti1 | 0.06 ± 0.01 (≙12%) | 0.06 ± 0.02 (≙9%) |
| ATPase (kcat (min−1) at 37 °C | 1.37 ± 0.02 | 2.13 ± 0.13 |
| Isoform | 6His-Hsp82 | 6His-Hsc82 |
| ATPase (kcat (min−1)) at 30 °C | 0.75 ± 0.06 | 1.23 ± 0.10 |
| Isoform domain | Hsp82NTD | Hsc82NTD |
| Affinity for ATP (Kd (µM)) | 88 ± 14 | 151 ± 33 |
| Affinity for RD (Kd (nM)) | 2.7 ± 1.6 | 2.0 ± 0.8 |
The ATPase activities of Hsp82 and Hsc82 were measured with an ATP-regenerating system23. The influence of temperature (30 °C versus 37 °C), of 6His-tagging, and of co-chaperones on the ATPases are shown. In addition, affinities for ATP and RD were determined by ITC and Kd values are indicated.