The spectral shape of the synchrotron X-ray emission from SN 1006 reveals the fundamental role played by radiative losses in shaping the high-energy tail of the electron spectrum .
We analyze data from the XMM-Newton SN 1006 Large Program and confirm that in both nonthermal limbs the loss-limited model correctly describes the observed spectra .
We study the physical origin of the observed variations of the synchrotron cutoff energy across the shell .
We investigate the role played by the shock velocity and by the electron gyrofactor .
We found that the cutoff energy of the syncrotron X-ray emission reaches its maximum value in regions where the shock has experienced its highest average speed .
This result is consistent with the loss-limited framework .
We also find that the electron acceleration in both nonthermal limbs of SN 1006 proceeds close to the Bohm diffusion limit , the gyrofactor being in the range \eta \sim 1.5 - 4 .
We finally investigate possible explanations for the low values of cutoff energy measured in thermal limbs .