In the new coronavirus (SARS-CoV-2), viruses with D614G mutation in S proteins are now the mainstream of infection. A group of University of Massachusetts Medical School et al. has reported their findings on the causes of why D614G mutation is to be more infectious than the past D614.
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Using SPR, the experimental results of the interaction between D614G and ACE2 indicate that it is not due to increased affinity of D614G mutation to ACE2 (rather, slightly affinity is lowered), Structural analysis of S proteins by cryo-EM shows that the presence rates of Close and Open status in RBD (Receptor Binding Domain) have changed, and that D614G mutation is more likely to have Open structures than D614. Therefore, it has been concluded that the increased infectivity of D614G is due to the more exposed RBD of the S protein.