“…However, important details regarding kinetics and specificity of the proofreading exonuclease are lacking. Other groups have reported expression, purification, and preliminary activity assays for the SARS-CoV-2 exonuclease complex. ,− ,, From these studies, it is clear that the exonuclease activity of NSP14 (1) requires either Mg 2+ or Mn 2+ for catalysis ,,, (2) strongly prefers RNA bases over DNA bases, , and (3) is greatly stimulated by the addition of the noncatalytic NSP10 . However, there are contradictions in the literature as to whether a remdesivir incorporated into the primer strand of the RNA can be efficiently excised by the exonuclease complex ,, and whether the enzyme preferentially hydrolyzes single-stranded RNA over base-paired RNA or RNA with terminal mismatches. ,,,, …”