  On 2018-01-17 two electron crystallography structures (with PDB entries 6AXZ,
6BTK) on a prion protofibril of bank vole PrP(168-176) (a segment in the PrP
$\beta$2-$\alpha$2 loop) were released into the PDB Bank. The paper published
by [Nat Struct Mol Biol 25(2):131-134 (2018)] reports some polar clasps for
these two crystal structures, and "an intersheet hydrogen bond between Tyr169
and the backbone carbonyl of Asn171 on an opposing strand." - this hydrogen
bond is not between the neighbouring Chain B and Chain A directly. In addition,
by revisiting the polar clasps, we found another two hydrogen bonds
(B.Asn171@H-A.Gln172@OE1, B.Tyr169@OH-A.Gln172@N) between the strand A of one
sheet and the opposing strand B of the mating sheet. For the neighbouring two
single $\beta$-sheets AB, the two new hydrogen bonds are completely different
from the experimental one (an intersheet hydrogen bond between Tyr169 and the
backbone carbonyl of Asn171 on an opposing strand) in [Nat Struct Mol Biol
25(2):131-134 (2018)].
