For the cryoprotective
solvent, glycerol (49770, purchased from Honeywell) was mixed with
MilliQ water to obtain a glycerol concentration of 23 mol % (corresponding
to 55 vol % or 60 wt %). Lysozyme from hen egg white (14.3 kDa) was
purchased from Sigma-Aldrich (L6876) and was used without further
purification. The protein powder was dissolved in the 23 mol % glycerol–water
solution with protein concentrations of 10 and 200 mg/mL. The resulting
pH of the protein solutions was measured to be 4.1 ± 0.1 at room
temperature, similar to the pH range used in previous studies of lysozyme
in glycerol–water mixtures.31 (link)−34 (link) Since lysozyme is known to exhibit
a maximum thermal stability at pH ≈ 5, while high pH values
promote the aggregation of unfolded lysozyme,35 (link),36 (link) no additional salt was added to the system. The resulting solutions
were filled in quartz capillaries of 1.5 mm in diameter for X-ray
scattering studies.
solvent, glycerol (49770, purchased from Honeywell) was mixed with
MilliQ water to obtain a glycerol concentration of 23 mol % (corresponding
to 55 vol % or 60 wt %). Lysozyme from hen egg white (14.3 kDa) was
purchased from Sigma-Aldrich (L6876) and was used without further
purification. The protein powder was dissolved in the 23 mol % glycerol–water
solution with protein concentrations of 10 and 200 mg/mL. The resulting
pH of the protein solutions was measured to be 4.1 ± 0.1 at room
temperature, similar to the pH range used in previous studies of lysozyme
in glycerol–water mixtures.31 (link)−34 (link) Since lysozyme is known to exhibit
a maximum thermal stability at pH ≈ 5, while high pH values
promote the aggregation of unfolded lysozyme,35 (link),36 (link) no additional salt was added to the system. The resulting solutions
were filled in quartz capillaries of 1.5 mm in diameter for X-ray
scattering studies.
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