Domain Swapped Model of an RNase Fibril
10Q Insert
after residue N113
Summary: The C-terminal strand is domain swapped along the length of the fibril.
The swapping is "run-away" not "closed."
Each successive strand in the spine is translated
by 4.88 Angstroms and rotated by -7 degrees.
The pitch is 360.0*4.88/7=251 Angstroms.
The average radius is 132 Angstroms.
Current view: Each subunit is color ramped from blue to red, Nterm to Cterm.
The 10Q insert is red (near C-term).
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1) Two antiparallel beta sheets comprise
the spine of the fiber.
One of the sheets comprises purple and violet RNase molecules,
the other sheet comprises yellow and cream molecules.
The two sheets are approximately 9 Angstroms apart.
2) The glutamine side chains are shown in green.
They are capable
of hydrogen bonding along
the fiber axis, within a single sheet, not between sheets. The sheets are held
together by Van der Waals forces, using the NNQQNY crystal structure as a template.
3) The asymmetric unit of the fibril is composed of four RNase molecules, shown here in
purple and violet.
Purple swaps with violet along the length of the fibril. These molecules belong to a single sheet.
The second sheet, containing yellow and cream molecules,
can be generated by a 2-fold rotation operation around the fibril axis.
There is no swapping between sheets.
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