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BitSpawn's AFP from puzzle 1095.

75: Antifreeze Protein is a revisiting puzzle, originally presented in 2008 as Puzzle 75: Antifreeze Protein.

The protein in this puzzle is an antifreeze protein (AFP), which cold water fishes use to keep from freezing. This protein is from a type of fish known as an eelpout, specifically an ocean pout, Zoarces americanus.

The same protein also appears in the Ice Binding series of revisiting puzzles.

The antifreeze AFPs are not be confused with alpha-fetoprotein, also known as AFP.

The puzzle has 66 segments with the sequence:


This sequence is found in the following Protein Data Bank entry:

  • 1B7I (chain A, offset 0)

There are also other PDB entries which match 65 out of 66 segments:

  • 1AME (chain A, offset 1)
  • 5C7R (chains A and B, offset 370)

In 1AME and 5C7R, the mismatch is at segment 62 of the Foldit protein. In both cases, the arginine (R) at segment 62 is lysine (K) in the PDB protein.

This puzzle does not have disulfide bridges.

This puzzle does not have any ligands.

This puzzle has a single chain.

See players' solutions from previous visits to this puzzle:

Complete series of revisits with top scores:

puzzle closed top solo score top solo top evo score top evo top group score top group comments
75: Antifreeze Protein 08/28/08 9,567 Franco1947 9,572 gla 9,572 Void Crushers
777: Revisiting Puzzle 75: Antifreeze Protein 09/18/13 9,640 Wilm 9,640 gloverd 9,640 Go Science
1095: Revisiting Puzzle 75: Antifreeze Protein 06/08/15 8,596 BitSpawn 8,585 mimi 8,596 Contenders
1298: Revisiting Puzzle 75: Antifreeze Protein 10/26/16 9,001 markm457 9,009 Galaxie 9,009 Anthropic Dreams
1300: Revisiting Puzzle 75 with Density: Antifreeze Protein 11/02/16 12,709 markm457 12,710 gauchomurphy 12,710 Anthropic Dreams
1562: Revisiting Puzzle 75: Antifreeze Protein 08/22/18 10,181 matosfran 10,181 matosfran 10,181 Beta Folders hat trick matosfran
1750: Revisiting Puzzle 75: Antifreeze Protein 10/30/19 10,176 Bruno Kestemont 10,170 Bruno Kestemont 10,173 Go Science hat trick Bruno K.
2030: Revisiting Puzzle 75: Antifreeze Protein 08/19/21 10,187 grogar7 10,195 Galaxie 10,195 Anthropic Dreams