Revisiting puzzle/75: Antifreeze Protein

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:

 
anqasvvanqlipintaltlvmmrsevvtpvgipaediprlvsmqvnravplgttlmpdmvrgyaa

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:

• Puzzle 777
• Puzzle 1095
• Puzzle 1562
• Puzzle 1750

Complete series of revisits with top scores: