Because glycine is the most flexible amino acid (due to its lack of a sidechain), it will respond readily and rather predictably to manipulation. The glycine hinge is a tactic used to shape a section of a loop containing at least one glycine. It is most useful when a player has some idea of where other secondary structures should go, and wants to bend the loop in a way that will put them in the appropriate places while not dragging down the local score too much.
First, freeze the amino acids next to the glycine, while leaving the glycine unfrozen. Then band the frozen amino acids in the direction you'd like them to move — this will correspond to the way you want the hinge to bend. Finally, global wiggle. The glycine will usually flex into a new shape, and if this helps your compactness, hydrophobicity, or hydrogen bond arrangement, the score will often go up!
- If you don't gain points at first from a glycine hinge, don't despair. Release the bands, unlock the puzzle, and global wiggle again. Often a glycine hinge will get you points on the rebound.
- The glycine hinge works because (apparently) there are few points to be gained or lost by bending a glycine.
- If you want to keep the glycine bent after applying the hinge, lock it while unlocking the rest of the hinge. Then global or local wiggle.