What determines the 3-D shape of an enzyme?

Answer 1

The series of amino acids and how the different ones are bonded. Hydrogen bonding, salt bridges,disulphide bonds and both hydrophobic/hydrophobic bonds.

Answer 2

Dover7science's answer is nowhere close to the truth. The folding does not happen until well after translation and many post-translational modifications.

The lowest energy conformation model is probably closer to the truth, but still not entirely correct. It is tempting to think that small sequential changes are tried until a lowest energy conformation is achieved, but given the length of even small proteins, and an insanely fast fold rate (1 change per picosecond), this would take the average protein 1x10^56seconds to fold correctly- way longer than the universe has existed.

The shape is largely determined by water shrouds and hydrophbicity/hydrophilicity. Chaperone proteins, such as GroEL/GroES and Hsp proteins, provide the "molten globule", as an unfolded protein is known, with an enviornment with both hydrophobic and hydrophilic regions allowing small changes to the shape of the native protein. The GroEL/GroES complex functions as a sort of chewing mechanism- the unfolded protein is taken in, allowed to fold to a hydrophilic conformation, ejected, allowed to fold more, reingested, etc.. until the final conformation is achieved. The complex "knows" proper conformation by hydrophobic-hydrophobic interactions between the GroEL and the unfolded protein. As long as hydrophobic regions interact, the GroEL/GroES complex continues to work.

Answer 3

As your cell builds the protein (enzymes are proteins) the amino acids that it is built out of fit together like puzzle pieces, but in 3-D, not just 2-D. As the protein is built, the chain of amino acids kinks up, causing the 3-D shape.

Answer 4

The charge (positive/negative) and composition (hydrophilic/hydrophobic) of the "side chain" amino acids. It will fold typically to minimize the overall energy of the molecule, and maximize stability.

Good source here: http://en.wikipedia.org/wiki/Tertiary_structure