Virtuelle (Nano) Welten PDB Molecule of the Month 90: Fatty Acid Synthase

Step-by-Step Construction

Plants and bacteria, on the other hand, build their fatty acids using a bunch of separate enzymes. Four enzymes from bacteria are shown here, from PDB entries 1kas, 1i01, 1u1z, and 1dfg. Together, they add two carbons to the growing chain and then reduce them to the proper state. The small protein in the middle, called acyl carrier protein (PDB entry 2fae), acts as a shuttle that carries the fatty acid chain from enzyme to enzyme as the changes are made. You might wonder which approach is better: a bunch of separate enzymes or a big complex like the one on the previous page. Our fatty acid machine is highly efficient. Since everything happens in one big protein chain, the growing fatty acid can be shuttled very efficiently from site to site. The disadvantage, however, is that our multienzyme machine is hardwired to produce mainly one fatty acid: palmitic acid. In bacteria and plants, other enzymes can be added to the collection to produce a whole variety of different fatty acids, although a bit less efficiently.