Enzymes are biological molecules (typically proteins) that significantly speed up the rate of virtually all of the chemical reactions that take place within cells. ... The molecules that an enzyme works with are called substrates. The substrates bind to a region on the enzyme called the active site.
Siphons in Mollusca are tube-like structures in which water (or, more rarely, air) flows. The water flow is used for one or more purposes such as locomotion, feeding, respiration, and reproduction.
The siphon propels the squid through the water in the opposite direction to which the siphon is pointing, much like jet propulsion. To use this jet propulsion, the squid takes in water through the large opening and then closes off the opening.