The functioning of the enzyme is determined by the shape of the protein. It recognizes, confines and orients the substrate in a particular direction. Fit of the enzyme and substrate at the active site. Image from the Internet. The induced fit hypothesis suggests that the binding of the substrate to the enzyme alters the structure of the enzyme, placing some strain on the substrate and further facilitating the reaction.
Cofactors are nonproteins essential for enzyme activity.
Coenzymes are nonprotein organic molecules bound to enzymes near the active site. Note the change in enzyme shape after the substrate is added. Graphic modified from the Internet. Increases in temperature will speed up the rate of nonenzyme mediated reactions, and so temperature increase speeds up enzyme mediated reactions, but only to a point. When the temperature drops, the enzyme regains its shape.