Here you will find some stuff about enzyme kinetics. The study of the rate at which an enzyme works is called enzyme kinetics.
http://web.campbell.edu/faculty/chazotte/
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/EnzymeKinetics.html
http://www.columbia.edu/itc/chemistry/chem-c2407/hw/ENZYME_KINETICS.pdf
www.glutxi.umassmed.edu/grad/GradKinetics.pdf