Enzymes

• When an enzyme substrate complex forms, it lowers activation energy by

  • holding the two substrate molecules closer together reducing repulsion between them so they can bond more easily
  • if the enzyme is catalysing a break down reaction - fitting into the active site puts a stain on bonds in the substrate making it break up more easily
• in the lock and key model, the enzyme and substrate are perfectly complimentary
• in the induced fit model the active site is slightly altered to fit the substrate
• enzyme properties are related to their tertiary structure
• at high temperatures, an enzymes active site denatured as the high vibration of the molecules causes bonds in the enzymes tertiary structure to break
• for human enzymes the optimum temperature is around 37 degrees
• above or below the enzymes optimum pH the H+ and OH- ions found in acids and alkalis can disrupt the ionic and hydrogen bonds that hold the enzymes tertiary structure in place
• Competitive inhibitors have a similar shape to the substrate so bind the the enzymes active site and block it
• in non competitive enzyme inhibitors, the inhibitor binds to the allosteric (alternate) binding site causing the shape of the active site to change so substrate molecules can no longer fit
• in non competitive inhibitors, increasing the substrate concentration will have little effect on the rate of reaction
• Enzymes are globular proteins
• effect of temperature on enzyme activity

  
• affect of pH on enzyme activity

  
• effect of substrate concentration on enzyme activity

  
• effect of enzyme concentration on enzyme activity

  
• effect of competitive inhibitor on enzyme activity

  
• effect of non competitive inhibitor on enzyme activity