Skip the theory and go straight to: How to determine Km and Vmax A simple chemical reaction with a single substrate shows a linear relationship between the rate of formation of product and the concentration of substrate, as shown below: For an enzyme-catalysed reaction, there is usually a hyperbolic relationship between the rate of reaction and the concentration of substrate, as shown below:
Induced fit hypothesis In this model the enzyme molecule changes shape as the substrate molecules gets close. The change in shape is 'induced' by the approaching substrate molecule. This more sophisticated model relies on the fact that molecules are flexible because single covalent bonds are free to rotate.
Temperature As the temperature rises, reacting molecules have more and more kinetic energy. This increases the chances of a successful collision and so the rate increases. There is a certain temperature at which an enzyme's catalytic activity is at its greatest see graph.
This optimal temperature is usually around human body temperature Above this temperature the enzyme structure begins to break down denature since at higher temperatures intra- and intermolecular bonds are broken as the enzyme molecules gain even more kinetic energy.
There is a pH at which its activity is greatest the optimal pH. This is because changes in pH can make and break intra- and intermolecular bonds, changing the shape of the enzyme and, therefore, its effectiveness. Concentration of enzyme and substrate The rate of an enzyme-catalysed reaction depends on the concentrations of enzyme and substrate.
As the concentration of either is increased the rate of reaction increases see graphs. For a given enzyme concentration, the rate of reaction increases with increasing substrate concentration up to a point, above which any further increase in substrate concentration produces no significant change in reaction rate.
This is because the active sites of the enzyme molecules at any given moment are virtually saturated with substrate.
See graph Provided that the substrate concentration is high and that temperature and pH are kept constant, the rate of reaction is proportional to the enzyme concentration.
See graph Inhibition of enzyme activity Some substances reduce or even stop the catalytic activity of enzymes in biochemical reactions.
They block or distort the active site. These chemicals are called inhibitors, because they inhibit reaction. Inhibitors that occupy the active site and prevent a substrate molecule from binding to the enzyme are said to be active site-directed or competitive, as they 'compete' with the substrate for the active site.
Inhibitors that attach to other parts of the enzyme molecule, perhaps distorting its shape, are said to be non-active site-directed or non competitive. Immobilized enzymes Enzymes are widely used commercially, for example in the detergent, food and brewing industries.
Protease enzymes are used in 'biological' washing powders to speed up the breakdown of proteins in stains like blood and egg.
Pectinase is used to produce and clarify fruit juices. Problems using enzymes commercially include: This has a number of commercial advantages:Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States.
Fluoride Recommendations Work Group. Steven M. Adair, D.D.S., M.S. School of Dentistry Medical College of Georgia Augusta, Georgia. Published: Mon, 5 Dec Determination of the effect of enzyme concentration on catalysis using starch an amylase.
INTRODUCTION. Enzymes are said to be catalytic proteins which increases the rate of a chemical reaction without being altered in the process of that reaction. . The Effect of Activator Concentration on the Rate of Reaction of Fungal Amylase Aim Investigate the effect of Activator concentration (Calcium) on the rate of reaction of enzyme (fungal amylase) using Starch as a substrate.
Introduction Enzymes are made of . Investigating the Effect of Substrate Concentration on Catalase Reaction - Investigating the Effect of Substrate Concentration on Catalase Reaction Planning -Aim: The aim of the experiment is to examine how the concentration of the substrate (Hydrogen Peroxide, H2O2) affects the rate of reaction of the enzyme (Catalase).
The rate of formation of product now depends on the activity of the enzyme itself, and adding more substrate will not affect the rate of the reaction to any significant effect. The rate of reaction when the enzyme is saturated with substrate is the maximum rate of reaction, Vmax.
The effect of substrate concentration on enzyme activity. Skip the theory and go straight to: How to determine Km and Vmax A simple chemical reaction with a single substrate shows a linear relationship between the rate of formation of product and the concentration of substrate, as shown below.