Properties of Enzymes as Catalyst

Properties of Enzymes as Catalyst - reaction is reached...

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Properties of Enzymes as Catalyst Chemical reactions depend on molecules being properly oriented and of sufficient energy to cause chemical changes to occur. (Demonstration) The rate of reaction can be accelerated through the use of catalyst . (Demonstration). Catalyst operate by lowering the energy needed to activate the reactive molecules (Fig. 1 or Figure 2.22 in Text). Biological reactions are accomplished by catalyst called enzymes - proteins that possess specific catalytic activities. The term enzyme actually means "in yeast". There are more than 2000 different known enzymes. Nearly every chemical reaction is catalyzed by an enzyme. Molecules used in the fermentation of sugar to form alcohol were the first enzymes to be isolated. Enzymes catalyze the series of reactions by which metabolic pathways breakdown compounds obtained from the environment; and they degrade and reconstruct the components needed to maintain the organism. An enzyme may create an environment in which the equilibrium of a particular
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Unformatted text preview: reaction is reached more rapidly than is possible by spontaneous reaction, but it cannot alter the equilibrium itself. Certain catalysts known as ribozymes are made of RNA. At this point in the course, however, we are only dealing with enzymes which are proteins. A typical enzyme accelerates a reaction 10^8 to 10^10 fold. Some can increase as high as 10^15 fold. In order for a chemical reaction to proceed, the substrate must first be converted to a higher energy state, the transition state. The energy required to reach the transition state is the activation energy. Enzymes are highly specific , each catalyzes only a single reaction or set of closely related reactions. Ex: Beta-galactosidase is moderately specific. It will split lactose but it will also split any disaccharide joined with a beta-galactoside bond. Phosphorylase kinase acts with absolute specificity with a single substrate - glycogen phosphorylase....
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This document was uploaded on 11/03/2011 for the course BIOLOGY MCB2010 at Broward College.

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