4 Enzymes, bioenergetics

4 Enzymes, bioenergetics - Biology141(Physiology 1:00 AM...

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4/6/08 1:00 AM Biology141 (Physiology) Page 1 of 4 https://courses.bio.psu.edu/spring2008/biol141/Lecture%204(2008).htm Biology141 (Physiology) Lecture 4 M.Whim ENZYMES AND BIOENERGETICS [1]. ENZYMES. enzymes are biological catalysts. 3 characteristics of a catalyst are: 1. 2. 3. most biological catalysts are proteins. end in ase named according to their activity (synthases: catalyze dehydration, phophatases: ? kinases: ?). highly specific in the reaction that is catalyzed. enzymes lower the activation energy of a reaction (which is what?). (a). How does an enzyme lower activation energy? the substrate molecules fit into the active site of the enzyme (the part that catalyzes the reaction). a popular model that explains some aspects of enzyme activity is the lock-and-key model ; the enzyme acts to increase the proximity of the substrates (i.e. the reactant molecules). why might it be useful to measure the plasma levels of intracellular enzymes? (b). What regulates enzyme activity? regulation of enzyme activity is very important. inappropriate activity can have dramatic physiological consequences. (i). Temperature and pH as for non-catalyzed reactions, increasing temperature increases the reaction rate. maximal rate is around 37 degrees C, but above this it decreases. Why? pH has a similar effect in that there is a pH optimum.
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