In this programme the two major models of co-operativity of enzymes are discussed in detail as well as the experimental test devised to decide between them.
|Module code and title:
|S322, Biochemistry and molecular biology
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|BBC Open University
|`Fine tuning'; Co-operativity; CTP synthetase; Environmental fluctuations; Flexible enzyme; Negative co-operativity; Sequential model; Symmetry model
|Shots of diagrams showing the two major models of enzyme co-operativity. Professor Koshland introduces the programme. Koshland, pointing to a schematic diagram on a blackboard, explains the principles behind the sequential model devised by him. He points out how this model explains co-operativity in enzymes. Again using a blackboard, Koshland examines the symmetry model which Monod, Wyman and Changeux developed to explain enzyme co-operativity. An animated graph shows the results from several experiments which were conducted to test the validity of the two models. Results are the same for both. Koshland then explain a mathematical technique which demonstrated that, by using his sequential model, a state of negative co-operativity for enzymes was predicted. This concept could not be handled by the symmetry model. More animated graphs and the blackboard help illustrate his points. Koshland explains, in greater detail, why the Monod, Wyman, Changeux symmetry model cannot account for negative co-operativity. Animated captions and the blackboard are used. Using a graph drawn on the blackboard, Koshland shows the implications of the three possible co-operativity patterns for the control of enzyme activity. Continuing his use of the blackboard, Koshland discusses the implications, for the living of the three patterns of enzyme co-operativity. Using animated diagrams, Koshland summarises the way in which, according to his sequential model, enzymes can respond to environmental fluctuations in a sophisticated way analogous to fine-tuning of machinery. Koshland briefly sums up the programme.
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