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Ligands can either have positive cooperativity, negative cooperativity, or non-cooperativity. The sigmoidal shape of hemoglobin's oxygen-dissociation curve results from cooperative binding of oxygen to hemoglobin. An example of positive cooperativity is the binding of oxygen to hemoglobin.
The first description of cooperative binding to a multi-site protein was developed by A.V. Hill. [4] Drawing on observations of oxygen binding to hemoglobin and the idea that cooperativity arose from the aggregation of hemoglobin molecules, each one binding one oxygen molecule, Hill suggested a phenomenological equation that has since been named after him:
David Johnson, Deutsch's student in the study of social psychology, with his brother Roger Johnson, a science educator, and their sister, educator Edye Johnson Holubec, further developed positive interdependence theory as part of their research and work in teacher and professional training at the Cooperative Learning Center at the University of Minnesota (founded in 1969).
Positively cooperative binding: Once one ligand molecule is bound to the enzyme, its affinity for other ligand molecules increases. For example, the Hill coefficient of oxygen binding to haemoglobin (an example of positive cooperativity) falls within the range of 1.7–3.2. [5] <.
In cooperativity, the initial ligand binding affects the host's affinity for subsequent ligands. In positive cooperativity, the first binding event enhances the affinity of the host for another ligand. Examples of positive and negative cooperativity are hemoglobin and aspartate receptor, respectively. [11] General Host–Guest Binding. (1.)
Ligand binding may also result in negative cooperativity, or a reduced affinity for the ligand at the next binding site, a feature that makes the KNF model distinct from the MWC model, which suggests only positive cooperativity. [2] [3] It is named KNF after Koshland, Némethy and Filmer, who first suggested the model. [1]
The positive reciprocity norm is a common social expectation in which a person who helps another person can expect positive feedback whether in the form of a gift, a compliment, a loan, a job reference, etc. In social psychology, positive reciprocity refers to responding to a positive action with another positive action (rewarding kind actions).
The binding problem refers to the overall encoding of our brain circuits for the combination of decisions, actions, and perception. It is considered a "problem" due to the fact that no complete model exists. The binding problem can be subdivided into the four areas of perception, neuroscience, cognitive science, and the philosophy of mind. It ...