cooperative binding

Examples of cooperative binding in the following topics:

• RBC Physiology

  • Each hemoglobin molecule contains four iron-binding heme groups, which are the site of oxygen (O2) binding.
  • The binding of oxygen is a cooperative process.
  • Hemoglobin bound oxygen causes a gradual increase in oxygen-binding affinity until all binding sites on the hemoglobin molecule are filled.
  • As a result, the oxygen-binding curve of hemoglobin (also called the oxygen saturation or dissociation curve) is sigmoidal, or S-shaped, as opposed to the normal hyperbolic curve associated with noncooperative binding.
  • Hemoglobin can also bind to carbon dioxide, which creates carbamino-hemoglobin.

• Repression of Anabolic Pathways

  • Sites of DNA sequences where regulatory proteins bind are called enhancer sequences.
  • The binding changes the structural conformity of the repressor such that it binds to the operator region for the operon that synthesizes tryptophan, preventing their expression and thus suspending production.
  • When lactose is present, it binds to the repressor, causing it to detach from the DNA strand.
  • Two monomers (of four total) cooperate to bind each DNA operator sequence.
  • Monomers (red and blue) contain DNA binding and core domains (labeled) which are connected by a linker (labeled).

• Catabolite Activator Protein (CAP): An Activator Regulator

  • When glucose levels decline in the cell, accumulating cAMP binds to the positive regulator catabolite activator protein (CAP), a protein that binds to the promoters of operons that control the processing of alternative sugars, such as the lac operon.
  • Two cAMP molecules bind dimeric CAP with negative cooperativity and function as allosteric effectors by increasing the protein's affinity for DNA.
  • When cAMP binds to CAP, the complex binds to the promoter region of the genes that are needed to use the alternate sugar sources .
  • In these operons, a CAP-binding site is located upstream of the RNA-polymerase-binding site in the promoter.
  • This cAMP binds to the CAP protein, a positive regulator that binds to an operator region upstream of the genes required to use other sugar sources.

• Cooperation

  • The legislature is an example of a cooperative act.
  • Without cooperation, no institution beyond the individual would develop; any group behavior is an example of cooperation.
  • Coerced cooperation is when cooperation between individuals is forced.
  • Voluntary cooperation is cooperation to which all parties consent.
  • Unintentional cooperation is a form of cooperation in which individuals do not necessarily intend to cooperate but end up doing so because of aligning interests.

• Immunoassays for Disease

  • All work cooperatively to eliminate immunogenic foreign substances from the body.
  • Most assays rely on the formation of large immune complexes when an antibody binds to a specific antigen which can be detected in solution or in gels.

• Durkheim and Social Integration

  • The collective consciousness binds individuals together and creates social integration.
  • In traditional societies, people are self-sufficient, and therefore society has little need for cooperation and interdependence.
  • Institutions that require cooperation and agreement must often resort to force and repression to keep society together.
  • Specialization and the division of labor require cooperation.

• The United Nations

  • The United Nations (UN) is an intergovernmental, international organization consisting of all 193 states in the world, whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and the achievement of world peace.
  • The United Nations was established to replace the flawed League of Nations, in order to maintain international peace and promote cooperation in solving international economic, social and humanitarian problems.
  • The Economic and Social Council promotes international economic and social progress through cooperation and development.
  • The Universal Declaration of Human Rights, though not legally binding, was adopted by the General Assembly in 1948 as a common standard of achievement for all.

• Blocking of Hormone Receptors

  • Binding occurs as a result of noncovalent interaction between the receptor and its ligand, at locations called the binding site on the receptor.
  • Once bound, an antagonist will block agonist binding.
  • These antagonists bind to a distinctly separate binding site from the agonist, exerting their action to that receptor via the other binding site.
  • They do not compete with agonists for binding at the active site.
  • The affinity of an antagonist for its binding site (Ki), i.e. its ability to bind to a receptor, will determine the duration of inhibition of agonist activity.

• Cooperatives

  • Cooperatives are independent and democratic organizations in which each member has equal control.
  • While it is a business model, it can be applied to a wide variety of other circumstances such as consumer cooperatives, housing cooperatives, credit unions, worker cooperatives, and various non-profit formats.
  • Another benefit is that cooperatives are often invested in solving social issues and providing value in their communities.
  • No individual owner can derive profit exceeding the fixed interest, nor gain greater control over the operations of the cooperative.
  • Consider the potential advantages and disadvantages of a cooperative as an organizational model

• Tests That Differentiate Between T Cells and B cells

  • These two cell types can function independently or cooperatively to defend the body against pathogens.
  • Traditionally, T-lymphocytes were defined by their ability to form E-rosettes when they bind selectively to sheep erythrocytes.