Streptavidin is a a bacterial protein (from Streptomyces avidinii) that has an exceptionally high binding affinity for biotin (B7). Streptavidin-biotin binding is one of the strongest known non-covalent interactions and is highly resistant to many conditions that would typically cause dissociation (such as organic solvents, denaturants, detergents, and extreme temperatures or pH). Streptavidin's afinity for biotin can be employed in a variety of experimental uses, from purifications to standards, to means of detection or pull down experiments.
Alkaline Phosphatase is an enzyme which removes phosphate groups from a variety of substate molecules. As the name implies, this enzyme functions best under basic pH. Alkaline Phosphatase can be utilized in molecular biology in DNA ligation experiments (keeping the DNA linear), radiolabeling preparations, and a detection mediator in ELISA experiments.