Beta-galactosidase Enzyme Donor
Catalog #: P2010004 (1 mg)
Beta-galactosidase Enzyme Donor (also known as Alpha Peptide fragment) can complement the Beta-galactosidase Enzyme Acceptor (also known as Omega domain) to reconstitute an active Beta-galactosidase enzyme. This phenomenon, known as alpha complementation, can be exploited to develop assays by conjugating the Beta-galactosidase Alpha Peptide fragment to various analytes. The sequence of the enzyme donor has been specifically engineered to include a unique central cysteine that can be used for analyte conjugation.
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Beta-galactosidase Enzyme Donor (alpha peptide)
|Product Data Sheet|
|Other Names||Beta-galactosidase Alpha Peptide|
|Supplied as||White lyophilized powder.|
|Molecular Weight||11 kDa (99 amino acids)|
|Purity||>95% (SDS PAGE)|
|Storage||-20°C. Avoid repeated freeze/thaw cycles.|
|Suggested buffer||Beta-galactosidase Enzyme-Donor Stabilization Buffer (B2010001)|
|Keywords||Beta-galactosidase Alpha Peptide, Enzyme Donor, alpha complementation, LacZ.|
|Related products||Beta-galactosidase Enzyme Acceptor (Omega Domain), Beta-galactosidase Enzyme-Donor Stabilization Buffer, Beta-galactosidase Alpha Complementation Kit.|
About Beta-galactosidase Alpha Complementation
Beta-galactosidase Alpha-Complementation is a biochemical phenomenon first documented by Agnes Ullmann, while working in the lab of François Jacob and Jacques Monod. By means of molecular cloning, the native E. coli β-galactosidase enzyme can be split in two inactive fragments of different sizes. The smaller fragment, known as the alpha-peptide or enzyme donor, is about 100 amino residues in length and is inactive on its own (incapable of hydrolyzing a β-galactosidase substrate). The larger fragment, known as the omega fragment or enzyme acceptor, is about 900 amino residues in length and is also inactive on its own. Upon mixing the enzyme donor with the enzyme acceptor, the β-galactosidase enzyme is reconstituted and is now capable of hydrolyzing colorimetric substrates such as ONPG.
Both enzyme donor and enzyme acceptor can be cloned and expressed in special E. coli strains to yield highly pure, zero-background enzyme fragments (i.e. an enzyme donor and enzyme acceptor without measurable catalytic activities, when assayed individually). Interestingly, it was discovered that various analytes can be conjugated to the enzyme donor moiety and the enzyme donor-enzyme acceptor association modulated by an analyte-binding molecule (such as an antibody). As a result, an alpha-complementation-based assay can be developed.
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1- Matthews BW. The structure of E. coli beta-galactosidase. C R Biol. 2005 Jun;328(6):549-56.
2- Zeilstra-Ryalls JH, Somerville RL. Protein-protein interaction in the alpha-complementation system of beta-galactosidase. Curr Top Cell Regul. 1992;33:81-104.