Beta-galactosidase
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(Difference between revisions)
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*A mutant with a deletion of everything past residue 60 (i.e. it expresses only the first 60 N-terminal amino acids) does not produce any active β-galactosidase. | *A mutant with a deletion of everything past residue 60 (i.e. it expresses only the first 60 N-terminal amino acids) does not produce any active β-galactosidase. | ||
*You can measure lacZ activity using flow cytometry. See [http://www.cyto.purdue.edu/flowcyt/research/micrflow/jepras/jepras2.htm A flow cytometric study of stationary phase gene expression in E.coli using lacZ reporter gene fusion] | *You can measure lacZ activity using flow cytometry. See [http://www.cyto.purdue.edu/flowcyt/research/micrflow/jepras/jepras2.htm A flow cytometric study of stationary phase gene expression in E.coli using lacZ reporter gene fusion] | ||
| - | **This paper uses [http://probes.invitrogen.com/media/pis/mp02904.pdf C<sub>12</sub>FDG] from Invitrogen | + | **This paper uses [http://probes.invitrogen.com/media/pis/mp02904.pdf C<sub>12</sub>FDG] from Invitrogen. However, FDG might be a better substrate in gram-negative bacteria like ''Escherichia coli'' <cite>Plovins-ApplEnvironMicrobio-1994</cite> |
==Reference== | ==Reference== | ||
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#Beckwith-1970 isbn=0317118099 | #Beckwith-1970 isbn=0317118099 | ||
#Ullmann-Bioessays-1992 pmid=1345751 | #Ullmann-Bioessays-1992 pmid=1345751 | ||
| + | #Plovins-ApplEnvironMicrobio-1994 pmid=7811104 | ||
</biblio> | </biblio> | ||
[[Category:Material]] [[Category:Enzyme]] [[Category:Reporter]] | [[Category:Material]] [[Category:Enzyme]] [[Category:Reporter]] | ||
Revision as of 18:03, 17 September 2007
Some interesting facts [1]
- A tetramer of 4 identical subunits
- Each subunit is 120kD.
- Active only as a tetramer.
- Mutations in some of the codons of the N-terminal 60aa or C-terminal 100aa results in an inactive, dimeric β-galactosidase. [2]
- If the above sequences are deleted, the missing protein fragment can be replaced by the corresponding peptide. This is called intracistronic alpha or omega complementation respectively.
- Its N-terminal 23 residues can be replaced by any amino acid residues without affecting the enzymatic activity.
- A mutant with an internal deletion of codons 21-41 of the lacZ gene does not produce any active β-galactosidase.
- A mutant with a deletion of everything past residue 60 (i.e. it expresses only the first 60 N-terminal amino acids) does not produce any active β-galactosidase.
- You can measure lacZ activity using flow cytometry. See A flow cytometric study of stationary phase gene expression in E.coli using lacZ reporter gene fusion
Reference
- Benno Muller-Hill. The Lac Operon. Walter de Gruyter. isbn:3-11-014830-7.
- isbn:0317118099.
- Plovins A, Alvarez AM, Ibañez M, Molina M, and Nombela C. . pmid:7811104.
- Ullmann A. . pmid:1345751.
