Beta-galactosidase: Difference between revisions
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(New page: Some interesting facts <cite>Muller-Hill-1996</cite> *A tetramer of 4 identical subunits *Each subunit is 120kD. *Active only as a tetramer. *Mutations in some of the codons of the N-term...) |
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*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. | *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. | *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. | |||
==Reference== | ==Reference== | ||
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#Muller-Hill-1996 isbn=3-11-014830-7 | #Muller-Hill-1996 isbn=3-11-014830-7 | ||
#Beckwith-1970 isbn=0317118099 | #Beckwith-1970 isbn=0317118099 | ||
#Ullmann-Bioessays-1992 pmid=1345751 | |||
</biblio> | </biblio> | ||
Revision as of 13:44, 21 July 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.
