Beta-galactosidase

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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 &beta;-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 &beta;-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 15:44, 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.

Reference

  1. isbn:3-11-014830-7. [Muller-Hill-1996]
  2. isbn:0317118099. [Beckwith-1970]
  3. Ullmann A. . pmid:1345751. PubMed HubMed [Ullmann-Bioessays-1992]
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