PMID- 1908220
OWN - NLM
STAT- MEDLINE
DA  - 19910917
DCOM- 19910917
LR  - 20091118
IS  - 0264-6021 (Print)
IS  - 0264-6021 (Linking)
VI  - 277 ( Pt 3)
DP  - 1991 Aug 1
TI  - Active-site serine mutants of the Streptomyces albus G beta-lactamase.
PG  - 647-52
AB  - By using site-directed mutagenesis, the active-site serine residue of the
      Streptomyces albus G beta-lactamase was substituted by alanine and cysteine. Both
      mutant enzymes were produced in Streptomyces lividans and purified to
      homogeneity. The cysteine beta-lactamase exhibited a substrate-specificity
      profile distinct from that of the wild-type enzyme, and its kcat./Km values at pH
      7 were never higher than 0.1% of that of the serine enzyme. Unlike the wild-type 
      enzyme, the activity of the mutant increased at acidic pH values. Surprisingly,
      the alanine mutant exhibited a weak but specific activity for benzylpenicillin
      and ampicillin. In addition, a very small production of wild-type enzyme,
      probably due to mistranslation, was detected, but that activity could be
      selectively eliminated. Both mutant enzymes were nearly as thermostable as the
      wild-type.
AD  - Centre d'lngenierie des Proteines, Universite de Liege, Belgium.
FAU - Jacob, F
AU  - Jacob F
FAU - Joris, B
AU  - Joris B
FAU - Frere, J M
AU  - Frere JM
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - ENGLAND
TA  - Biochem J
JT  - The Biochemical journal
JID - 2984726R
RN  - 0 (Oligonucleotides)
RN  - 56-45-1 (Serine)
RN  - 60-24-2 (Mercaptoethanol)
RN  - EC 3.5.2.6 (beta-Lactamases)
SB  - IM
MH  - Base Sequence
MH  - Binding Sites
MH  - DNA Mutational Analysis
MH  - Hot Temperature
MH  - Hydrogen-Ion Concentration
MH  - Kinetics
MH  - Mercaptoethanol/chemistry
MH  - Molecular Sequence Data
MH  - Oligonucleotides/chemistry
MH  - Protein Denaturation
MH  - Serine
MH  - Streptomyces/*enzymology/genetics
MH  - Structure-Activity Relationship
MH  - beta-Lactamases/chemistry/*genetics/metabolism
PMC - PMC1151291
OID - NLM: PMC1151291
EDAT- 1991/08/01
MHDA- 1991/08/01 00:01
CRDT- 1991/08/01 00:00
PST - ppublish
SO  - Biochem J. 1991 Aug 1;277 ( Pt 3):647-52.