Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:3.2.1.108 (
lactase
)
2,133
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The active site-directed inhibitor 4-nitrophenyl-beta-D-galactopyranosylmethyltriazene, previously shown (Fowler, A. V., Zabin, I., Sinnott, M. L., and Smith, P. J. (1978) J. Biol. Chem. 253, 5283-5285) to alkylate methionine 502 in lacZ beta-galactosidase, was used to label the second naturally occurring beta-galactosidase of Escherichia coli (ebgo). The reagent was also used to label two mutant forms of the enzyme (ebga and ebgb) selected for enhanced
lactase
activity. In the case of ebgo and ebga, 75 and 85% of the label, respectively, was incorporated into a tryptic peptide which is homologous (38% identity) to residues 483-503 of the lacZ beta-galactosidase sequence. In the ebgo and ebga enzymes, a
serine
probably is alkylated. In the case of the ebgb enzyme, 61% of the label is found on a tryptic peptide homologous (69% identity) with residues 457-468 of the lacZ beta-galactosidase. In this peptide, a glutamic acid and a tyrosine residue are both alkylated.
...
PMID:The active site regions of lacZ and ebg beta-galactosidases are homologous. 641 10
