from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. Any of various enzymes that are produced by certain bacteria, including most strains of staphylococci, and that hydrolyze and inactivate penicillin. They are used in medicine to treat allergic reactions to penicillin. Also called beta-lactamase.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A specific type of beta-lactamase showing specificity for penicillins.

from the GNU version of the Collaborative International Dictionary of English

  • n. An enzyme which destroys the antibacterial activity of penicillin by hydrolyzing the amide bond in the beta-lactam ring. Many penicillinases are known, and are produced by a wide variety of bacteria. The production of penicillinase is one of the mechanisms by which bacteria may become resistant to penicillins. Penicillinase production in various bacterial species may be induced, i.e., it may occur only when stimulated by the presence of penicillin in the culture medium, or it may be constitutive, i.e., it may occur whenever the cells are producing protein. Molecular weights of the various penicillinases tend to cluster near 50,000.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. enzyme produced by certain bacteria that inactivates penicillin and results in resistance to that antibiotic


from Wiktionary, Creative Commons Attribution/Share-Alike License

penicillin +‎ -ase


  • An example would be the bacteria that secrete penicillinase, which is an enzyme that destroys penicillin.

    Cities In Flight

  • Recall that Axe did not work with the native TEM-1 penicillinase, but rather with a variant that had a lower activity.

    Axe (2004) and the evolution of enzyme function - The Panda's Thumb

  • The object of interest was the so-called large domain of the TEM-1 penicillinase, an enzyme that breaks down antibiotics related to penicillin.

    Axe (2004) and the evolution of enzyme function - The Panda's Thumb

  • Therefore it is necessary to treat breast infections with a penicillinase-resistant antibiotic such as either flucloxacillin or erythromycin.

    Chapter 39

  • - Antibacterial (antibiotic) of the penicillin group, acting specifically against penicillinase producing staphylococci

    Chapter 4

  • Since 1948 his research topics have included carbohydrate-amino acid relationship in nervous tissue, a study of the mode of action of insulin, fermentation technology, 6-aminopenicillanic acid and penicillinase-stable penicillins, lysergic acid production in submerged culture, and the isolation of new fungal metabolites.

    Ernst B. Chain - Biography

  • C. Resistance to penicillin is mediated both by plasmid-encoded penicillinase and by changes in chromosome-encoded proteins that control the permeability of the drug.

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  • Staphylococcus aureus (MRSA), resulting in the concept that MRSA has emerged on a few occasions after penicillinase-stable β-lactam antibiotics were introduced to clinical practice, followed by intercontinental spread of individual clones.

    Proceedings of the National Academy of Sciences current issue

  • Axe’s numbers tell us about the apparent isolation of the low-activity variant, but reveal little nor can it be expected to about the “isolation” or evolution of TEM-1 penicillinase.

    Axe (2004) and the evolution of enzyme function - The Panda's Thumb

  • Before I discovered I wasn't cut out to be a bench biochemist, my undergraduate research was on "Competitive inhibition of penicillinase by notalysin, a

    Citizendium, the Citizens' Compendium - Recent changes [en]


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