Localization of peptidases in lactococci.
The localization of two aminopeptidases, an X-prolyl-dipeptidyl aminopeptidase, an endopeptidase, and a tripeptidase in Lactococcus lactis was studied. Polyclonal antibodies raised against each purified peptidase are specific and do not cross-react with other peptidases. Experiments were performed by immunoblotting after cell fractionation and by electron microscopy of immunogold-labeled peptidases. All peptidases were found to be intracellular. However, immunogold studies showed a peripheral labeling of the X-prolyl-dipeptidyl aminopeptidase, the tripeptidase, and the endopeptidase. This peripheral location was further supported by the detection of these three enzymes in cell membrane fractions in which none of the two aminopeptidases was present.
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Department of Microbiology, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands, and Station de Recherches Laitieres, Institute National de la Recherche Agronomique, 78350 Jouy-en-Josas, and Laboratoire de Génie des Procédés Biotechnologiques Agro-alimentaires, Institute National de la Recherche Agronomique, 7850 Thiverval-Grignon, France.
Chapot-Chartier
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Rousseau
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Boquien
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Gripon
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Konings
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