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Aminopeptidases in Caenorhabditis elegans and Panagrellus redivivus: detection using peptide and non-peptide substrates

Published online by Cambridge University Press:  12 April 2024

E.P. Masler*
Affiliation:
Nematology Laboratory, United States Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, BARC-West, Beltsville, MD 20705-2350, USA
*
*Fax: 301 504 5589 Email: maslere@ba.ars.usda.gov

Abstract

Aminopeptidase activities were detected in extracts of the free-living nematodes Caenorhabditis elegans and Panagrellus redivivus using the aminoacyl substrate L-alanine-4-nitroanilide. The activities exhibited similarities in Km (C. elegans = 2.22 mM; P. REDIVIVUS = 2.09 Mm) and specific activity (C. elegans=1.38±0.43 mAU min-1 μg-1; P. redivivus, 1.23±0.18 mAU min-1 μg-1). Each is inhibited competitively by amastatin (C. elegans IC50=0.46 μm; P. redivivus IC50=15.90 μm) and non-competitively by leuhistin (C. elegans IC50=3.00 μm; P. redivivus IC50=37.35 μm). The bioactive peptides adipokinetic hormone and substance P decrease the apparent aminopeptidase activities of each extract suggesting that the peptides compete with the Ala-pNA as substrates. With each extract, adipokinetic hormone appeared to be the more effective substrate. Digestion of adipokinetic hormone by C. elegans and P. redivivus extracts in the presence and absence of 1 mm amastatin produced distinct chromatographic profiles that suggest different digestion patterns for the two species. However, amastatin had clear effects on chromatographic profiles from each species indicating that an aminopeptidase is involved in the digestion of the peptide substrates. The data presented indicate that extracts of free-living nematodes are capable of metabolizing peptide hormones, and that this metabolism involves substrate-selective aminopeptidases.

Information

Type
Review Article
Copyright
Copyright © Cambridge University Press 2002

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