amastatin and leuhistin

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) x g(-1); P. redivivus, 1.23 +/- 0.18m AU min(-1) microg(-1). Each is inhibited competitively by amastatin (C. elegans IC50 = 0.46 microM; P. redivivus IC50 = 15.90 microM) and non-competitively by leuhistin (C. elegans IC50 = 3.00 microM; P. redivivus IC50 = 37.35 microM). 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.

Topics: Amino Acids; Aminopeptidases; Animals; Anti-Bacterial Agents; Caenorhabditis elegans; Dose-Response Relationship, Drug; Imidazoles; In Vitro Techniques; Insect Hormones; Nematoda; Oligopeptides; Peptides; Protease Inhibitors; Pyrrolidonecarboxylic Acid; Species Specificity; Substance P

Aminopeptidase-like activities in crude whole body extracts of the free-living nematode Caenorhabditis elegans and the plant parasitic soybean cyst nematode Heterodera glycines were examined. General characteristics including pH optima, heat lability, and inactivation of enzyme by organic solvent were the same for the two species. All developmental stages of H. glycines exhibited activity. In older females, activity was present primarily in the eggs. Affinity for the substrate L-alanine-4-nitroanilide was the same regardless of the stage examined, and was similar for the two species (m for C. elegans and m for H. glycines). Nearly all (>95%) of C. elegans aminopeptidase-like activity was present in the soluble fraction of the extract, while H. glycines activity was distributed between the soluble and membrane fractions. Specific activities of the soluble enzymes were highest in C. elegans and H. glycines juveniles. The C. elegans enzyme was susceptible to a number of aminopeptidase inhibitors, particularly to amastatin and leuhistin, each of which inhibited aminopeptidase-like activity more than 90% at 90 microm. In H. glycines, aminopeptidase-like activity was inhibited 39% by amastatin at 900 microm. The apparent molecular weight of the soluble C. elegans enzyme is 70-80 kDa. Some activity in H. glycines is present in the 70-80 kDa range, but most activity (80-90%) is associated with a very high molecular weight (>240 kDa) component.

Topics: Amino Acids; Aminopeptidases; Animals; Anti-Bacterial Agents; Antinematodal Agents; Caenorhabditis elegans; Enzyme Inhibitors; Glycine max; Hydrogen-Ion Concentration; Imidazoles; Molecular Weight; Nematoda; Peptides

The enzymatic changes in murine spleen caused by the administration for 20 successive days of various inhibitors of aminopeptidase N (leucocyte antigen CD13) have been compared. When compared with the control (saline), most of the inhibitors significantly suppressed splenic enzyme activities including those of ectoenzymes. A multivariate study indicated that the in vivo effects of the inhibitors were closely related to their inhibitory actions in vitro.

Topics: Amino Acids; Animals; Anti-Bacterial Agents; CD13 Antigens; Endopeptidases; Glycoside Hydrolases; Guanidines; Hydroxamic Acids; Imidazoles; Leucine; Male; Mice; Mice, Inbred BALB C; Oligopeptides; Peptides; Protease Inhibitors; Spleen