Trypsin-kallikrein inhibitors from snails (Helix pomatia)

Purification and partial characterization of human neutrophil elastase inhibitors from the marine snail Cenchritis muricatus (Mollusca)

Human neutrophil elastase inhibition was detected in a crude extract of the marine snail Cenchritis muricatus (Gastropoda, Mollusca). This inhibitory activity remained after heating this extract at 60 degrees C for 30 min. From this extract, three human neutrophil elastase inhibitors (designated CmPI-I, CmPI-II and CmPI-III) were purified by affinity and reversed-phase chromatographies. Homogeneity of CmPI-I and CmPI-II was confirmed, while CmPI-III showed a single peak in reversed-phase chromatography, but heterogeneity in SDS-PAGE with preliminary molecular masses in the range of 18.4 to 22.0 kDa. In contrast, MALDI-TOF mass spectrometry of CmPI-I and CmPI-II showed that these inhibitors are molecules of low molecular mass, 5576 and 5469 Da, respectively. N-terminal amino acid sequences of CmPI-I (6 amino acids) and CmPI-II (20 amino acids) were determined. Homology to Kazal-type protease inhibitors was preliminarily detected for CmPI-II. Both inhibitors, CmPI-I and CmPI-II are able to inhibit human neutrophil elastase strongly, with equilibrium dissociation constant (Ki) values of 54.2 and 1.6 nM, respectively. In addition, trypsin and pancreatic elastase were also inhibited, but not plasma kallikrein or thrombin. CmPI-I and CmPI-II are the first human neutrophil elastase inhibitors described in a mollusk.

Isolation and characterization of a primitive interleukin-1-like protein from an invertebrate, Asterias forbesi

Interleukin 1 (IL-1) is the major immunoregulatory molecule produced by macrophages and other related cells. It acts as the molecular orchestrator of nonspecific host defense mechanisms against multifarious insults. In this study we report the characterization of an IL-1-like protein from the starfish Asterias forbesi. IL-1-like activity was found in the coelomocytes of this invertebrate and was also isolated and purified from the coelomic fluid. The coelomocytes were capable of phagocytosing latex particles and were adherent to plastic tissue culture dishes. Starfish IL-1 stimulated murine thymocyte proliferation directly and to a greater degree in the presence of submitogenic concentrations of concanavalin A. Starfish IL-1 also stimulated fibroblast proliferation and fibroblast protein synthesis. It was found to have a Mr of 29,500 and pI values of 7.5, 5.9, and 4.8. Starfish IL-1 activity was inhibited by an antibody to human IL-1. These characteristics suggest starfish IL-1 to be very similar to murine and human IL-1. The similarities to vertebrate IL-1 considered along with the evolutionary position of the starfish suggest that IL-1 is an important, ancient, and functionally conserved molecule.