Isolation and complete amino acid sequence of two fibrinolytic proteinases from the toxic Saturnid caterpillar Lonomia achelous

Tany Amarant, William Burkhart, Harry LeVine, Carmen L. Arocha-Pinango, Indu Parikh

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55 Scopus citations


The major toxic and fibrinolytic activity of the saliva and hemolymph of the larval form of Lonomia achelous was purified to homogeneity by a combination of metal chelate and affinity chromatography. Two apparent isozymes, Achelase I (213 amino acids, pIcalc = 10.55) and Achelase II (214 amino acids, pIcalc = 8.51), were sequenced by automated Edman degradation, and their C-termini confirmed by Fourier-transform mass spectrometry. The calculated molecular weights (22 473 and 22 727) correspond well to Mr estimates of 24 000 by SDS-PAGE. No carbohydrate was detected during sequencing. The enzymes degraded all three chains of fibrin, α > β ≫ γ, yielding a fragmentation pattern indistinguishable from that produced by trypsin. Chromogenic peptides S-2222 (Factor Xa and trypsin), S-2251 (plasmin), S-2302 (kallikrein) and S-2444 (urokinase) were substrates while S-2288 (broad range of serine proteinases including thrombin) was not hydrolyzed. Among a range of inhibitors Hg+2, aminophenylmercuriacetate, leupeptin, antipain and E-64 but not N-ethylmaleimide or iodoacetate abolished the activity of the purified isozymes against S-2444. Phenylmethylsulfonyl fluoride, soybean trypsin inhibitor and aprotinin were less effective. The presence of the classic catalytic triad (histidine-41, aspartate-86 and serine-189) suggests that Achelases I and II may be serine proteinases, but with a potentially free cysteine-185 which could react with thiol proteinase-directed reagents.

Original languageEnglish
Pages (from-to)214-221
Number of pages8
JournalBBA - Protein Structure
Issue number2
StatePublished - Aug 30 1991


  • Affinity chromatography
  • Chromogenic substrate
  • Metal chelate chromatography
  • Proteinase inhibitor

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology


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