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At least 919 records · Page 51Linked to original sources
PubMed1993

The immunogenicity of hookworm (Necator americanus) acetylcholinesterase (AChE) in man.

A number of different but complementary approaches have been used to demonstrate the immunogenicity of Necator americanus acetylcholinesterase to infected individuals. Western blotting of parasite somatic extracts with human post-infection sera and a specific rabbit antiserum to AChE resulted in the development of almost identical antigen-recognition profiles. AChE-containing fractions produced by preparative iso-electric focusing were subsequently shown to be antigenic in ELISA using post-infection sera. This preliminary data was reinforced by the affinity purification of AChE by immobilized post-infection IgG, and the immunoprecipitation of AChE activity from ES by post-infection IgG. Finally, AChE purified by affinity chromatography on edrophonium chloride was shown to be antigenic by Western blotting, and in ELISA, against post-infection sera, although a degree of re-activity was also seen with normal human sera. This data is discussed in the context of the host-parasite relationship.

Acetylcholinesterase↗
PubMed2003

Molecular cloning of a novel multidomain Kunitz-type proteinase inhibitor from the hookworm Ancylostoma caninum.

Degenerate oligonucleotide primers derived from conserved serine protease inhibitors were used to amplify a 90-base pair (bp) amplicon from an Ancylostoma caninum adult-stage complementary deoxyribonucleic acid (cDNA) library by polymerase chain reaction (PCR). The amplicon was labeled and used as a probe to screen the library, and a 2,300-bp cDNA clone was identified. The 5' end of the molecule was obtained from adult cDNA by 5'-RACE. The complete sequence named A. caninum Kunitz-type protease inhibitor (Ac-kpi-1) was 2,371 bp and encoded a 759-amino acid open reading frame. The deduced amino acid sequence had a calculated molecular weight of 84,886 Da and contained an amino terminal signal peptide, suggesting that the protein is secreted. Analysis of the predicted protein sequence indicates 12 highly conserved Kunitz-type serine protease inhibitor domains connected by short, conserved spacers. On the basis of sequence analysis, the first 11 domains are predicted to be active serine protease inhibitors based on the P1 amino acid. Domains 5-8 have identical amino acid sequences, and the remaining domains are 38-88% identical. Domain 12 lacks several of the conserved cysteine residues and has an atypical amino acid in the P1 position, suggesting that it is nonfunctional. Reverse transcriptase-PCR indicated that the Ac-kpi-1 messenger ribonucleic acid is present in egg, L1, L3, and adult stages but is most abundant in the adult stage. Ac-KPI-1 is most similar in domain architecture to several extracellular matrix proteins involved in cellular remodeling during insect development. In addition, there are 44 nematode proteins containing one or more Kunitz domains in GenBank, including several with multiple domains.

Amino Acid Sequence↗
PubMed1999

Necator americanus (human hookworm) aspartyl proteinases and digestion of skin macromolecules during skin penetration.

The infective larvae of Necator americanus were shown to secrete all mechanistic classes of proteolytic enzymes with two overall pH optima of 6.5 and 8.5 using fluorescein isothiocyanate-labeled casein as the substrate. Since infective larvae are obligate skin penetrators, the effect of each of these enzyme classes against macromolecules derived from human skin was examined. Larval secretions were shown to degrade collagen types I, III, IV, and V, fibronectin, laminin, and elastin. All the skin macromolecules tested were hydrolyzed by aspartyl proteinase activity, which was inhibitable by pepstatin A. Collagen and elastin was also hydrolyzed by metalloproteinase activity, while the serine proteinase activity hydrolyzed only elastin. As a consequence of these experiments, the effect of proteinase inhibitors on the penetration of live larvae through hamster skin was tested. Larval penetration was significantly inhibited only by pepstatin A, confirming the importance of the aspartyl proteinase activity during the skin penetration process.

Animals↗