Tyrosine-derived cross-linking amino acids in the sheath of Haemonchus contortus infective larvae.
The sheath or second-molt cuticle (2M) was isolated from in vitro exsheathed Haemonchus contortus infective larvae (L3[2M]). Acid hydrolysates of 2-mercaptoethanol (2ME)-soluble and 2ME-insoluble cuticular proteins were analyzed by high performance liquid chromatography for tyrosine-derived cross-linking amino acids. Dityrosine and isotrityrosine were identified by their chromatographic behavior, absorbance spectra, and other chemical characteristics in both the 2ME-soluble and 2ME-insoluble fractions. Dityrosine and isotrityrosine were found in greater amounts in the 2ME-insoluble proteins. When intact 2M cuticles were labeled with 125I prior to acid hydrolysis, radiolabel was recovered in tyrosine but not dityrosine or isotrityrosine indicating that the tyrosine cross-links are not susceptible to iodination in the intact protein. The results are consistent with a hypothesis that tyrosine-derived cross-links are important components of H. contortus 2M cuticular proteins.
Helminthic Diseases Laboratory, Livestock and Poultry Sciences Institute, United States Department of Agriculture, Beltsville, Maryland 20705.
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D000818:Animals; D002851:Chromatography, High Pressure Liquid; D006189:Haemonchus / Q000032:analysis*; D015801:Helminth Proteins / Q000032:analysis*; D006868:Hydrolysis; D007814:Larva / Q000032:analysis; D015394:Molecular Structure; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000032:analysis / Q000302:isolation & purification
D015801:Helminth Proteins; D014443:Tyrosine; C030231:isotrityrosine; C007543:dityrosine