Camel kidney ferritin: Isolation and partial characterization

Camel kidney ferritin was isolated from a tissue homogenate by thermal dena turation, ammonium sulphate fractionation, Sephacryl S-300 gel filtration a nd DEAE-blue gel affinity chromatography. The yield and the iron and neutra l carbohydrate contents were 0.012 mg/g wet tissue, 4.0% and 2.7%, respecti vely. The phosphate:iron ratio was 0.13, twofold lower than that reported f or camel liver ferritin. Native gel electrophoresis revealed the presence o f a monomeric ferritin. SDS gel electrophoresis and immunoblotting showed t wo types of subunits, heavy and light, contrary to the extensive heterogene ity observed in camel liver ferritin. In general, the tissue ferritins shar ed a similar amino acid composition. However, a twofold lower glycine and a n eightfold higher arginine content were recorded for camel kidney ferritin . In addition, kidney ferritin had a relatively high content of glutamic ac id. Cross-reactivity studies by Ouchterlony double diffusion and noncompeti tive indirect ELISA revealed a distinct cross-reactivity between buffalo fe rritin antiserum and camel liver ferritin, but camel liver ferritin showed only weak cross-reactivity.