The use of isoelectric focusing to identify rhinoceros keratins

Keratins represent the principal structural proteins of hair. They are also found in horn, nail, claw, hoof, and feather. Hair and nail samples from human and canine sources and hair samples from mule deer, white tail deer, cat, moose, elk, antelope, caribou, raccoon, and goat were studied. Parrot and goose feathers were also analyzed. Keratins are polymorphic, and species differences are known to exist. Proteinaceous extracts of deer and antelope antlers and bovine and rhinoceros horn were prepared by solubilizing 10 mg of horn sample in 200 microL of a solution containing 12M urea, 74mM Trizma base, and 78mM dithiothreitol (DTT). Extraction took place over a 48-h period. A 25-microL aliquot of extract was removed and incubated with 5 microL of 0.1 M DTT for 10 min at 25 degrees C. Keratins were then separated by isoelectric focusing (IEF) on 5.2% polyacrylamide gels for 3 h and visualized using silver staining. At least 20 bands could be observed for each species studied. However, band patterns differed in the position of each band, in the number of bands, and in band coloration resulting from the silver staining process. Horn from two species of rhinoceros was examined. For both specimens, most bands occurred in the pH range of 4 to 5. Although similar patterns for both species were observed, they differed sufficiently to differentiate one from the other. As might be expected, the closer two species are related phylogenetically, the greater the similarity in the IEF pattern produced from their solubilized keratin.(ABSTRACT TRUNCATED AT 250 WORDS)