Abstract: A method for cleaving polypeptides includes contacting a polypeptide with a recombinant or isolated Kell protein having proteolytic activity for the polypeptide. A method for converting big endothelins-1, -2 and -3 to endothelins-1, -2 and -3 respectively comprises contacting the big endothelin with Kell protein having proteolytic activity for cleaving big endothelin-1, -2 and -3 to endothelin-1, -2 or -3 respectively. In another embodiment, the Kell protein cleaves vasoactive intestinal peptide.

Abstract: The invention provides a diagnostic method of determining Kell genotype by the identification of the molecular basis of a Kell polymorphism. Specifically, the invention provides a method for determining K1/K2 genotype with great accuracy, overcoming problems associated with traditional serological typing methods. The diagnostic method of the invention preferably employs amplification of K1/K2 nucleic acid sequences, and optionally employs differential cleavage of K1- and K2-specific nucleic acid sequences by a restriction enzyme. Also provided are nucleic acid oligomers useful as probes or primers for the method of the invention. Furthermore, diagnostic kits for the determination of Kell genotype are provided.

Abstract: The invention provides a diagnostic method of determining Kell genotype by the identification of the molecular basis of a Kell polymorphism. Specifically, the invention provides a method for determining K1/K2 genotype with great accuracy, overcoming problems associated with traditional serological typing methods. The diagnostic method of the invention preferably employs amplification of K1/K2 nucleic acid sequences, and optionally employs differential cleavage of K1- and K2-specific nucleic acid sequences by a restriction enzyme. Also provided are nucleic acid oligomers useful as probes or primers for the method of the invention. Furthermore, diagnostic kits for the determination of Kell genotype are provided.