Patent ID: 7915022

Claim:
An isolated polypeptide selected from the group consisting of: (a) a polypeptide comprising the amino acid sequence of SEQ ID NO: 4, and (b) a polypeptide having the amino acid sequence of SEQ ID NO: 4 except for at least one modification in SEQ ID NO: 4 selected from the group consisting of: (1) the alanine at position 42 of SEQ ID NO: 4 is substituted by glycine, (2) the glutamic acid at position 43 of SEQ ID NO: 4 is substituted by alanine, (3) the lysine at position 46 of SEQ ID NO: 4 is substituted by glutamic acid, and (4) the asparagine at position 49 of SEQ ID NO: 4 is substituted by lysine.