>1k73C (C:) observed residues (from ATOM records)
grriqgqrrgrgtstfrapshrykadlehrkvedgdviagtvvdiehdparsapvaavef
edgdrrlilapegvgvgdelqvgvdaeiapgntlplaeipegvpvcnvesspgdggkfar
asgvnaqllthdrnvavvklpsgemkrldpqcratigvvggggrtdkpfvkagnkhhkmk
argtkwpnvrgvamnavdhpfggggrqhpgkpksisrnappgrkvgdiaskrtgrgg