Polypeptides, and methods for their use, are disclosed that have an amino acid sequence at least 75% identical to the amino acid sequence of SEQ ID NO: 1, are provided, wherein (a) the polypeptide degrades a PFQPQLPY (SEQ ID NO: 140) peptide and/or a PFPQPQQPF (SEQ ID NO: 68) at pH 4; (b) residue 467 is Ser, residue 267 is Glu, and residue 271 is Asp; and (c) the polypeptide comprises an amino acid change from SEQ ID NO: 1 at one or more residues selected from the group consisting of 221, 262E, 268, 269, 270, 319A, 320, 354E/Q/R/Y, 358S/Q/T, 368F/Q, 399, 402, 406, 424, 449, 461, 463, 105, 171, 172, 173, 174, and 456.