DNA and recombinant DNA that encode a peptide-forming enzyme, a method for producing a peptide-forming enzyme, and a method for producing a dipeptide are disclosed. In the preferred embodiment, the headrest is inclinably supported by the backrest, and a projecting part turning above is provide for compensating an estrangement between the headrest and the backrest. The control parameters are tuned using a prediction error filter, the prediction error filter selecting values of the control parameters that minimize the values of a prediction error between actual and predicted values of an autoregressive process. The portion contacted by the protrusion 10 is a portion, on the inside of the plaster body 5, that excludes an outer periphery of the plaster body 5. This approach provides several significant advantages.