The original paper wants the buffer to be filter sterilized. I am not sure if PIPES isn't heatstable (as HEPES or MOPS). But since the structure of HEPES and PIPES is rather similiar, I wouldn't autoclave it.

Autoclaving will change the pH of your buffer.. maintain sterility and try using sterile components.

I am not sure about the Inoue buffer but PIPES can be autoclaved as mentioned in the product information data sheet provided by sigma.

http://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Product_Information_Sheet/1/p6757pis.pdf