Mutations to alter Aspergillus awamori glucoamylase selectivity. IV. Combinations of Asn20 -> Cys/Ala27 -> Cys, Ser30 -> Pro, Gly137 -> Ala, 311-314 loop, Ser411 -> Ala and Ser436 -> Pro

Six previously constructed and nine newly constructed Aspergillus awamori g lucoamylases with multiple mutations made by combining existing single muta tions were tested for their ability to produce glucose from maltodextrins. Multiple mutations have cumulative effects on glucose yield, specific activ ity and thermostability. No general correlation between glucose yield and t hermostability was observed, although mutations that presumably impede unfo lding at high temperatures uniformly increase thermostability and generally increase glucose yield. Peak glucose yields decrease with increasing tempe rature. The best combination of high glucose yield, high specific activity and high thermostability occurs in Asn20-->Cys/Ala27-->Cys/Ser30-->Pro/Gly1 37-->Ala glucoamylase.