Abstract: Disclosed is a protein glutaminase having improved thermotolerance. A protein glutaminase comprising a polypeptide indicated in any among (1) to (3) has improved thermotolerance. (1) A polypeptide comprising a SEQ ID NO: 1 or 2 amino acid sequence; (2) a polypeptide wherein one or more amino acid residues are substituted, added, inserted or lost in the amino acid sequence indicated by SEQ ID NO: 1 or 2 and exhibiting the same thermotolerance as the amino acid sequence indicated by SEQ ID NO: 1 or 2: and (3) a polypeptide having at least 76% sequence identity with the amino acid sequence indicated by SEQ ID NO: 1 or 2 and having similar thermotolerance to a polypeptide comprising the amino acid sequence indicated by SEQ ID NO: 1 or 2.

Abstract: This invention provides a method for producing allulose using an allulose-producing enzyme having high pH stability in a low-pH region. The method comprises a step of allowing a polypeptide consisting of the amino acid sequence shown in SEQ ID NO: 6 or a polypeptide consisting of a sequence having 90% or higher identity to the amino acid sequence shown in SEQ ID NO: 6 and capable of producing allulose to react with fructose under acidic conditions in which pH is less than 6.

Abstract: The object of the present invention is to provide highly safe collagenase that is useful for food or medical use, and the use thereof. Provided is an enzyme agent comprising, as an active ingredient, collagenase having an amino acid sequence having an identity of 90% or more to the amino acid sequence as set forth in SEQ ID NO: 1. This enzyme agent is useful for production of a collagen tripeptide or tenderization of edible meat.