Abstract: Provided is a zwitterionic polymer that has a zwitterion that includes an effect of improving the stability of proteins. This zwitterionic polymer is a polymeric protein stabilizer that exhibits a protein stabilizing effect even at a small addition amount of addition, and at the same time has an antioxidant capability. Also provided is a method for producing this zwitterionic polymer. This problem is solved by a zwitterionic polymer containing a repeating unit represented by formula (1) and having a number-average molecular weight of 1,000 to 1,000,000. On formula (1), R1 and R2 are each independently selected from a hydrogen atom; linear, branched or cyclic alkyl groups having 1 to 6 carbons; aromatic groups having 6 to 20 carbons; or alkylene groups having 1 to 6 carbons and formed by linking R1 to R2. R3 represents a hydrogen atom or a methyl group).

Abstract: Provided is a zwitterionic polymer that has a zwitterion that includes an effect of improving the stability of proteins. This zwitterionic polymer is a polymeric protein stabilizer that exhibits a protein stabilizing effect even at a small addition amount of addition, and at the same time has an antioxidant capability. Also provided is a method for producing this zwitterionic polymer. This problem is solved by a zwitterionic polymer containing a repeating unit represented by formula (1) and having a number-average molecular weight of 1,000 to 1,000,000. On formula (1), R1 and R2 are each independently selected from a hydrogen atom; linear, branched or cyclic alkyl groups having 1 to 6 carbons; aromatic groups having 6 to 20 carbons; or alkylene groups having 1 to 6 carbons and formed by linking R1 to R2. R3 represents a hydrogen atom or a methyl group).

Abstract: A hetero type monodispersed polyethylene glycol containing a compound represented by the following formula (1): NH2—(CH2CH2O)a—CH2CH2COOH??(1) (in the formula (1), a represents an integer from 6 to 40); wherein any of (A) a chromatogram detected by a differential refractometer when the hetero type monodispersed polyethylene glycol is separated using reverse phase chromatography, (B) a chromatogram detected by a differential refractometer when the hetero type monodispersed polyethylene glycol is separated using cation exchange chromatography, and (C) a chromatogram detected by a differential refractometer when the hetero type monodispersed polyethylene glycol containing a compound represented by the formula (1) shown above is derivatized and separated using anion exchange chromatography satisfy specific relational expressions, respectively.

Abstract: A hetero type monodispersed polyethylene glycol containing a compound represented by the following formula (1): NH2—(CH2CH2O)a—CH2CH2COOH??(1) (in the formula (1), a represents an integer from 6 to 40); wherein any of (A) a chromatogram detected by a differential refractometer when the hetero type monodispersed polyethylene glycol is separated using reverse phase chromatography, (B) a chromatogram detected by a differential refractometer when the hetero type monodispersed polyethylene glycol is separated using cation exchange chromatography, and (C) a chromatogram detected by a differential refractometer when the hetero type monodispersed polyethylene glycol containing a compound represented by the formula (1) shown above is derivatized and separated using anion exchange chromatography satisfy specific relational expressions, respectively.