| Popis: |
In the active site of E. coli phosphofructokinase, Asp 103 which binds the magnesium ion has been replaced by asparagine. The Asp l03 Asn mutation has a limited effect on t11e affinities for the substrates, the catalytic rate-constants in both directions, and the allosteric regulation of the physiological and reverse reactions. This mutation significantly decreases the pK of an ionizable group that controls the pH-profile of kcat. by 0.7 to 0.8 pH unit for the physiological reaction, and by 1.3 pl-lunit or more for the reverse reaction. |
