Inverse heavy enzyme isotope effects in methylthioadenosine nucleosidases.

ABSTRACT: Heavy enzyme isotope effects occur in proteins substituted with ²H-, ¹³C-, and ¹⁵N-enriched amino acids. Mass alterations perturb femtosecond protein motions and have been used to study the linkage between fast motions and transition-state barrier crossing. Heavy enzymes typically show slower rates for their chemical steps. Heavy bacterial methylthioadenosine nucleosidases (MTANs from Helicobactor pylori and Escherichia coli) gave normal isotope effects in steady-state kinetics, with slower rates for the heavy enzymes. However, both enzymes revealed rare inverse isotope effects on their chemical steps, with faster chemical steps in the heavy enzymes. Computational transition-path sampling studies of H. pylori and E. coli MTANs in

SUBMITTER: Brown M 

PROVIDER: S-EPMC8501826 | biostudies-literature | 2021 Oct

REPOSITORIES: biostudies-literature