Open Access. Powered by Scholars. Published by Universities.®

Social and Behavioral Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Faculty of Science, Medicine and Health - Papers: part A

2005

Activity

Articles 1 - 2 of 2

Full-Text Articles in Social and Behavioral Sciences

Enzyme Activity And Flexibility At Very Low Hydration, V Kurkal, R M. Daniel, John L. Finney, Moeava Tehei, R V. Dunn, Jeremy C. Smith Jan 2005

Enzyme Activity And Flexibility At Very Low Hydration, V Kurkal, R M. Daniel, John L. Finney, Moeava Tehei, R V. Dunn, Jeremy C. Smith

Faculty of Science, Medicine and Health - Papers: part A

Recent measurements have demonstrated enzyme activity at hydrations as low as 3%. This raises the question of whether hydration-induced enzyme flexibility is important for activity. Here, to address this, picosecond dynamic neutron scattering experiments are performed on pig liver esterase powders at 0%, 3%, 12%, and 50% hydration by weight and at temperatures ranging from 120 to 300 K. At all temperatures and hydrations, significant quasielastic scattering intensity is found in the protein, indicating the presence of anharmonic, diffusive motion. As the hydration increases, a temperature-dependent dynamical transition appears and strengthens involving additional diffusive motion. The implication of these results ...


Replication Termination In Escherichia Coli: Structure And Anti-Helicase Activity Of The Tus-Ter Complex, Cameron Neylon, Andrew V. Kralicek, Thomas M. Hill, Nicholas E. Dixon Jan 2005

Replication Termination In Escherichia Coli: Structure And Anti-Helicase Activity Of The Tus-Ter Complex, Cameron Neylon, Andrew V. Kralicek, Thomas M. Hill, Nicholas E. Dixon

Faculty of Science, Medicine and Health - Papers: part A

The arrest of DNA replication in Escherichia coli is triggered by the encounter of a replisome with a Tus protein-Ter DNA complex. A replication fork can pass through a Tus-Ter complex when traveling in one direction but not the other, and the chromosomal Ter sites are oriented so replication forks can enter, but not exit, the terminus region. The Tus-Ter complex acts by blocking the action of the replicative DnaB helicase, but details of the mechanism are uncertain. One proposed mechanism involves a specific interaction between Tus-Ter and the helicase that prevents further DNA unwinding, while ...