title: Dynamics of immobilized and native Escherichia coli dihydrofolate reductase by quasielastic neutron scattering

authors: Tehei, Moeava

abstract: The internal dynamics of native and immobilized Escherichia coli dihydrofolate reductase (DHFR) have been examined using incoherent quasielastic neutron scattering. These results reveal no difference between the high frequency vibration mean-square displacement of the native and the immobilized E. coli DHFR. However, length-scale-dependent, picosecond dynamical changes are found. On longer length scales, the dynamics are comparable for both DHFR samples. On shorter length scales, the dynamics is dominated by local jump motions over potential barriers. The residence time for the protons to stay in a potential well is  = 7.95 ± 1.02 ps for the native DHFR and  = 20.36 ± 1.80 ps for the immobilized DHFR. The average height of the potential barrier to the local motions is increased in the immobilized DHFR, and may increase the activation energy for the activity reaction, decreasing the rate as observed experimentally. These results suggest that the local motions on the picosecond timescale may act as a lubricant for those associated with DHFR activity occurring on a slower millisecond timescale. Experiments indicate a significantly slower catalytic reaction rate for the immobilized E. coli DHFR. However, the immobilization of the DHFR is on the exterior of the enzyme and essentially distal to the active site, thus this phenomenon has broad implications for the action of drugs distal to the active site.

text: Dynamics of immobilized and native Escherichia coli dihydrofolate reductase by quasielastic neutron scattering The internal dynamics of native and immobilized Escherichia coli dihydrofolate reductase (DHFR) have been examined using incoherent quasielastic neutron scattering. These results reveal no difference between the high frequency vibration mean-square displacement of the native and the immobilized E. coli DHFR. However, length-scale-dependent, picosecond dynamical changes are found. On longer length scales, the dynamics are comparable for both DHFR samples. On shorter length scales, the dynamics is dominated by local jump motions over potential barriers. The residence time for the protons to stay in a potential well is  = 7.95 ± 1.02 ps for the native DHFR and  = 20.36 ± 1.80 ps for the immobilized DHFR. The average height of the potential barrier to the local motions is increased in the immobilized DHFR, and may increase the activation energy for the activity reaction, decreasing the rate as observed experimentally. These results suggest that the local motions on the picosecond timescale may act as a lubricant for those associated with DHFR activity occurring on a slower millisecond timescale. Experiments indicate a significantly slower catalytic reaction rate for the immobilized E. coli DHFR. However, the immobilization of the DHFR is on the exterior of the enzyme and essentially distal to the active site, thus this phenomenon has broad implications for the action of drugs distal to the active site.

year: 2006-10

title: The audacity of Trump: How he won and what we missed

authors: Steff, Reuben

abstract: Donald Trump made a number of key strategic decisions during his election campaign. Contrary to the common view that his campaign was marked by incompetence and dysfunction, there is considerable evidence that he made adroit decisions at key times. These were overlooked and dismissed by his political opponents to their ultimate disadvantage and defeat. If the Democratic Party hopes to take back the White House in four years' time, and the wider world wants to understand the 'Trump phenomenon', it is imperative that we look at the logical thread that underlies Trump's seemingly irrational behaviour.

text: The audacity of Trump: How he won and what we missed Donald Trump made a number of key strategic decisions during his election campaign. Contrary to the common view that his campaign was marked by incompetence and dysfunction, there is considerable evidence that he made adroit decisions at key times. These were overlooked and dismissed by his political opponents to their ultimate disadvantage and defeat. If the Democratic Party hopes to take back the White House in four years' time, and the wider world wants to understand the 'Trump phenomenon', it is imperative that we look at the logical thread that underlies Trump's seemingly irrational behaviour.

year: 2017

title: E Ara Apanui

authors: Maxwell, Te Kahautu

abstract: E Ara Apanui recites the genealogical links between the Te Whakatōhea iwi and the host people of the Te Whānau a Apanui iwi. This new composition was performed by Ōpōtiki Mai Tawhiti at the Mātaatua Regional Kapa Haka Competition to qualify for Te Matatini 2013.

text: E Ara Apanui E Ara Apanui recites the genealogical links between the Te Whakatōhea iwi and the host people of the Te Whānau a Apanui iwi. This new composition was performed by Ōpōtiki Mai Tawhiti at the Mātaatua Regional Kapa Haka Competition to qualify for Te Matatini 2013.

year: 2012