title: The molecular basis of the effect of temperature on enzyme activity

authors: Daniel, Roy M.

subjects: adaptation

abstract: Experimental data show that the effect of temperature on enzymes cannot be adequately explained in terms of a two-state model based on increases in activity and denaturation. The Equilibrium Model provides a quantitative explanation of enzyme thermal behaviour under reaction conditions by introducing an inactive (but not denatured) intermediate in rapid equilibrium with the active form. The temperature midpoint (Teq) of the rapid equilibration between the two forms is related to the growth temperature of the organism, and the enthalpy of the equilibrium (ΔHeq) to its ability to function over various temperature ranges. In the present study, we show that the difference between the active and inactive forms is at the enzyme active site. The results reveal an apparently universal mechanism, independent of enzyme reaction or structure, based at or near the active site, by which enzymes lose activity as temperature rises, as opposed to denaturation which is global. Results show that activity losses below Teq may lead to significant errors in the determination of ΔG*cat made on the basis of the twostate (‘Classical’) model, and the measured kcat will then not be a true indication of an enzyme’s catalytic power. Overall, the results provide a molecular rationale for observations that the active site tends to be more flexible than the enzyme as a whole, and that activity losses precede denaturation, and provide a general explanation in molecular terms for the effect of temperature on enzyme activity.

text: The molecular basis of the effect of temperature on enzyme activity Experimental data show that the effect of temperature on enzymes cannot be adequately explained in terms of a two-state model based on increases in activity and denaturation. The Equilibrium Model provides a quantitative explanation of enzyme thermal behaviour under reaction conditions by introducing an inactive (but not denatured) intermediate in rapid equilibrium with the active form. The temperature midpoint (Teq) of the rapid equilibration between the two forms is related to the growth temperature of the organism, and the enthalpy of the equilibrium (ΔHeq) to its ability to function over various temperature ranges. In the present study, we show that the difference between the active and inactive forms is at the enzyme active site. The results reveal an apparently universal mechanism, independent of enzyme reaction or structure, based at or near the active site, by which enzymes lose activity as temperature rises, as opposed to denaturation which is global. Results show that activity losses below Teq may lead to significant errors in the determination of ΔG*cat made on the basis of the twostate (‘Classical’) model, and the measured kcat will then not be a true indication of an enzyme’s catalytic power. Overall, the results provide a molecular rationale for observations that the active site tends to be more flexible than the enzyme as a whole, and that activity losses precede denaturation, and provide a general explanation in molecular terms for the effect of temperature on enzyme activity.

year: 2010

title: Equity: Kennedy v Boyle

authors: Chevalier-Watts, Juliet

abstract: The actions that led to this particular case hit the national headlines, and its resulting judgment has been subject to much scrutiny (see for example M B Rodriguez Ferrez “School Disciplinary Decisions, Judicial Review and Interim Relief” NZLJ June 2015 178-181), so commentary on this case in relation to the issue of interim injunctions is undoubtedly of interest. 
The background to this case is that 10 students of St Bede’s College, Christchurch, were selected to compete in the Maadi Cup, a national rowing regatta, at Lake Karapiro in the Waikato. At Auckland airport, two students, Jack Bell and Jordan Kennedy, rode, without authorisation, on the baggage carousel in to the secure baggage area. The boys were spoken to by the police and security offices, with no further action being taken. The Rector of the College, Justin Boyle, decided to suspend the two boys, and required them to return to Christchurch. This prevented the boys from being considered for selection in trials for the national rowing team.

text: Equity: Kennedy v Boyle The actions that led to this particular case hit the national headlines, and its resulting judgment has been subject to much scrutiny (see for example M B Rodriguez Ferrez “School Disciplinary Decisions, Judicial Review and Interim Relief” NZLJ June 2015 178-181), so commentary on this case in relation to the issue of interim injunctions is undoubtedly of interest. 
The background to this case is that 10 students of St Bede’s College, Christchurch, were selected to compete in the Maadi Cup, a national rowing regatta, at Lake Karapiro in the Waikato. At Auckland airport, two students, Jack Bell and Jordan Kennedy, rode, without authorisation, on the baggage carousel in to the secure baggage area. The boys were spoken to by the police and security offices, with no further action being taken. The Rector of the College, Justin Boyle, decided to suspend the two boys, and required them to return to Christchurch. This prevented the boys from being considered for selection in trials for the national rowing team.

year: 2015

title: Is there evidence that traditional mōteatea (Māori laments) were composed from a common stock of oral formulae?

authors: Roa, Raukura

subjects: New Zealand

abstract: Oral formulaic composition, which involves the use of communally owned formulae of various kinds, is a common feature of verbal arts produced in many different languages. It is particularly associated with pre-literate cultures and tends to be gradually replaced by more individualistic verbal art forms when societies become literate. There are very few publications in which the analysis of mōteatea (Māori laments) is linked explicitly to oral formulaic theory. Nevertheless, there is sufficient evidence in published sources to indicate that traditional mōteatea (defined here as mōteatea that are not fundamentally influenced by European cultural beliefs and practices) exhibit evidence of regularly recurring, conventional themes (such as death, separation, loss and travel) and motifs (such as the setting sun, the presence of rain or mist and sleeplessness). The research reported here set out to test the hypothesis that traditional mōteatea were made up of verbal formulae, that is, of the same or very similar groups of words derived from a common store of poetic resources. Based on the analysis of the mōteatea included in Ngā mōteatea, a collection initially established by Sir Apirana Ngata, I conclude that this hypothesis must be rejected.

text: Is there evidence that traditional mōteatea (Māori laments) were composed from a common stock of oral formulae? Oral formulaic composition, which involves the use of communally owned formulae of various kinds, is a common feature of verbal arts produced in many different languages. It is particularly associated with pre-literate cultures and tends to be gradually replaced by more individualistic verbal art forms when societies become literate. There are very few publications in which the analysis of mōteatea (Māori laments) is linked explicitly to oral formulaic theory. Nevertheless, there is sufficient evidence in published sources to indicate that traditional mōteatea (defined here as mōteatea that are not fundamentally influenced by European cultural beliefs and practices) exhibit evidence of regularly recurring, conventional themes (such as death, separation, loss and travel) and motifs (such as the setting sun, the presence of rain or mist and sleeplessness). The research reported here set out to test the hypothesis that traditional mōteatea were made up of verbal formulae, that is, of the same or very similar groups of words derived from a common store of poetic resources. Based on the analysis of the mōteatea included in Ngā mōteatea, a collection initially established by Sir Apirana Ngata, I conclude that this hypothesis must be rejected.

year: 2007