title: Tests of predictions made by the Equilibrium Model for the effect of temperature on enzyme activity

authors: Oudshoorn, Matthew Leslie

subjects: enzymes

abstract: The Classical Model describing the effects of temperature on enzyme activity consists of two processes: the catalytic reaction defined by ΔG cat and irreversible inactivation defined by ΔG inact, this model however, does not account for the observed temperature- dependant behaviour of enzymes. The recent development of the Equilibrium Model is governed not only by ΔG cat and ΔG inact but also by two new intrinsic parameters ΔHeq and Teq, which describe the enthalpy and the temperature of the midpoint, respectively, of a active and reversibly inactive enzyme transition. Teq is central to the physiological adaptation of an enzyme to its environmental temperature and links the molecular, physiological and environmental aspects of life to temperature in a way that has not been previously possible. The Equilibrium Model is therefore a more complete and accurate description of the effects of temperature on enzymes, it has provided new tools for describing and investigating enzyme thermal adaptation and possibly new biotechnological tools.

The effects of the incorporating in the new Model of the parameters Teq and ΔH eq yield major differences from the Classical Model, with simulated data calculated according to the Equilibrium Model fitting well to experimental data and showing an initial rate temperature optimum that is independent of assay duration. Simulated data simulated according to the Classical Model can not be fitted to experimental data. All enzymes so far studied (gt30) display behaviour predicted by the Equilibrium Model.

The research described here has set out to: experimentally test observations made by Eisenthal et al., on the basis of enzyme reactor data simulated according to the Equilibrium Model; to test the Equilibrium Model using an unusual (rapidly renaturable) enzyme, RNAase; and to test the proposed molecular basis of the Equilibrium Model by examining the effect of a change at the enzymes active site.

The experimental results gathered here on the effect of time and temperature on enzyme reactor output confirm the predictions made by Eisenthal et al. (2006) and indicate that the Equilibrium Model can be a useful aid in predicting reactor performance. The Equilibrium Model depends upon the acquisition of data on the variation of the Vmax of an enzyme with time and temperature, and the non-ideal behaviour of RNase A made it impossible to collect such data for this enzyme, as a result the Equilibrium Model could not be applied. The disulfide bond within the active site cleft of A.k 1 protease was cleaved as a probe of the mechanism of the Equilibrium Model, which is proposed to arise from molecular changes at the enzymes active site. Support for the proposed mechanism was gained through the comparison of experimentally determined temperature dependence of the native and reduced forms of the enzyme and application of this data to the Equilibrium Model.

text: Tests of predictions made by the Equilibrium Model for the effect of temperature on enzyme activity The Classical Model describing the effects of temperature on enzyme activity consists of two processes: the catalytic reaction defined by ΔG cat and irreversible inactivation defined by ΔG inact, this model however, does not account for the observed temperature- dependant behaviour of enzymes. The recent development of the Equilibrium Model is governed not only by ΔG cat and ΔG inact but also by two new intrinsic parameters ΔHeq and Teq, which describe the enthalpy and the temperature of the midpoint, respectively, of a active and reversibly inactive enzyme transition. Teq is central to the physiological adaptation of an enzyme to its environmental temperature and links the molecular, physiological and environmental aspects of life to temperature in a way that has not been previously possible. The Equilibrium Model is therefore a more complete and accurate description of the effects of temperature on enzymes, it has provided new tools for describing and investigating enzyme thermal adaptation and possibly new biotechnological tools.

The effects of the incorporating in the new Model of the parameters Teq and ΔH eq yield major differences from the Classical Model, with simulated data calculated according to the Equilibrium Model fitting well to experimental data and showing an initial rate temperature optimum that is independent of assay duration. Simulated data simulated according to the Classical Model can not be fitted to experimental data. All enzymes so far studied (gt30) display behaviour predicted by the Equilibrium Model.

The research described here has set out to: experimentally test observations made by Eisenthal et al., on the basis of enzyme reactor data simulated according to the Equilibrium Model; to test the Equilibrium Model using an unusual (rapidly renaturable) enzyme, RNAase; and to test the proposed molecular basis of the Equilibrium Model by examining the effect of a change at the enzymes active site.

The experimental results gathered here on the effect of time and temperature on enzyme reactor output confirm the predictions made by Eisenthal et al. (2006) and indicate that the Equilibrium Model can be a useful aid in predicting reactor performance. The Equilibrium Model depends upon the acquisition of data on the variation of the Vmax of an enzyme with time and temperature, and the non-ideal behaviour of RNase A made it impossible to collect such data for this enzyme, as a result the Equilibrium Model could not be applied. The disulfide bond within the active site cleft of A.k 1 protease was cleaved as a probe of the mechanism of the Equilibrium Model, which is proposed to arise from molecular changes at the enzymes active site. Support for the proposed mechanism was gained through the comparison of experimentally determined temperature dependence of the native and reduced forms of the enzyme and application of this data to the Equilibrium Model.

year: 2008

title: Police education and democratic policing in Taiwan: a longitudinal quasi-experimental study of the effects of selection and police socialisation on human rights, moral reasoning and prejudice

authors: Lin, Keng‑hui

abstract: Objectives: To investigate the effects of selection and group socialisation on support of human rights, moral reasoning and prejudice in police officers in Taiwan. Methods: We used a longitudinal quasi-experimental design to track three cohorts of police officers (n = 585) and a comparison group of criminology undergraduates (n = 43). Results: There were no statistically significant differences in measures of human rights, moral reasoning and prejudice between new police recruits and the control group. However, time in police education was associated with a statistically significant reduction in police officer support of human rights, moral reasoning and an increase in prejudice. In the control group, the reverse was true. Conclusions: Exposure to police education in Taiwan resulted in police officers being significantly more prejudiced and significantly less adherent to the principles of human rights and moral reasoning. These results appear to be attributable to police socialisation rather than selection effects.

text: Police education and democratic policing in Taiwan: a longitudinal quasi-experimental study of the effects of selection and police socialisation on human rights, moral reasoning and prejudice Objectives: To investigate the effects of selection and group socialisation on support of human rights, moral reasoning and prejudice in police officers in Taiwan. Methods: We used a longitudinal quasi-experimental design to track three cohorts of police officers (n = 585) and a comparison group of criminology undergraduates (n = 43). Results: There were no statistically significant differences in measures of human rights, moral reasoning and prejudice between new police recruits and the control group. However, time in police education was associated with a statistically significant reduction in police officer support of human rights, moral reasoning and an increase in prejudice. In the control group, the reverse was true. Conclusions: Exposure to police education in Taiwan resulted in police officers being significantly more prejudiced and significantly less adherent to the principles of human rights and moral reasoning. These results appear to be attributable to police socialisation rather than selection effects.

year: 2023

title: Whiti te rā: A guide to connecting Māori to traditional wellbeing pathways.

authors: McLachlan, Andre David

abstract: Māori health models, introduced in the 1980s, brought needed cultural worldviews to an otherwise monocultural health system. However, minimal changes have occurred. In mainstream practice, deeper cultural understandings and action-orientations of these models can be overlooked, to the detriment of Māori wellbeing.
In particular, Māori cultural concepts such as mauri ora (an active state of wellbeing) and a secure cultural identity are notable core wellbeing pathways that need further exploration. Using a systematic narrative literature review, 36 papers identified pathways that used core cultural activities for Māori wellbeing. A thematic analysis produced six themes or pathways towards wellbeing for Māori – te reo Māori: Māori language, taiao: connection with the environment, wairua: Māori spiritual beliefs and practices, mahi-a-toi:
Māori expressive art forms, take pū whānau: Māori relational values, and whakapapa: intergenerational relationships. Forty experienced Māori psychologists analysed the themes and offered expert examples practice pathways for Māori wellbeing. The six themes and feedback is presented in a visual image Whiti Te Rā with instructions for Māori practitioners to guide whai ora Māori (Māori clients) to explore their level of knowledge and comfort, and active engagement with Māori pathways to wellbeing. The model has potential for mental health policy, future research, curriculum development, and synthesising Māori knowledge towards wellbeing pathways.

text: Whiti te rā: A guide to connecting Māori to traditional wellbeing pathways. Māori health models, introduced in the 1980s, brought needed cultural worldviews to an otherwise monocultural health system. However, minimal changes have occurred. In mainstream practice, deeper cultural understandings and action-orientations of these models can be overlooked, to the detriment of Māori wellbeing.
In particular, Māori cultural concepts such as mauri ora (an active state of wellbeing) and a secure cultural identity are notable core wellbeing pathways that need further exploration. Using a systematic narrative literature review, 36 papers identified pathways that used core cultural activities for Māori wellbeing. A thematic analysis produced six themes or pathways towards wellbeing for Māori – te reo Māori: Māori language, taiao: connection with the environment, wairua: Māori spiritual beliefs and practices, mahi-a-toi:
Māori expressive art forms, take pū whānau: Māori relational values, and whakapapa: intergenerational relationships. Forty experienced Māori psychologists analysed the themes and offered expert examples practice pathways for Māori wellbeing. The six themes and feedback is presented in a visual image Whiti Te Rā with instructions for Māori practitioners to guide whai ora Māori (Māori clients) to explore their level of knowledge and comfort, and active engagement with Māori pathways to wellbeing. The model has potential for mental health policy, future research, curriculum development, and synthesising Māori knowledge towards wellbeing pathways.

year: 2021