title: Bioactive properties of proline-rich peptides derived from dairy milk and colostrum

authors: Tock, Adriënne

abstract: Dipeptidyl peptidase 4 (DPP4) is a serine exopeptidase that cleaves dipeptides from the N-terminus, preferably when proline occupies the penultimate position. This enzyme plays a key role in maintaining glucose homeostasis by degrading insulin secreting incretins, such as gastric inhibitory peptide and glucagon-like peptide 1, thereby reducing insulin secretion. Consequently, inhibiting DPP4 activity has become a major strategy for mitigating the effects of Type 2 diabetes mellitus. A functional food approach involves inhibiting this enzyme with DPP4-inhibiting peptides that are generated from dairy products. Milk and colostrum are associated with various health benefits, largely due to the presence of many bioactive peptides. A significant portion of these are proline-rich peptides (PRPs), some of which exhibit DPP4 inhibitory properties. While many DPP4-inhibitory dairy peptides have been identified or predicted through ‘in silico’ analysis, the variations across different species and between milk and colostrum have yet to be explored.   

This research identified new PRPs in cow, goat, sheep, and deer milk and colostrum and demonstrated that some of these peptides have DPP4-inhibitory activity. Peptide identification and characterisation were performed using liquid chromatography tandem mass spectrometry, a new resin-based DPP4-binding procedure, and in vitro DPP4 inhibition assays. PRPs represented 20-30% of the identified peptides within each sample, with sheep colostrum reaching 35%. Peptides from deer had the lowest alignment with the Cervidae proteome, likely due to database incompleteness. Exact peptide sequence overlap among all samples was minimal. Peptides were chosen for DPP4 inhibition assays based on the resin pull-down assay results, presence of proline in the penultimate position, abundance, length, and origin. Out of the 21 selected peptides, 14 showed over 50% inhibition at 250 µM. Interestingly, these peptides revealed that greater proline content did not reliably predict DPP4 inhibition, which is contradictory to reports in the literature. The top six DPP4-inhibiting peptides were selected for IC50 determination, with values ranging from 46.7 to 103.2 µM. Even though these peptides were all less potent than the reference peptide inhibitor Diprotin A (IC50 of 2.69 ± 1.09 µM, n = 6), they all showed high abundance of at least 105. Additionally, most peptides represented novel sequences that were not previously reported in the literature as DPP4-inhibiting peptides. Pooled peptide fractions from each sample did not show inhibition at the tested concentration, although permeate from a dairy plant showed 34.41% ± 8.27 (n = 3) DPP4 inhibition at only 1.5% w/w of the permeate concentration. AlphaFold 3 predictions revealed that these peptides and Diprotin A docked at similar positions within the DPP4 active site. These findings provide the basis for future studies on interspecies differences, application of novel binding assays to find DPP4 inhibitors, and further exploration of dairy peptides as potential DPP4 inhibitors.

text: Bioactive properties of proline-rich peptides derived from dairy milk and colostrum Dipeptidyl peptidase 4 (DPP4) is a serine exopeptidase that cleaves dipeptides from the N-terminus, preferably when proline occupies the penultimate position. This enzyme plays a key role in maintaining glucose homeostasis by degrading insulin secreting incretins, such as gastric inhibitory peptide and glucagon-like peptide 1, thereby reducing insulin secretion. Consequently, inhibiting DPP4 activity has become a major strategy for mitigating the effects of Type 2 diabetes mellitus. A functional food approach involves inhibiting this enzyme with DPP4-inhibiting peptides that are generated from dairy products. Milk and colostrum are associated with various health benefits, largely due to the presence of many bioactive peptides. A significant portion of these are proline-rich peptides (PRPs), some of which exhibit DPP4 inhibitory properties. While many DPP4-inhibitory dairy peptides have been identified or predicted through ‘in silico’ analysis, the variations across different species and between milk and colostrum have yet to be explored.   

This research identified new PRPs in cow, goat, sheep, and deer milk and colostrum and demonstrated that some of these peptides have DPP4-inhibitory activity. Peptide identification and characterisation were performed using liquid chromatography tandem mass spectrometry, a new resin-based DPP4-binding procedure, and in vitro DPP4 inhibition assays. PRPs represented 20-30% of the identified peptides within each sample, with sheep colostrum reaching 35%. Peptides from deer had the lowest alignment with the Cervidae proteome, likely due to database incompleteness. Exact peptide sequence overlap among all samples was minimal. Peptides were chosen for DPP4 inhibition assays based on the resin pull-down assay results, presence of proline in the penultimate position, abundance, length, and origin. Out of the 21 selected peptides, 14 showed over 50% inhibition at 250 µM. Interestingly, these peptides revealed that greater proline content did not reliably predict DPP4 inhibition, which is contradictory to reports in the literature. The top six DPP4-inhibiting peptides were selected for IC50 determination, with values ranging from 46.7 to 103.2 µM. Even though these peptides were all less potent than the reference peptide inhibitor Diprotin A (IC50 of 2.69 ± 1.09 µM, n = 6), they all showed high abundance of at least 105. Additionally, most peptides represented novel sequences that were not previously reported in the literature as DPP4-inhibiting peptides. Pooled peptide fractions from each sample did not show inhibition at the tested concentration, although permeate from a dairy plant showed 34.41% ± 8.27 (n = 3) DPP4 inhibition at only 1.5% w/w of the permeate concentration. AlphaFold 3 predictions revealed that these peptides and Diprotin A docked at similar positions within the DPP4 active site. These findings provide the basis for future studies on interspecies differences, application of novel binding assays to find DPP4 inhibitors, and further exploration of dairy peptides as potential DPP4 inhibitors.

year: 2025

title: Governing globalization in South Asia through a legal praxis of human rights, development and democracy

authors: Tittawella, Suranjika Erangani

subjects: Globalization

abstract: ABSTRACT

This doctoral thesis in law seeks to understand, and begin to remedy, the immense and avoidable poverty that disenfranchises at least 30 percent of the world's most populous region. Defining South Asia as Bangladesh, Bhutan, India, the Maldives, Nepal, Pakistan and Sri Lanka, the study analyses the multidimensional nature, historical origins and modern dynamics of both this material poverty and poverties of human rights, democracy and development. Both critical analysis and creative response are framed within legal history, human rights jurisprudence, constitutional and administrative law, comparative law and public international law, but the author draws extensively on political economy and history, and partially on philosophy, and cultural studies.

Chapter 1 traces the Western evolution of the universal human rights regime, first  globalized  in 1948 by the Universal Declaration of Human Rights. It also traces South Asian sociopolitical and religious articulations of human dignity and limitations on legitimate power through the ages. Mostly contrary to culturally relativist claims, South Asia's human rights needs are found to be well served by a genuinely universalist regime including justiciable economic, social and cultural rights as inseparable from civil and political.

Chapters 2 and 3 survey the historical  globalizations  that have impacted on South Asia. Although globalization is shown to be a neutral phenomenon, the author identifies the insidious contemporary propagation of a particular neo-liberal ideology as being globalization's inevitable and optimal form. The study analyses this propagation by the International Financial Institutions the World Bank and International Monetary Fund, acting through Structural Adjustment Policies and only partially corrective Poverty Reduction Strategy Papers. Neo-liberalism supposedly unshackles benign market forces from distorting governmental rules to create spontaneous growth that trickles down to the poor; in fact it employs its own rules to privilege the already wealthy, especially Western capital and transnational corporations (TNCs).

The thesis urges South Asia to  govern globalization  pro-actively, seeking the virtuous circle of human rights, plural democracy and equitable development. Positive signs have already included national membership in, and constitutional enshrinement of, universal human rights norms, and certain efforts of civil society and non-governmental organizations, fostered at times by activist judiciaries. 

Chapter 4 nevertheless catalogues overriding failures to internalize plural democracy and the rule of law, leaving rights nominal and democratic structures hollow. Governments have been obsequious to neo-liberal hegemony, insouciant to their underclasses and exploitative of religious schisms in appeal to tyrannous majoritarianism. The South Asian Association for Regional Co-operation is shown as an inadequate response to the region's multidimensional poverties.

Adapting instead the best practices of the Council of Europe, the Organization of American States, the African Union, and the British Commonwealth from Chapter 5, Chapter 6 details a  South Asian Union for Human Rights Development and Democracy  to replace SAARC. This new regional response complements global human rights norms and offers South Asia solidarity in confronting neo-liberalism, and holding TNCs, IFIs and especially their own governments accountable to the rule of law, equitable development, deep democracy, wide human rights, and  larger freedom  in peace and security.

text: Governing globalization in South Asia through a legal praxis of human rights, development and democracy ABSTRACT

This doctoral thesis in law seeks to understand, and begin to remedy, the immense and avoidable poverty that disenfranchises at least 30 percent of the world's most populous region. Defining South Asia as Bangladesh, Bhutan, India, the Maldives, Nepal, Pakistan and Sri Lanka, the study analyses the multidimensional nature, historical origins and modern dynamics of both this material poverty and poverties of human rights, democracy and development. Both critical analysis and creative response are framed within legal history, human rights jurisprudence, constitutional and administrative law, comparative law and public international law, but the author draws extensively on political economy and history, and partially on philosophy, and cultural studies.

Chapter 1 traces the Western evolution of the universal human rights regime, first  globalized  in 1948 by the Universal Declaration of Human Rights. It also traces South Asian sociopolitical and religious articulations of human dignity and limitations on legitimate power through the ages. Mostly contrary to culturally relativist claims, South Asia's human rights needs are found to be well served by a genuinely universalist regime including justiciable economic, social and cultural rights as inseparable from civil and political.

Chapters 2 and 3 survey the historical  globalizations  that have impacted on South Asia. Although globalization is shown to be a neutral phenomenon, the author identifies the insidious contemporary propagation of a particular neo-liberal ideology as being globalization's inevitable and optimal form. The study analyses this propagation by the International Financial Institutions the World Bank and International Monetary Fund, acting through Structural Adjustment Policies and only partially corrective Poverty Reduction Strategy Papers. Neo-liberalism supposedly unshackles benign market forces from distorting governmental rules to create spontaneous growth that trickles down to the poor; in fact it employs its own rules to privilege the already wealthy, especially Western capital and transnational corporations (TNCs).

The thesis urges South Asia to  govern globalization  pro-actively, seeking the virtuous circle of human rights, plural democracy and equitable development. Positive signs have already included national membership in, and constitutional enshrinement of, universal human rights norms, and certain efforts of civil society and non-governmental organizations, fostered at times by activist judiciaries. 

Chapter 4 nevertheless catalogues overriding failures to internalize plural democracy and the rule of law, leaving rights nominal and democratic structures hollow. Governments have been obsequious to neo-liberal hegemony, insouciant to their underclasses and exploitative of religious schisms in appeal to tyrannous majoritarianism. The South Asian Association for Regional Co-operation is shown as an inadequate response to the region's multidimensional poverties.

Adapting instead the best practices of the Council of Europe, the Organization of American States, the African Union, and the British Commonwealth from Chapter 5, Chapter 6 details a  South Asian Union for Human Rights Development and Democracy  to replace SAARC. This new regional response complements global human rights norms and offers South Asia solidarity in confronting neo-liberalism, and holding TNCs, IFIs and especially their own governments accountable to the rule of law, equitable development, deep democracy, wide human rights, and  larger freedom  in peace and security.

year: 2008

title: Early childhood teachers partnering with teacher educators to connect children to taiao (the natural world) through place-based learning

authors: Postlewaight, Gillian

abstract: Initial cycles of an action research project brought together local early childhood (ECE) teachers, and tertiary ECE teacher educators, to explore possible uses of the Ōtātara Outdoor Learning Centre (ŌOLC), adjoining the campus at Hawke’s Bay’s Te Aho a Maui Eastern Institute of Technology (EIT), Napier, New Zealand. EIT is situated below Ōtātara Pa, a historic site that holds cultural and historical significance for local Māori, specifically Ngati Pārau Hapū and Ngati Kahungunu Iwi. Education in New Zealand is underpinned by commitment to Te Tiriti o Waitangi (Treaty of Waitangi), ensuring that the principles; partnership, participation and protection of kaupapa Māori are supported through bicultural curricula. Māori holistic perspectives strengthen this focus and shifting understanding that place-based learning authenticates environmental approaches to education and cultural knowledge. During the first meeting, participants walked the hillside site and shared group discussions. From these conversations, the teachers identified three main themes: establishing connections between children and the physical place, new opportunities for teacher learning and challenges to implementing spontaneous teaching and learning in this unique environment. Future cycles of the research will focus on workshops for teachers to address these themes for teachers’ working with children in the space.

text: Early childhood teachers partnering with teacher educators to connect children to taiao (the natural world) through place-based learning Initial cycles of an action research project brought together local early childhood (ECE) teachers, and tertiary ECE teacher educators, to explore possible uses of the Ōtātara Outdoor Learning Centre (ŌOLC), adjoining the campus at Hawke’s Bay’s Te Aho a Maui Eastern Institute of Technology (EIT), Napier, New Zealand. EIT is situated below Ōtātara Pa, a historic site that holds cultural and historical significance for local Māori, specifically Ngati Pārau Hapū and Ngati Kahungunu Iwi. Education in New Zealand is underpinned by commitment to Te Tiriti o Waitangi (Treaty of Waitangi), ensuring that the principles; partnership, participation and protection of kaupapa Māori are supported through bicultural curricula. Māori holistic perspectives strengthen this focus and shifting understanding that place-based learning authenticates environmental approaches to education and cultural knowledge. During the first meeting, participants walked the hillside site and shared group discussions. From these conversations, the teachers identified three main themes: establishing connections between children and the physical place, new opportunities for teacher learning and challenges to implementing spontaneous teaching and learning in this unique environment. Future cycles of the research will focus on workshops for teachers to address these themes for teachers’ working with children in the space.

year: 2023-04-27