This article explores the changing ways ‘environment’ has been represented in the discourses of environmental education and education for sustainable development (ESD) in United Nations (and related) publications since the 1970s. It draws on the writings of Jean-Luc Nancy and discusses the increasingly dominant view of the environment as a ‘natural resource base for economic and social development’ (United Nations, 2002, p. 2) and how this instrumentalisation of nature is produced by discourses and ‘ecotechnologies’ that ‘identify and define the natural realm in our relationship with it’ (Boetzkes, 2010, p. 29). This denaturation of nature is reflected in the priorities for sustainable development discussed at Rio+20 and proposed successor UNESCO projects. The article argues for the need to reassert the intrinsic value of ‘environment’ in education discourses and discusses strategies for so doing. The article is intended as a wake-up call to the changing context of the ‘environment’ in ESD discourses. In particular, we need to respond to the recent UNESCO (2013a, 2013b) direction of global citizenship education as the successor to the UN Decade of Education for Sustainable Development 2005–2014 that continues to reinforce an instrumentalist view of the environment as part of contributing to ‘a more just, peaceful, tolerant, inclusive, secure and sustainable world’ (UNESCO, 2013a, p. 3).

The LEA-like protein previously isolated from a homogenate of pea (Pisum sativum L.) embryonic axes heated at 80°C for 10 min (Russouw et al., 1995) was purified without exposure to heat. Peptides produced by trypsin digestion were separated by HPLC and sequenced. The protein was identified as a member of the LEA group I family. The conformation of the protein was compared before and after heat treatment by antibody affinity, circular dichroism spectroscopy, fluorescence spectroscopy and 8-anilino-1-naphthalenesulfonic acid binding. No differences could be detected, demonstrating that the protein was not irreversibly denatured by exposure to high temperature.

The major whey proteins IgG, serum albumin and α-lactalbumin were purified from camel milk using gel permeation and ion-exchange chromatography. Specific antisera against each of them were raised and used to quantify their heat denaturation in early or mature milk over a range of 60–90 °C for 10–60 min using the single radial immunodiffusion technique. The heat denaturation midpoints for the mature milk heated 30 min were 67·2, 73·0 and 77·5 °C for IgG, albumin and α-lactalbumin respectively. The early milk was more sensitive to heat treatment with coagulation at low temperature and heat denaturation midpoints of 64·8, 71·6 and 72·6 °C respectively. This difference was related to the high IgG content of the early milk (12·6 mg/ml v. 0·5 mg/ml for the mature milk) and stresses the importance of monitoring the IgG level of milk to assess the absence of colostrum.

Heat-induced inactivation of bovine plasmin, denaturation of β-lactoglobulin (β-lg), the interactions between both species and casein micelles and the subsequent net effect on proteolysis of β-casein was studied in a model system consisting of phosphocasein and β-lg in synthetic milk ultrafiltrate. The inactivation of plasmin and denaturation of β-lg were first order reactions, with the rate of inactivation of plasmin being greater than the rate of denaturation of β-lg. The predominant mechanism involved in the denaturation of plasmin in the temperature range 65–80 °C was its interaction with β-lg (kr at 60 °C, 0·0526; Ea, 176 KJ/mol). At the point of complete inactivation of plasmin ~45% of the β-lg remained undenatured. Thermal inactivation of plasmin through other mechanisms was negligible. The association of β-lg with the casein micelles at 60 °C had a rate constant of 3·71×10−5 min−1 and an Ea of 259 KJ/mol; thermal denaturation of β-lg was of much less importance, with a rate constant at 60 °C of the order of 1×10−10 min−1 and an Ea of 250 KJ/mol. On denaturation of all β-lg in the system, a maximum of ~55% was associated with the casein micelles. The effect of heating on the subsequent hydrolysis of β-casein indicated that the level of plasmin activity was the most important factor affecting proteolysis, while the interaction of β-lg with the casein micelles had limited effect. Overall, thermal stability of plasmin in milk is very much dependent upon its interaction with β-lg.

Microfiltration and ultrafiltration were used to manufacture skim milks with an increased or reduced concentration of whey proteins, while keeping the casein and milk salts concentrations constant. The skim milks were heated on a pilot-scale UHT plant at 80, 90 and 120 °C. The heat-induced denaturation and aggregation of β-lactoglobulin (β-lg), α-lactalbumin (α-la) and bovine serum albumin (BSA) were quantified by polyacrylamide gel electrophoresis. Apparent rate constants and reaction orders were calculated for β-lg, α-la and BSA denaturation. Rates of β-lg, α-la and BSA denaturation increased with increasing whey protein concentration. The rate of α-la and BSA denaturation was affected to a greater extent than β-lg by the change in whey protein concentration. After heating at 120 °C for 160 s, the concentration of β-lg and α-la associated with the casein micelles increased as the initial concentration of whey proteins increased.

Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used to monitor changes in the secondary structure and thermal stability of β-lactoglobulin A and B in the presence of sodium dodecyl sulphate (SDS), N-ethylmaleimide (NEM), urea and cysteine. An increase in the thermal stabilities of both proteins was noted in the presence of 10 mM-SDS. In the presence of 50 mM-SDS, there was extensive denaturation of both variants. In general, the β-strand/β-sheet regions in the secondary structure of both variants were very susceptible to denaturation by SDS and cysteine, suggesting that these regions may be held by hydrophobic and disulphide bonds. At ambient temperature and physiological pH, a notable difference was observed in the 1636 and 1627 cm−1 regions of the FTIR spectra of the two β-lg variants. The results suggest possible differences in the nature of the β-sheet/β-strand distribution/content of the two proteins. Urea and NEM at a concentration of 50 mM, had little effect on the secondary structure and denaturation of both variants. New findings are presented which further indicate that although the β-lg B variant showed greater thermal stability than the A variant in all the cases studied, its denaturation temperature and secondary structure were affected to a greater extent by the protein perturbants than β-lg A.

Effects of high pressure (HP) on average casein micelle size and denaturation of α-lactalbumin (α-la) and β-lactoglobulin (β-lg) in raw skim bovine milk were studied over a range of conditions. Micelle size was not influenced by treatment at pressures <200 MPa, but treatment at 250 MPa increased micelle size by ∼25%, while treatment at [ges ]300 MPa irreversibly reduced it to ∼50% of that in untreated milk. The increase in micelle size after treatment at 250 MPa was greater with increasing treatment time and temperature and milk pH. Treatment times [ges ]2 min at 400 MPa resulted in similar levels of micelle disruption, but increasing milk pH to 7·0 partially stabilised micelles against HP-induced disruption. Denaturation of α-la did not occur [les ]400 MPa, whereas β-lg was denatured at pressures >100 MPa. Denaturation of α-la and β-lg increased with increasing pressure, treatment time and temperature and milk pH. The majority of denatured β-lg was apparently associated with casein micelles. These effects of HP on casein micelles and whey proteins in milk may have significant implications for properties of products made from HP-treated milk.

Pure rat brain tubulin is readily palmitoylated in vitro using [3H]palmitoyl CoA but no added enzymes. A maximum of approximately six palmitic acids are added per dimer in 2–3 h at 36–37 °C under native conditions. Both α and β tubulin are labeled, and 63–73% of the label was hydroxylamine-labile, presumed thioesters. Labeling increases with increasing pH and temperature, and with low concentrations of guanidine HCl or KCl (but not with urea) to a maximum of ∼13 palmitates/dimer. High SDS and guanidine HCl concentrations are inhibitory. At no time could all 20 cysteine residues of the dimer be palmitoylated. Polymerization to microtubules, or use of tubulin S, markedly decreases the accessibility of the palmitoylation sites. Palmitoylation increases the electrophoretic mobility of a portion of α tubulin toward the β band. Palmitoylated tubulin binds a colchicine analogue normally, but during three warm/cold polymerization/depolymerization cycles there is a progressive loss of palmitoylated tubulin, indicating decreased polymerization competence. We postulate that local electrostatic factors are major regulators of reactivity of tubulin cysteine residues toward palmitoyl CoA, and that the negative charges surrounding a number of the cysteines are sensitive to negative charges on palmitoyl CoA.

Despite decades of intense study, the complementarity of β-lactams for β-lactamases and penicillin binding proteins is poorly understood. For most of these enzymes, β-lactam binding involves rapid formation of a covalent intermediate. This makes measuring the equilibrium between bound and free β-lactam difficult, effectively precluding measurement of the interaction energy between the ligand and the enzyme. Here, we explore the energetic complementarity of β-lactams for the β-lactamase AmpC through reversible denaturation of adducts of the enzyme with β-lactams. AmpC from Escherichia coli was reversibly denatured by temperature in a two-state manner with a temperature of melting (Tm) of 54.6 °C and a van't Hoff enthalpy of unfolding (ΔHVH) of 182 kcal/mol. Solvent denaturation gave a Gibbs free energy of unfolding in the absence of denaturant (ΔGuH2O) of 14.0 kcal/mol. Ligand binding perturbed the stability of the enzyme. The penicillin cloxacillin stabilized AmpC by 3.2 kcal/mol (ΔTm = +5.8 °C); the monobactam aztreonam stabilized the enzyme by 2.7 kcal/mol (ΔTm = +4.9 °C). Both acylating inhibitors complement the active site. Surprisingly, the oxacephem moxalactam and the carbapenem imipenem both destabilized AmpC, by 1.8 kcal/mol (ΔTm = −3.2 °C) and 0.7 kcal/mol (ΔTm = −1.2 °C), respectively. These β-lactams, which share nonhydrogen substituents in the 6(7)α position of the β-lactam ring, make unfavorable noncovalent interactions with the enzyme. Complexes of AmpC with transition state analog inhibitors were also reversibly denatured; both benzo(b)thiophene-2-boronic acid (BZBTH2B) and p-nitrophenyl phenylphosphonate (PNPP) stabilized AmpC. Finally, a catalytically inactive mutant of AmpC, Y150F, was reversibly denatured. It was 0.7 kcal/mol (ΔTm = −1.3 °C) less stable than wild-type (WT) by thermal denaturation. Both the cloxacillin and the moxalactam adducts with Y150F were significantly destabilized relative to their WT counterparts, suggesting that this residue plays a role in recognizing the acylated intermediate of the β-lactamase reaction. Reversible denaturation allows for energetic analyses of the complementarity of AmpC for β-lactams, through ligand binding, and for itself, through residue substitution. Reversible denaturation may be a useful way to study ligand complementarity to other β-lactam binding proteins as well.

Insulin-like growth factor (IGF-1) contains three disulfide bonds. In the presence of denaturant and thiol catalyst, IGF-1 shuffles its native disulfide bonds and denatures to form a mixture of scrambled isomers. The composition of scrambled IGF varies under different denaturing conditions. Among the 14 possible scrambled IGF isomers, the yield of the beads-form isomer is shown to be directly proportional to the strength of the denaturing condition. This paper demonstrates a new approach to quantify the extent of unfolding of the denatured protein.

The energetics of structural changes in the holo and apo forms of α-lactalbumin and the transition between their native and denatured states induced by binding Ca2+ and Na+ have been studied by differential scanning and isothermal titration microcalorimetry and circular dichroism spectroscopy under various solvent conditions. Removal of Ca2+ from the protein enhances its sensitivity to pH and ionic conditions due to noncompensated negative charge–charge interactions at the cation binding site, which significantly reduces its overall stability. At neutral pH and low ionic strength, the native structure of apo-α-lactalbumin is stable below 14 °C and undergoes a conformational change to a native-like molten globule intermediate at temperatures above 25 °C. The denaturation of either holo- or apo-α-lactalbumin is a highly cooperative process that is characterized by an enthalpy of similar magnitude when calculated at the same temperature. Measured by direct calorimetric titration, the enthalpy of Ca2+-binding to apo-LA at pH 7.5 is −7.1 kJ mol−1 at 5.0 °C, which is essentially invariant to protonation effects. This small enthalpy effect infers that stabilization of α-lactalbumin by Ca2+ is primarily an entropy driven process, presumably arising from electrostatic interactions and the hydration effect. In contrast to the binding of calcium, the interaction of sodium with apo-LA does not produce a noticeable heat effect and is characterized by its ionic nature rather than specific binding to the metal-binding site. Characterization of the conformational stability and ligand binding energetics of α-lactalbumin as a function of solvent conditions furnishes significant insight regarding the molecular flexibility and regulatory mechanism mediated by this protein.