Dehydrins are a family of proteins associated with cell dehydration. Drought, salinity, and high and low temperature may cause water loss from cells. Cold‐induced dehydrins have been reported in several species. P‐80 is a cold‐induced 80 kDa dehydrin in barley. This protein has the same apparent molecular mass as Dhn5, previously described for barley cv Himalaya. P‐80 was localized in the vicinity of vascular cylinders and in the epidermis of leaves and stems. Both tissues have been reported to be sites of early ice nucleation during controlled freezing. The present authors have proposed that this protein cryoprotects macromolecules and frost‐sensitive structures. In the present study, P‐80 and Dhn5 were purified with the purposes of demonstrating their cryoprotective activity in vitro, and comparing both proteins. More than 95% purity was obtained combining heat treatment, cationic exchange chromatography, preparative denaturant electrophoresis and band electroelution. Western blots showed that P‐80 was the major cold‐induced dehydrin in the cultivars examined in the present study. There was a major band of mRNA that showed expression kinetics consistent with P‐80 accumulation. The RT‐PCR picked one major band when using Dhn5‐specific primers in four cold‐acclimated barley cultivars. Both proteins have a similar amino acid composition, with differences in Arg, Asn + Asp, Glu + Gln, His, and Lys. The analysis of proteolytic fragments of Dhn5 and P‐80 by reverse phase chromatography showed a similar pattern. Furthermore, both proteins were able to cryoprotect lactate dehydrogenase (LDH, EC 1.1.1.27) against freeze/thaw inactivation, showing a similar shape dependence on concentration and almost the same protein dosage that renders 50% of cryoprotection (PD50). Thus, P‐80 and Dhn‐5 share more similarities than expected for two different proteins. Their identities, though, remain to be firmly established. Further research is necessary to establish if the observed in vitro cryoprotective activity of these dehydrins is important for cryoprotection in vivo. The association of cryoprotective activity with K repeats of dehydrins is discussed.

A single dose of SnMP proved effective in controlling severe hyperbilirubinemia in full-term breastfed newborns with high bilirubin levels between 48 and 96 hours. In addition, SnMP eliminated the need for PT and reduced the use of medical resources in the clinical treatment of this problem as well as the related, important and painful, emotional costs for both mothers and infants.

To examine the interaction of human arginase II (EC 3.5.3.1) with substrate and manganese ions, the His120Asn, His145Asn and Asn149Asp mutations were introduced separately. About 53% and 95% of wild‐type arginase activity were expressed by fully manganese activated species of the His120Asn and His145Asn variants, respectively. The Km for arginine (1.4–1.6 mm) was not altered and the wild‐type and mutant enzymes were essentially inactive on agmatine. In contrast, the Asn149Asp mutant expressed almost undetectable activity on arginine, but significant activity on agmatine. The agmatinase activity of Asn149Asp (Km = 2.5 ± 0.2 mm) was markedly resistant to inhibition by arginine. After dialysis against EDTA, the His120Asn variant was totally inactive in the absence of added Mn2+ and contained < 0.1 Mn2+·subunit−1, whereas wild‐type and His145Asn enzymes were half active and contained 1.1 ± 0.1 Mn2+·subunit−1 and 1.3 ± 0.1 Mn2+·subunit−1, respectively. Manganese reactivation of metal‐free to half active species followed hyperbolic kinetics with Kd of 1.8 ± 0.2 × 10−8 m for the wild‐type and His145Asn enzymes and 16.2 ± 0.5 × 10−8 m for the His120Asn variant. Upon mutation, the chromatographic behavior, tryptophan fluorescence properties (λmax = 338–339 nm) and sensitivity to thermal inactivation were not altered. The Asn149→Asp mutation is proposed to generate a conformational change responsible for the altered substrate specificity of arginase II. We also conclude that, in contrast with arginase I, Mn2+A is the more tightly bound metal ion in arginase II.

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Protein denaturation in white wines results into a hazy suspension with precipitate formation, affecting negatively their commercialization. The aim of this study was to identify a number of non-protein factors of wines, which exhibit a modulating effect upon haze formation and interfere with protein precipitation in white wines, applying stepwise multiple regression analysis. The influence of intrinsic non-protein factors, including surface and groundwater quality, on protein haze formation assessed by the heat test was studied. Experiments were performed on 18 Sauvignon Blanc wines from six Chilean valleys. The influence of non-protein factors (pH, electrical conductivity [EC], total and volatile acidity, alcohol, free and total sulfur dioxide, total polyphenols, and chloride, sulfate, K, Na, Ca, Mg, and Fe concentrations) on haze response was evaluated by means of multiple regression analysis. Significant contribution (p < 0.05) of EC, sulfate and Fe concentrations to protein haze was found. Due to multi-collinearity between sulfate and Fe concentrations, the multi-linear model of haze response was reduced to: Haze = -184 + 2.95 × [Protein] -62.3 × [Fe] + 0.17 × EC (ra = 0.901). Electric conductivities of wine and surface water were correlated (p = 0.037); good correlations were also found between sulfate concentrations in wine and surface water (p = 0.003), and groundwater (p = 0.022). No correlation was detected for Fe. This study elucidates that protein haze formation in white wine is a multi-factorial process. Iron, EC, and sulfate, in addition to protein itself, have to be considered as factors that modulate wine protein hazing.