There is an increase in the number of people adopting a gluten-free diet, with one-fifth of Australian consumers avoiding certain food or drinks for allergy or intolerance reasons. For most ...consumers, the belief that a gluten-free diet is healthier than a gluten containing diet is unsupported by a formal diagnosis. However, for a small group of subjects who have gluten sensitive disorder, a lifelong, gluten-free diet is required, including avoidance of beer. Prolylendopeptidase enzymes (PEP) cleave gluten proteins after the abundant proline residues and have the potential to destroy gluten proteins and remove or minimize immunoreactive peptides from food. However, PEP treatment may also confound measurement of gluten concentration in food and beverages by destroying epitopes that are used to enumerate gluten peptides - we ask, "does PEP treatment destroy celiac reactive epitopes or merely disguise them from ELISA enumeration?" There is now sufficient data to show that treatment of gluten peptides with bacterial PEP in combination with other proteases, or the fungal Aspergillus niger PEP alone, reduces the immunoreactivity of gluten peptides, with celiac T-cells to near zero. This is also accompanied by destruction of key epitopes that are used by antibodies to enumerate gluten peptides during ELISA reactions. Thus, both immunoreactivity and ELISA measurements are reduced to near zero by PEP treatment. However, definitive evidence of the safety of treated beer for celiacs ideally requires a double-blind crossover, dietary challenge. Consuming sufficient beer to present a suitable load of hordein peptides is not possible, and presenting hordeins in the same form as encountered in treated beer is difficult. The effect of protease treatments on the safety of treated gluten for the remainder the celiac-like diseases, including gluten ataxia and dermatitis herpetiformis, and the larger spectrum of gluten-related disorders, including gluten intolerance and the IgE-mediated allergic responses Bakers asthma, gluten allergy, WDEIA, and urticaria, cannot be definitively assessed until the epitopes involved have been defined. The gluten sensitive disorders and the gluten proteins are reviewed, and the effects of proteolysis on several archetypal gluten peptides are examined.
Summary
Late maturity α‐amylase (
LMA
) and preharvest sprouting (
PHS
) are genetic defects in wheat. They are both characterized by the expression of specific isoforms of α‐amylase in particular ...genotypes in the grain prior to harvest. The enhanced expression of α‐amylase in both
LMA
and
PHS
results in a reduction in Falling Number (FN), a test of gel viscosity, and subsequent downgrading of the grain, along with a reduced price for growers. The FN test is unable to distinguish between
LMA
and
PHS
; thus, both defects are treated similarly when grain is traded. However, in
PHS
‐affected grains, proteases and other degradative process are activated, and this has been shown to have a negative impact on end product quality. No studies have been conducted to determine whether
LMA
is detrimental to end product quality. This work demonstrated that wheat in which an isoform α‐amylase (
TaAmy
3) was overexpressed in the endosperm of developing grain to levels of up to 100‐fold higher than the wild‐type resulted in low FN similar to those seen in
LMA
‐ or
PHS
‐affected grains. This increase had no detrimental effect on starch structure, flour composition and enhanced baking quality, in small‐scale 10‐g baking tests. In these small‐scale tests, overexpression of
TaAmy3
led to increased loaf volume and Maillard‐related browning to levels higher than those in control flours when baking improver was added. These findings raise questions as to the validity of the assumption that (i)
LMA
is detrimental to end product quality and (ii) a low FN is always indicative of a reduction in quality. This work suggests the need for a better understanding of the impact of elevated expression of specific α‐amylase on end product quality.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
The development of a small‐scale spectrophotometric method of determining both onset and peak gelatinisation temperatures of starch is reported. In this assay the changes in absorbance of a dilute ...starch suspension are measured at 380 nm as the suspension is heated to 95°C. The values obtained from this method for both onset and peak gelatinisation temperatures correlate extremely well with those obtained by DSC, but are generally 5°C to 10°C lower. This method works on both pure and crude starch samples and thus has the potential to be used in a high‐throughput format allowing up to 100 samples per day, making it useful for research and breeding programs in which large numbers of impure starch samples need to be assayed. This allows for earlier selection of the lines of interest, which can then be analysed more comprehensively with techniques such as DSC which provide a greater amount of information, thus saving the researchers' time and money.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The nature and subcellular location of cyanide-insensitive respiration and the pyridine nucleotide dehydrogenases were investigated in the cyanobacterium
Anabaena PCC 7120. Oxygen uptake by isolated ...thylakoid membranes in the presence of either NADH, NADPH or duroquinol as substrates, was partially insensitive to KCN at concentrations which completely inhibited plasma membrane-mediated oxygen uptake. The cyanide-insensitive oxidase was not inhibited by salicyl hydroxamic acid (SHAM) or by n-propyl gallate (n-PG), which are inhibitors of the plant mitochondrial alternative oxidase; nor did total membrane proteins cross-react with antibodies raised against the alternative oxidase. We conclude that cyanide-insensitive oxidation is confined to the thylakoid membrane in
Anabaena PCC 7120 and is not catalysed by the alternative oxidase responsible for cyanide-insensitive respiration in plants. Both plasma membranes and thylakoid membranes oxidised NADH and NADPH. Isolated plasma membrane was shown to contain a single type-1 dehydrogenase that is antigenically homologous to complex I of mitochondria and sensitive to the respiratory poison rotenone, but which oxidises both NADH and NADPH. The thylakoid membrane was shown to contain two NAD(P)H dehydrogenases: that responsible for NADH oxidation has inhibition characteristics of a type-2 dehydrogenase while NADPH oxidation may be catalysed by ferredoxin NADP
+-oxidoreductase, the last enzyme in the photosynthetic electron transport chain.
A previously reported Agrobacterium tumefaciens transformation system that transformed wheat cultivar Fielder at high efficiency was shown to also transform eight out of nine Triticum aestivum ...(hexaploid wheat) cultivars tested and two Triticum turgidum (durum wheat) cultivars. Transformation efficiencies of these wheat lines ranged from 1.5 to 51 %. Included amongst this germplasm were elite Australian hexaploid wheat cultivars that are currently in commercial cultivation and two of these cultivars, Gladius and Westonia, were transformed at 32 and 45 % efficiency, respectively. Similar high transformation efficiencies were observed for durum wheat cultivars Kronos (51 %) and Stewart (26 %). This highly efficient transformation system was used to generate transgenic plants in the absence of selection and high heritability of unselected transgenes was observed. Selectable marker free transgenic wheat plants were produced at 3 % efficiency. These data demonstrate highly efficient Agrobacterium transformation of diverse wheat germplasm, including elite cultivars, which enables routine production of selectable marker free transgenics.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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