Electrophoretic characterisation of fractions collected from gluten protein extracts subjected to size-exclusion high-performance liquid chromatography.

The electrophoretic analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE; reduced and unreduced) of fractions, collected from a size exclusion-high performance liquid chromatography (SE-HPLC) separation of gluten proteins using a column with pore size of around 400A, showed clear resolution for the seven elution ranges studied in two Australian bread wheat lines. Polymeric proteins - high molecular weight (HMW) glutenin subunits, low molecular weight (LMW) glutenin subunits, HMW albumins and some modified omega-gliadins - appeared exclusively in the region within the first peak of the chromatogram (fractions 1 to 5), the limit being a region that resolved as a small peak before the large peak of gliadins and where some omega-gliadins eluted. A larger proportion of HMW glutenin subunits and B subunits contributed to polymer formation of higher molecular weight. The polymer size decreased as the proportion of the other protein components increased.

Rapid and automated characterisation of seed genotype using Micrograd electrophoresis and pattern-matching software.

New precast microgels are described for use in quickly identifying seed of cereal varieties by determining protein composition within an hour. For example, gliadin proteins are extracted from crushed wheat grain, wheatmeal or flour with ethylene glycol (centrifugation not necessary) and 5 microliters extract is applied to a Micrograd gel (3-15% gel gradient) for ten minutes' electrophoresis at 300 volts in sodium lactate buffer (pH 3.1). Alternatively, precast gels are available for SDS gel electrophoresis for examining a different aspect of grain composition as a means of identification. To further expedite identification, software packages have been developed to match the protein pattern for an unknown sample against those of authentic samples, thus to provide quick and definite identity, based on electrophoretic banding, densitometer scan, HPLC profile, multiple antibody reaction or RFLP pattern (PatMatch program). Furthermore, the program WhatWheat offers advice on the best combination of methods to use for a specific task of identification.

The selective iodination of yeast phenylalanine transfer RNA with 125-I.

Yeast tRNA-Phe has been labelled with 125-I under conditions which conserve the tertiary structure. Significant labelling was only found to occur on specific cytidines in single stranded regions, while other cytidines in single stranded regions and all those in the double stranded region underwent iodination to a very small extent. The pattern obtained from iodine labelling satisfies the conformation of a model recently proposed for this tRNA.