Effect of gamma-radiation and microwave heating on endosperm microstructure in relation to some technological properties of wheat grain.

Grains of the Polish winter wheat variety Begra were subject to gamma-radiation (60Co) within the dose range of 0.05-10 kGy and microwave treatment from 15 to 180 s, the latter resulting in a bulk grain temperature ranging from 28 to 98 degrees C. Both processes were responsible for marked structural changes of wheat kernel endosperm and were pronounced with increasing dose of ionizing radiation or with prolonged time of microwave treatment. Endosperm microstructures of wheat kernels treated with gamma-radiation ranging from 0.05 to 0.5 kGy did not differ from that of untreated ones. Only some changes in the structure of starch granules and proteins were observed at doses of 1, 5 and 10 kGy. Simultaneously at the doses of 5 and 10 kGy a statistically significant decrease of falling number, sodium dodecyl sulfate (SDS) sedimentation values, dough stability and energy were observed, while dough weakening progressed. Microwave treatment longer than 90 s caused marked changes in kernel endosperm structure. Some changes of proteins caused by denaturation created visible fibrils as well as high swelling and deformation of starch granules. This was followed by an increase in the falling number value, decrease in the estimated results of SDS sedimentation test, lowering of the percent of gluten washed out and of the dough energy, respectively. Also a significant decrease in bread quality expressed by volume and score was observed with increasing time of exposure to microwave.

Italian buckwheat (Fagopyrum esculentum) starch: physico-chemical and functional characterization and in vitro digestibility.

A study on the physico-chemical properties and structure together with the evaluation of starch digestibility was carried out on starch isolated from buckwheat (Fagopyrum esculentum) cultivated in different Italian areas. Results showed that buckwheat samples analysed were different among them and from wheat starch used as reference. Buckwheat granules were polygonal in shape and had a smaller diameter than the wheat starch granule. The starch obtained from buckwheat had a higher swelling power than the wheat one, probably as a consequence of the wheaker but more extensive bonding forces in the granule. During cooling, buckwheat samples showed a good paste stability.

Proteins of Caulobacter crescentus strongly binding to DNA. Spectroscopic analysis of major histone-like proteins.

The protein composition of deoxyribonucleoprotein (DNP) from Caulobacter crescentus, protected from exogenous nucleases, was analysed. This fraction was obtained by purification of cell lysate on Sephacryl S-400. It contained the following proteins: 13.4 kDa (HCc), 15.2 kDa, 17.5 kDa, 28 kDa and 40 kDa. The strength of protein 15.2 kDa binding to ds-DNA was the same as that of the eukaryotic histones H2A and H2B. Proteins 13.4 kDa (HCc) and 17.5 kDa purified to homogeneity have a UV spectrum identical to protein HU of Escherichia coli which lacks tryptophane and tyrosine. This confirms the classification of protein HCc to the class of HU-like proteins.