Angelo Dal Belin Peruffo

Immunological studies on chlorophyll-a/b proteins and their distribution in thylakoid membrane domains

The immunological relationships between chlorophyll-a/b proteins from higher-plant thylakoid membranes have been studied by assaying purified chlorophyll proteins (CPs) with polyclonal and monoclonal antibodies. Although low levels of cross-reactions were observed between all light-harvesting proteins, the peripheral antennae (LHCII) were largely distinct from the inner antennae (CP 26 and CP 29). Chlorophyll-protein 24 and LHCI-680 have been proposed to have a role in connecting the inner and outer antennae, respectively, in photosystems I and II, and were closely related. The immunological relationships closely corresponded to the spectral properties. Antibodies were also used for locating chlorophyll-a/b proteins in grana, stroma and bundle-sheath membranes showing a strong lateral heterogeneity, which was maintained following State I State II transition. The only exception to this pattern was a specific LHCII population enriched in State-II stroma membranes. Chlorophyll proteins from bundlesheath chloroplasts, that have only cyclic electron flow, had epitopes distinct from those of their mesophyll homologues.

In vitro assessment of acetic-acid-soluble proteins (glutenin) toxicity in celiac disease

Acetic-acid-soluble storage proteins from gluten of the bread wheat cv. Sprint 3 were fractionated by adsorption chromatography on 2000 A controlled-pore glass (CPG) beads, and glutenin polymers with molecular mass higher than 10(7) Da and free from monomeric gliadins were recovered. The glutenin polymers were found to consist of high-molecular-weight (HMW) and low-molecular-weight (LMW) glutenin subunits. Peptic-tryptic (PT) digests of glutenins were examined for their agglutination activity on human myelogenous leukemia K 562(S) cells, agglutination being strongly correlated with toxicity for the celiac intestine. The peptide fraction at a concentration of 1 g/L of culture medium was able to agglutinate 30% of K 562(S) cells, suggesting a moderate toxic effect. This toxicity may be accounted for by homologies in amino acid sequences between glutenin subunits and alpha/beta- and gamma-gliadins.

Immobilization of rice limit dextrinase on γ-alumina beads and its possible use in starch processing

Limit dextrinase (EC 3·2·1·41) partially purified from rice seeds was immobilized by adsorption on γ-alumina beads. Binding and activity yields were 88 and 52%, respectively. The adsorbed enzyme showed a broader pH optimum and an increased thermal stability compared to the free one. Optimum temperature was between 50 and 60°C and the enzyme retained about 70% of the initial activity after 7 days of incubation at 40°C in the presence of Ca2+. The immobilized biocatalyst degraded pullulan completely to maltotriose and effectively converted both acid hydrolysed amylodextrins and β-limit dextrins into maltose and maltotriose. The possibility of using a debranching enzyme of plant origin in starch processing can be considered to be a new approach for the improvement of the quality of sugar syrups used in the food industry.