Short communication: investigating the effect of saffron (Crocus sativus L.) nano-sizing on its colour extraction efficiency: a preliminary study.

This study investigated the effect of saffron nano-sizing on its the colour extraction yield. The whole stigma was ball-milled at three different times (10, 20 and 100 h), immediately or with a 24 h delay was submitted to absorption test, and then the colour extraction efficiency was determined. When stigma was milled for 100 h, its particle size was reduced to less than 20 nm, as shown by SEM and TEM images, and its extraction efficiency was considerably increased by 19.8% as compared with the stigma blended for 10 min. However with a 24 h delay between the end of milling and absorption test, the yield of colour extraction significantly decreased. The recommended milling conditions resulting in extraction efficiency of 16.2% (in comparison with stigma blended for 10 min) were determined to be the milling for 10 h with initial tendering prior to milling operation.

Crystal structure and statistical coupling analysis of highly glycosylated peroxidase from royal palm tree (Roystonea regia).

Royal palm tree peroxidase (RPTP) is a very stable enzyme in regards to acidity, temperature, H(2)O(2), and organic solvents. Thus, RPTP is a promising candidate for developing H(2)O(2)-sensitive biosensors for diverse applications in industry and analytical chemistry. RPTP belongs to the family of class III secretory plant peroxidases, which include horseradish peroxidase isozyme C, soybean and peanut peroxidases. Here we report the X-ray structure of native RPTP isolated from royal palm tree (Roystonea regia) refined to a resolution of 1.85A. RPTP has the same overall folding pattern of the plant peroxidase superfamily, and it contains one heme group and two calcium-binding sites in similar locations. The three-dimensional structure of RPTP was solved for a hydroperoxide complex state, and it revealed a bound 2-(N-morpholino) ethanesulfonic acid molecule (MES) positioned at a putative substrate-binding secondary site. Nine N-glycosylation sites are clearly defined in the RPTP electron-density maps, revealing for the first time conformations of the glycan chains of this highly glycosylated enzyme. Furthermore, statistical coupling analysis (SCA) of the plant peroxidase superfamily was performed. This sequence-based method identified a set of evolutionarily conserved sites that mapped to regions surrounding the heme prosthetic group. The SCA matrix also predicted a set of energetically coupled residues that are involved in the maintenance of the structural folding of plant peroxidases. The combination of crystallographic data and SCA analysis provides information about the key structural elements that could contribute to explaining the unique stability of RPTP.