Eco-friendly Synthesis of Gold Nanoparticles Using Camellia sinensis Phytoextracts

Biosynthesis of metal nanoparticles using plant materials involves a fairly rapid reduction of metallic materials. The reduction potential of phytochemicals in a tea extract to reduce gold salt (NaAuCl4) to the highly homogenous gold nanoparticles is presented. Phytoextracts were derived from the mixture of Camellia sinensis var. sinensis and Camellia sinensis var. assamica (green tea) leaves. The appearance of the phytoextract's sloping absorption peak with Au salt at the wavelength range 530-550 nm corresponded to the absorption of gold nanoparticles. Obtained nanoparticles were purified from phytoextract excess by centrifugation. Then they were studied by Raman and FTIR spectroscopy and AFM. It was found that the size of produced gold nanoparticles was in the range from 3 nm to 10 n

The Arabidopsis thaliana ATP-binding cassette proteins: an emerging superfamily

Solute transport systems are one of the major ways in which organisms interact with their environment, Typically, transport is catalysed by integral membrane proteins, of which one of the largest groups is the ATP-binding cassette (ABC) proteins. On the basis of sequence similarities, a large family of ABC proteins has been identified in Arabidopsis, A total of 60 open reading frames (ORFs) encoding ABC proteins were identified by BLAST homology searching of the nuclear genome. These 60 putative proteins include 89 ABC domains. Based on the assignment of transmembrane domains (TMDs), at least 49 of the 60 proteins identified are ABC transporters, Of these 49 proteins, 28 are full-length ABC transporters (eight of which have been described previously), and 21 are uncharacterized half-transporters. Three of the remaining proteins identified appear to be soluble, lacking identifiable TMDs, and most likely have non-transport functions. The eight other ORFs have homology to the nucleotide-binding and transmembrane components of multi-subunit permeases. The majority of ABC proteins found in Arabidopsis can, on the basis of sequence homology, be assigned to subfamilies equivalent to those found in the yeast genome, This assignment of the Arabidopsis ABC proteins into easily recognizable subfamilies (with distinguishable subclusters) is an important first step in the elucidation of their functional role in higher plants