Purification of a 6.5 kDa protease inhibitor from Amazon Inga umbratica seeds effective against serine proteases of the boll weevil Anthonomus grandis

A 6.5 kDa serine protease inhibitor was purified by anion-exchange chromatography from the crude extract of the Inga umbratica seeds, containing inhibitor isoforms ranging from 6.3 to 6.7 kDa and protease inhibitors of approximately 19 kDa. The purified protein was characterized as a potent inhibitor against trypsin and chymotrypsin and it was named I. umbratica trypsin and chymotrypsin inhibitor (IUTCI). MALDI-TOF spectra of the IUTCI, in the presence of DTT, showed six disulfide bonds content, suggesting that this inhibitor belongs to Bowman-Birk family. The circular dichroism spectroscopy indicates that IUTCI is predominantly formed by unordered and beta-sheet secondary structure. It was also characterized, by fluorescence spectroscopy, as a stable protein at range of pH from 5.0 to 7.0. Moreover, this inhibitor at concentration of 75 microM presented a remarkable inhibitory activity (60%) against digestive serine proteases from boll weevil Anthonomus grandis, an important economical cotton pest.     

Relaxometric evaluation of novel manganese(II) complexes for application as contrast agents in magnetic resonance imaging

Three novel Mn(II) complexes bearing benzyloxymethyl functionalities are reported and their ability to enhance water (1H and 17O) relaxation times is investigated in detail. Two of them contain one coordinated water molecule and display relaxivity values only slightly smaller than those shown by the most clinically used contrast agents (e.g. [Gd(DTPA)(H2O)]2-). Moreover, in these Mn(II) chelates the exchange rate of the coordinated water is ca. one order of magnitude higher if compared to the exchange rates previously reported for Gd(III) complexes with octadentate ligands. The occurrence of such fast exchange rates of the coordinated water is exploited in the formation of macromolecular adducts with human serum albumin to attain systems displaying relaxivity values in the upper range of those so far reported for analogous Gd(III) systems. These results strongly support the view that Mn(II) complexes, in spite of the lower effective magnetic moment, can be considered as viable alternatives to the currently used Gd(III) complexes as contrast agents for MRI applications.     

Tetrastylis ovalis: A second case of bat-pollinated passionflower (Passifloraceae)

The floral biology ofTetrastylis ovalis and its pollination by bats was studied in southeastern Brazil. The flowers ofT. ovalis seem more fitted to bat-pollination than those ofPassiflora mucronata, the other known chiropterophilous passionflower. Two species of bats were observed visiting flowers ofT. ovalis: the phyllostomidsGlossophaga soricina andRhinophylla pumilio. Due to the attributes ofTetrastylis, its presumed primitiveness and a better defined bat-pollination syndrome we suggest that chiropterophily evolved independently in the former genus and inPassiflora.