Trials with Sangiovese grafted on several grapevine rootstocks in two different areas of Tuscany

Researches were conducted in the ‘Morellino di Scansano’ D.O.C. area, province of Grosseto and in the area of D.O.C.G. ‘Chianti Classico’, province of Florence. The experimental vineyards were set up in 1993 and 1994 in Chianti Classico and in the Morellino di Scansano’ area respectively with ‘Sangiovese’ grapevines grafted onto twelve rootstocks (‘101-14Mgt’, ‘1103P’, ‘110R’, ‘140Ru’, ‘161-49’, ‘3309C’ ‘41B’, ‘420A’, ‘775P’, ‘779P’, ‘K5BB’, ‘SO4’)., In addition Gravesac was planted in the first zone and eight more rootstocks ('Rupestris Du Lot', '157-11', '34 EM', 'K125AA', ‘225Ru’, '17-37', 'Fercal', '1045P)' in Chianti Classico. Both soils were non calcareous. In Chianti Classico the soil was a sandyclay (pH 8.0) while in the 'Morellino di Scansano' area the soil was a clay loam sandy (pH 6.9). This latter area was characterised by warmer and dry conditions during summer. In the 'Morellino di Scansano' area a less vine vigour was induced by 41B’, 'Gravesac’ and ‘SO4’ while ‘779P’, ‘161-49’ and ‘140Ru’ showed to increase plant vigour. The yield was not strictly correlated to vigour. The more productive vines were grafted onto ‘775P’, followed by ‘779P’, ‘101-14’, 110R’, 140Ru’ and ‘K5BB’', while '41B' induced lower berry size and productivity and elevated sugar levels also maintaining good acidity, low pH, medium anthocyanin content of the berry. Berry sugar accumulation was the highest with ‘101-14’, 420A’ and ‘110R’, and lower with ’K5BB’. The berry anthocyanin and polyphenol richness were positively influenced by ‘SO4’and ‘779P’ and to a lesser extent by ‘’420A’, ‘’101-14, ‘110R’, ‘161-49’ and 140Ru’, while 775P’ ‘K5BB’, ‘Gravesac’, and ‘1103P’ induced lower levels. In the Chianti Classico area '41B’ and ‘420A’ determined low vine vigour, while ‘Rupestris Du Lot’ significantly decreased yield. These results showed non-negligible differences of performances among the various rootstocks according to soil and climatic conditions. The best performances were given by ‘110R’, which was the most homogeneous in both ambient

Toward the engineering of a super efficient enzyme

The catalytic activity of a mutant of Photobacterium leiognathi Cu,Zn superoxide dismutase in which the Glu59 residue, conserved in most bacterial variants of the enzyme, has been replaced by glutamine was investigated by pulse radiolysis. At neutral pH the enzyme was found to have a k(cat)/K(M) of 1.0 ± 0.1 x 1010 M-1 s-1 the highest value ever found for any superoxide dismutase. Brownian dynamics simulation suggests that such a high value is due to an enhanced substrate attraction by the modified electric field distribution. The mutant is also characterized by an active-site widely accessible for the solvent, since iodide is able to interact with the copper atom with an affinity constant twice as high as that found in the native enzyme. The large solvent accessible surface of the copper site together with a favorable distribution of the protein-generated electric field gives rise to the most efficient enzyme ever found with activity close to the diffusion limit

The mitochondrial oxoglutarate carrier: Structural and dynamic properties of transmembrane segment IV studied by site-directed spin labeling

The structural and dynamic features of the fourth transmembrane segment of the mitochondrial oxoglutarate carrier were investigated using site-directed spin labeling and electron paramagnetic resonance (EPR). Using a functional carrier protein with native cysteines replaced with serines, the 18 consecutive residues from S184 to S201 which are believed to form the transmembrane segment IV were substituted individually with cysteine and labeled with a thiol-selective nitroxide reagent. Most of the labeled mutants exhibited significant oxoglutarate transport in reconstituted liposomes, where they were examined by EPR as a function of the incident microwave power in the presence and absence of two paramagnetic perturbants, i.e., the hydrophobic molecular oxygen or the hydrophilic chromium oxalate complex. The periodicity of the sequence-specific variation in the spin-label mobility and the O2 accessibility parameters unambiguously identifies the fourth transmembrane segment of the mitochondrial oxoglutarate carrier as an α-helix. The accessibility to chromium oxalate is out of phase with oxygen accessibility, indicating that the helix is amphipatic, with the hydrophilic face containing the residues found to be important for transport activity by site-directed mutagenesis and chemical modification. The helix is strongly packed, as indicated by the values of normalized mobility, which also suggest that the conformational changes occurring during transport probably involve the N-terminal region of the helix