Copper effect on the protein composition of photosystem II

The definitive version is available at: http://www.blackwell-synergy.com/doi/full/10.1111/j.1399-3054.2000.1100419.xWe provide data from in vitro experiments on the polypeptide composition, photosynthetic electron transport and oxygen evolution activity of intact photosystem II (PSII) preparations under Cu(II) toxicity conditions. Low Cu(II) concentrations (Cu(II) per PSII reaction centre unit≤230) that caused around 50% inhibition of variable chlorophyll a fluorescence and oxygen evolution activity did not affect the polypeptide composition of PSII. However, the extrinsic proteins of 33, 24 and 17 kDa of the oxygen-evolving complex of PSII were removed when samples were treated with 300 μM CuCl2 (Cu(II) per PSII reaction centre unit=1 400). The LHCII antenna complex and D1 protein of the reaction centre of PSII were not affected even at these Cu(II) concentrations. The results indicated that the initial inhibition of the PSII electron transport and oxygen-evolving activity induced by the presence of toxic Cu(II) concentrations occurred before the damage of the oxygen-evolving complex. Indeed, more than 50% inhibition could be achieved in conditions where its protein composition and integrity was apparently preserved.This work was supported by the Dirección General de Investigación Científica y Técnica (Grant PB98-1632).Peer reviewe

Liver transplantation. A summary of our surgical practice.

At the turn of the new century, liver transplant procedures can finally be considered an efficient treatment option. Technology has helped transplant intervention become a preferred treatment for patients with progressive and irreversible liver failure. New immuno-suppressive drugs have been introduced which reduce the patient's immunological reaction to the implanted organ, entail minimal side effects and improve practical applications of liver transplantation. As a result of these technological advanced and proper disease management, liver transplant procedures are no longer thought of as an elite therapy, reserved for selected patients with end stage liver disease. In our opinion, it is now a sound and valid surgical option with strictly defined characteristics, indications and well-understood limits. Throughout the past decade, we have studied and applied this type of intervention and have come to terms with its rapid expansion at both the theoretical and practical levels. The most significant obstacle remaining today is the discrepancy between the ever increasing demand and limited supply of organs. The future of liver transplant lies in overcoming this obstacle. Liver transplant practice began at our Institute on 23 November 1990 with the first surgical intervention to replace an organ. In the past 10 years, we have exceeded 200 liver transplant procedures