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Arctic tundra vegetation composition is expected to undergo rapid changes during the coming decades because of changes in climate. Higher air temperatures generally favor growth of deciduous shrubs, often at the cost of moss growth. Mosses are considered to be very important to critical tundra ecosystem processes involved in water and energy exchange, but very little empirical data are available.

Effects of hydrogen bonding and the axial ligand interaction on the B800 band in two LH2 complexes Rhodopseudomonas (Rps.) acidophila and Rhodospirillum (Rs.) molischianum have been theo retically investigated by using density functional theory. The local electrostatic environment of the B800 bacteriochlorophyll is simulated as an atomic charge field consisting of the pigments in the protomer unit

Ribonucleotide reductases (RNRs) catalyze the reduction of ribonucleotides to deoxyribonucleotides, the building blocks for DNA synthesis, and are found in all but a few organisms. RNRs use radical chemistry to catalyze the reduction reaction. Despite RNR having evolved several mechanisms for generation of different kinds of essential radicals across a large evolutionary time frame, this initial r

Protein C (PC) is activated to an essential anticoagulant enzyme (activated PC or APC) by thrombin (T) bound to thrombomodulin (TM), a membrane receptor present on the surface of endothelial cells. The understanding of this complex biological system is in part limited due to the lack of integration of experimental and structural data. In the work presented here, we analyze the PC-T-TM pathway in t

The p53 tumor suppressor gene regulates growth arrest and apoptosis after DNA damage. Recent studies suggest that p53 is inactive in vascular smooth muscle cells (VSMCs) in human angioplasty restenosis, promoting VSMC accumulation and vessel stenosis. In contrast, the success of irradiation (brachytherapy) for in-stent restenosis argues that DNA-damage p53 responses are intact. We examined p53 exp

The generation of thrombin by the prothrombinase complex is a key event in coagulation. In this complex, the activated form of coagulation factor V (FVa) serves as an essential cofactor to factor Xa (FXa) in the activation of prothrombin to thrombin. The enzyme FXa is virtually ineffective in the absence of its cofactor. The assembly of FXa with its cofactor FVa on negatively charged phospholipid

Apolipoprotein RI (apoM) is a novel apolipoprotein that is predominantly present in high-density lipoprotein, Sensitive sequence starches, threading and comparative model building experiments revealed apoM to be structurally related to the lipocalin protein family. In a 3D model, characterized by an eight-stranded anti-parallel beta -barrel, a segment including Asn135 could adopt a closed or open

An emerging number of diseases and therapeutic approaches with defined involvement of the complement system justify a need for specific markers reflecting activation of particular effector arms of the complement cascade. Measurement of such soluble markers in circulation is a challenge since the specificity of antibodies must be limited to activated complement fragments but not predominant and ubi