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Weizmann Bilim Enstitüsü, İsrail’de Kudüs’ün 40 km batısında Rehovot’ta bulunan, doğa bilimleri ve matematik alanında dünyanın önde gelen multidisipliner araştırma enstitülerinden biridir. Enstitü, merak ve yaratıcılıkla sürdürülen oldukça önemli temel araştırma ve keşiflerin yapıldığı başarılarla dolu tarihsel bir geçmişe sahiptir. Weizmann Enstitüsü, aktif bir araştırma merkezi olmasının yanında, kuruluşundan itibaren İsrail bilimine öncülük eden eğitimin önemli bir parçası olarak rol oynamaktadır.

Examines the azide binding to the trinuclear copper center in laccase and ascorbate oxidase. Use of electron paramagnetic resonance (EPR) and pulsed electron-nuclear double resonance spectroscopies; Measurement of temperature and microwave power for EPR; Interaction of oxygen with trinuclear center of ligand binding.

The membrane potential of rat basophilic leukemia cells (RBL-2H3 cell line) has been determined by monitoring the distribution of the lipophilic [3H] tetraphenylphosphonium cation between the cells and the extracellular medium. By this method, the determined potential of these cells, passively sensitized with IgE, is -93 +/- 5 mV (mean +/- SEM, interior negative). Almost 40% of this membrane potential is rapidly collapsed upon the addition of the proton carrier, carbonyl cyanide p-trifluoromethoxyphenyl hydrazone (FCCP). It is suggested that the FCCP-sensitive fraction of the total membrane potential results from the accumulation of this cation by the mitochondria, which maintains a negative membrane potential. Thus, the resting plasma membrane potential of these cells equals -55 +/- 6 mV. During the process of immunological stimulation by antibodies directed against cell membrane bound IgE, the membrane potential decreases. Moreover, there is a correlation between the extent of degranulation of the cells and the depolarization. It is concluded that in common with other secretory systems, depolarization of the plasma membrane is involved in the stimulus-secretion coupling of the histamine secreting RBL cells. [ABSTRACT FROM AUTHOR]

Molecules encoded by the class 1 major histocompatibility genes bind short (nonameric) peptides produced by intracellular proteolysis of antigens. These complexes formed intracellularly are then expressed on membranes of target cells and recognized by the antigen receptor of cytolytic T cells. No binding of externally added peptides could so far be monitored directly on the antigen presenting cells, although cytotoxicity experiments and indirect binding assays provided evidence for its existence. Here we report experiments where specific binding to class I molecules, of externally added peptides, has been monitored on living cells. N-terminal biotin-labelled Kd- restricted peptides (residues 147-155, residues 147-158, and an analogue lacking the arginine at position 156. derived from the sequence of the influenza A virus nucleoprotein) were incubated with murine H-2Kd mastocytoma cells (line P815) at 4°C. The binding on surface of live, intact cells was then demonstrated fluorometrically via the interaction of a streptavidin-phycoerythrin conjugate with the biotin-labelled peptides. Thus, this binding does not involve processing, and its specificity in terms of peptide structure was established by competition with the respective unmodified peptides. The specificity of binding to class I molecules was demonstrated by blocking experiments using monoclonal antibodies specific for H-2Kd. Finally, a correlation was observed between the results of peptide binding measurements and those of cytotoxicity assays. [ABSTRACT FROM AUTHOR]