Deviation from homeoviscous adaptation in Escherichia coli membranes.

The process by which an organism changes the composition of its membranal fatty acids in response to growth temperature, so as to maintain optimal membrane functioning, is known as homeoviscous adaptation (HA). One expression of HA is the constancy of the fluorescence polarization (P) of the lipophilic probe 1,6-diphenyl-1,3,5-hexatriene (DPH) in membranes of cells grown at various temperatures. The P of DPH in the membranes of Escherichia coli was shown by us to be inversely proportional to bacterial growth rate on different carbon sources.

The protonated form of 1-N6-etheno-[erythro-9-(2-hydroxy-3-nonyl)] adenine is identified at the active site of adenosine deaminase.

A novel fluorescent competitive inhibitor of adenosine deaminase (EC 3.5.4.

Laser photobleaching leads to a fluorescence grade adenosine deaminase.

The enzyme adenosine deaminase (adenosine aminohydrolase EC 3.5.4.

Solubilization and characterization of the liver peripheral-type benzodiazepine receptor.

The rat liver membrane-bound and digitonin-solubilized peripheral-type benzodiazepine receptors (mPBZR and dsPBZR, respectively) were characterized. Forty percent of the receptors were solubilized from a liver homogenate with 0.25% digitonin.

Adenosine deaminase in cell transformation. Biophysical manifestation of membrane dynamics.

Cell transformation is associated with a dramatic collapse of a graphic fingerprint characteristic of normal cells, as measured by phase fluorimetry. This is demonstrated on adenosine deaminase (ADA, EC 3.5.

Adenosine deaminase-complexing protein from bovine kidney. Isolation of two distinct subunits.

We have isolated a complex of two proteins from bovine kidney that bind to adenosine deaminase immobilized on Sepharose 4B. One protein, with Mr = 110,000, comigrates on both PAGE and SDS-PAGE gels with complexing protein isolated from rabbit kidney by the method of Schrader et al. (Schrader, W.

Homeoviscous adaptation, growth rate, and morphogenesis in bacteria.

Fluorescence polarization, P, of 1,6-diphenyl-1,3,5-hexatriene was studied in Escherichia coli B/r. Modification of nutritional conditions was not compensated by homeoviscous adaptation, demonstrated to exist for temperature variations. Cell diameter, which is known also to vary with nutrition but not with temperature, was found to be positively correlated with 1/P, and may therefore be regulated by membrane lipid order and fluidity.

Laser photobleaching of human serum: application to fluorescence immunoassays.

Background fluorescence from serum chromophores is substantially reduced by a laser photobleaching method. Human and bovine serum samples were illuminated with 337-nm light from a pulsed N2 laser for a short period of time. The serum emission in the region of 440 to 550 nm was reduced by an order of magnitude with no evident damage to serum proteins as judged by the unchanged activity of alkaline phosphatase and aspartate aminotransferase.

Activation of human lymphocytes by concanavalin A or purified protein derivative results in no alteration of fluorescence polarization of lipid probes although the electrophoretic mobility of the cells is changed.

Upon stimulation with either concanavalin A or the tuberculin antigen, purified protein derivative, human peripheral blood lymphocytes, purified on Ficoll-Hypaque, did not exhibit a concomitant lipid fluidity alteration as measured by fluorescence polarization (P) of the lipid probe, 1,6-diphenyl-1,3-5-hexatriene (DPH). This result was independent of the incubation period, ranging from 10 min to 72 h. However, a general reduction in polarization value, from P = 0.

Fluorescent substrate analogue for adenosine deaminase: 3'-O-[5-(dimethylamino)naphthalene-1-sulfonyl]adenosine.

The synthesis of the fluorescent derivative of adenosine, by reaction with 5-(dimethylamino)naphthalene-1-sulfonyl chloride in dry pyridine at low temperature, yielding 3'-O-[5-(dimethylamino)naphthalene-1-sulfonyl]adenosine (3'-O-dansyladenosine), is here described. 3'-O-Dansyladenosine is partially soluble in water (approximately 10(-4) M) and upon excitation at 325 nm exhibits maximum fluorescence emission at 516 +/- 22 nm (corrected) in buffered aqueous solution at pH 7.6 with a quantum yield of 0.

Membrane dynamic alterations associated with activation of human platelets by thrombin.

Two fluorescent probes, N-carboxymethylisatoic anhydride, which binds to membrane proteins, and 1,6-diphenyl-1,3,5-hexatriene, a lipophilic label, have been used to follow membrane microenvironmental changes. Activation of human platelets by thrombin resulted in a simultaneous increase in values of fluorescence polarization (P) of both probes during the stages of shape change and secretion, which further increased during platelet aggregation. The similar pattern of changes in P for both probes indicates the interdependence of lipids and proteins in the activated platelet membrane.

Membrane dynamic alteration associated with the tumorigenicity of polyoma-transformed and revertant hamster cells.

Steady state fluorescence polarization studies were carried out on membranes of polyoma-virus-transformed, revertants, re-revertants, and normal golden hamster cells. Four clones of revertant cells which exhibit different levels of reversion were isolated. The degree of reversion in these revertant clones was characterized in vitro by their contact inhibition behavior and in vivo by their tumorigenicity to hamsters.

Membrane microenvironmental changes during activation of human blood platelets by thrombin. A study with a fluorescent probe.

Membrane microenvironmental changes associated with thrombin-induced platelet activation were followed by fluorescence intensity and polarization studies of 1,6-diphenyl-1,3,5-hexatriene (DPH)-labeled human platelets. The labeling of washed platelets with DPH did not alter platelet intactness and morphology. In response to thrombin, DPH-labeled platelets exhibited reduced serotonin release, yet aggregation was barely inhibited.

[Changes in paO2 and of acid-base equilibrium of the arterial blood of hypoxemic polyglobulic patients subjected to acute blood depletion].

Partial respiratory gas tension and acid-base equilibrium patterns were examined in polyglobulic patients subjected to acute blood depletion. The increase in oxyhaemoglobin concentration and fall in haematocrit value already described were confirmed. It was also noted that: 1) pH increased significantly in all subjects; 2) urinary osmolarity increased in all subjects; 3) blood sodium and potassium concentration increased significantly in 14 patients (1st group), but fell in the 2nd group (8 subjects).

Fluorescence polarization and viscosities of membrane lipids of 3T3 cells.

Studies of the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene in membranes of normal, transformed, and revertant 3T3 cells allowed estimation of microviscosities (eta) of the lipid bilayers of these cells. Fluorescence polarization values observed with normal cells were significantly lower than those observed with cells transformed either by polyoma virus or by simian virus 40. The values of fluorescence polarization obtained with revertant Py6R1 cells were lower than those obtained with the normal cells.