Protein assembly and heat stability in developing thylakoid membranes during greening.

The development of the thylakoid membrane was studied during illumination of dark-grown barley seedlings by using biochemical methods, and Fourier transform infrared and spin label electron paramagnetic resonance spectroscopic techniques. Correlated, gross changes in the secondary structure of membrane proteins, conformation, composition, and dynamics of lipid acyl chains, SDS/PAGE pattern, and thermally induced structural alterations show that greening is accompanied with the reorganization of membrane protein assemblies and the protein-lipid interface. Changes in overall membrane fluidity and noncovalent protein-lipid interactions are not monotonic, despite the monotonic accumulation of chlorophyll, LHCII [light-harvesting chlorophyll a/b-binding (polypeptides) associated with photosystem II] apoproteins, and 18:3 fatty acids that follow a similar time course with highest rates between 12-24 h of greening.

Transitional steps in the solubilization of protein-containing membranes and liposomes by nonionic detergent.

Membrane solubilization by dodecyl maltoside was studied, using Ca(2+)-ATPase membranes and liposome preparations as prototypes of biological membranes. In equilibrium dialysis experiments, transition from saturable incorporation of monomeric detergent into the membrane to cooperative binding already occurred at a free detergent concentration about 50% of the cmc. This transition was discontinuous for unilamellar liposomes of dioleoylphosphatidylcholine, but gradual for Ca(2+)-ATPase membranes and multilayered liposomes of sarcoplasmic reticulum lipid.

Long-term hypotensive effects of an angiotensin converting enzyme inhibitor in spontaneously hypertensive rats: is there a role for vascular structure?

Male spontaneously hypertensive rats (SHR) were treated from 4 to 24 weeks of age with perindopril, an angiotensin converting enzyme (ACE) inhibitor, in doses of 0.4 and 0.8 mg/kg per day; we investigated the effects of these doses on blood pressure during and after withdrawal of treatment, and on the structural and functional characteristics of the resistance vessels.