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Biomedical subjects

R G Hiller

Publications and source records attributed to R G Hiller.

34 records · Page 2Linked to original sources
PubMed1990

A genomic clone encoding a cryptophyte phycoerythrin alpha-subunit. Evidence for three alpha-subunits and an N-terminal membrane transit sequence.

A genomic library of Chroomonas (Cryptophyceae) DNA has been constructed in lambda EMBL4. Using a synthetic oligomer as a hybridization probe, a clone containing a phycoerythrin alpha-subunit has been obtained and sequenced. The principal alpha 1- and alpha 2-subunits of the holoprotein have been partially sequenced by sequential Edman degradation and differ from the DNA derived sequence, providing evidence for at least 3 alpha-subunit genes. The nucleotide sequence of the alpha-subunit gene is GC rich and encodes an N-terminal extension which is putatively thylakoid-lumen directing.

Amino Acid Sequence↗
PubMed1983

Biological membranes are rich in low-frequency motion.

Using 13C cross-polarization NMR techniques, we have found that the effect of protein on the dynamics of the hydrocarbon interior of a series of biological membranes is to depress the intensity of motion on the nanosecond timescale (i.e., T1 becomes longer) and to enhance the intensity of motion on the timescale of tens of microseconds (i.e., T1p becomes shorter.)

Animals↗
PubMed1980

The fluidity of chloroplast thylakoid membranes and their constituent lipids: a comparative study by ESR.

Comparative measurements were made of the fluidity of chloroplast thylakoids, total membrane lipids and polar lipids utilizing the order parameter and motion of spin labels. No significant differences were found in the fluidity of membranes or total membrane lipids from a wild type and a mutant barley (Hordeum vulgare chlorina f2 mutant) which lacks chlorophyll b and a 25 000 dalton thylakoid polypeptide. Redistribution of intrinsic, exoplasmic face (EF) membrane particles by unstacking thylakoid membranes in low salt medium also had no effect on membrane fluidity. However, heating of isolated thylakoids decreased membrane fluidity. The fluidity of vesicles composed of membrane lipids is much greater than that of the corresponding membranes. Fluidity of the membranes, however, increased during greening indicating that the rigidity of the membranes, compared with that of total membrane lipids, is not caused by chlorophyll or its associated peptides. It is concluded that the restriction of motion in the acyl chains in the thylakoids is not caused by chlorophyll or the major intrinsic polypeptide but by some other protein components.

Chloroplasts↗
PubMed1977

Effect of linocmycin on the chlorophyll protein complex I content and photosystem I activity of greening leaves.

1. Greening barley and pea leaves treated with lincomycin have a reduced chlorophyll content. Lincomycin dose not alter the proportion of chlorophyll in chlorophyll-protein complex II (CPII) but greatly reduces that in chlorophyll-protein complex I (CPI). 2. Difference spectra show that chloroplasts from lincomycin-treated leaves are deficient in at least two long wavelength forms of chlorophyll ratio of chloroplasts is unaffected by lincomycin but the photochemical P-700/chlorophyll ratio is less than half of that of the control. It is less affected than the chlorophyll-protein complex I content. 4. Photosystem I activity expressed on a chlorophyll basis is unaffected by linocomycin but the light intensity for half saturation is increased 8-fold. 5. Chlorophyll-protein complex I apoprotein content is reduced by lincomycin. No evidence was found for an accumulation of its precursor(s). The relative abundance of major peptides of 18 000, 15 000 and 12 000 daltons in lincomycin-treated chloroplasts is attributed to a general inhibition of greening and associated membrane of formation.

Chlorophyll↗
PubMed1968

Respiratory inhibition in Chlorella produced by "purified" polyethylene glycol 1540.

Polyethylene glycol 1540, added to culture solution in amounts sufficient to reduce the water potential to -10 atmospheres, inhibited respiration in Chlorella much more than mannitol solutions at -10 atmospheres. This occurred despite the purification of the polyethylene glycol by passage through exchange columns. The toxic properties, which developed some time after purification, increased with time of storage of solutions of polyethylene glycol 1540 at room temperature.

Depression, Chemical↗