Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Algal Proteins”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1987

Non-conventional approaches to food processing in CELSS. I--Algal proteins; characterization and process optimization.

Protein isolate obtained from green algae (Scenedesmus obliquus) cultivated under controlled conditions was characterized. Molecular weight determination of fractionated algal proteins using SDS-polyacrylamide gel electrophoresis revealed a wide spectrum of molecular weights ranging from 15,000 to 220,000. Isoelectric points of dissociated proteins were in the range of 3.95 to 6.20. Amino acid composition of protein isolate compared favorably with FAO standards. High content of essential amino acids leucine, valine, phenylalanine and lysine makes algal protein isolate a high quality component of CELSS diets. To optimize the removal of algal lipids and pigments supercritical carbon dioxide extraction (with and without ethanol as a co-solvent) was used. Addition of ethanol to supercritical CO2 resulted in more efficient removal of algal lipids and produced protein isolate with a good yield and protein recovery. The protein isolate extracted by the above mixture had an improved water solubility.

Amino Acids↗
PubMed1989

Potential utilization of algal protein concentrate as a food ingredient in space habitats.

Green alga Scenedesmus obliquus was studied as one of the potential sources of macronutrients in a space habitat. Algal protein concentrate (70.5% protein) was incorporated into a variety of food products such as bran muffins, fettuccine (spinach noodle imitation) and chocolate chip cookies. Food products containing 20 to 40% of incorporated algal proteins were considered. In the sensory analysis the greenish color of the bran muffins and cookies was not found to be objectional. The mild spinachy flavor (algae flavor) was less detectable in chocolate chip cookies than in bran muffins. The color and taste of the algae noodles were found to be pleasant and compared well with commercially available spinach noodles. Commercially available spray-dried Spirulina algae was also incorporated so the products can be compared with those containing Scenedesmus obliquus concentrate. Food products containing commercial algae had a dark green color and a "burnt after taste" and were less acceptable to the panelists.

Biomass↗
PubMed1991

Uniformly 13C-labeled algal protein used to determine amino acid essentiality in vivo.

The edible alga Spirulina platensis was uniformly labeled with 13C by growth in an atmosphere of pure 13CO2. The labeled biomass was then incorporated into the diet of a laying hen for 27 days. The isotopic enrichment of individual amino acids in egg white and yolk proteins, as well as in various tissues of the hen at the end of the feeding period, was analyzed by negative chemical ionization gas chromatography/mass spectrometry. The amino acids of successive eggs showed one of two exclusive enrichment patterns: complete preservation of the intact carbon skeleton or extensive degradation and resynthesis. The same observation was made in tissue proteins. These patterns were cleanly divided according to known nutritional amino acid essentiality/nonessentiality but revealed differences in labeling among the nonessential amino acids: most notable was that proline accretion was derived entirely from the diet. Feeding uniformly 13C-labeled algal protein and recovering and analyzing de novo-synthesized protein provides a useful method to examine amino acid metabolism and determine conditional amino acid essentially in vivo.

Journal Article↗
PubMed2001

Retinoblastoma protein: combating algal bloom.

The discovery of a homolog of the retinoblastoma protein (Rb) in a single-celled eukaryote--the alga Chlamydomonas--promises new and surprising insights into Rb's function in cell-cycle regulation.

Algal Proteins↗
PubMed2006

Micro-algae as a source of protein.

About five decades ago, the mass production of certain protein-rich micro-algae was considered as a possibility to close the predicted so called "protein gap". Comprehensive analyses and nutritional studies have demonstrated that these algal proteins are of high quality and comparable to conventional vegetable proteins. However, due to high production costs as well as technical difficulties to incorporate the algal material into palatable food preparations, the propagation of algal protein is still in its infancy. To date, the majority of micro-algal preparations are marketed as health food, as cosmetics or as animal feed.

Algal Proteins↗
PubMed1980

[Effect of gum guar in the diet on the utilization of 14C-labeled protein and protein hydrolysates in young rats].

Beginning on the 25th day of life and for 2 weeks therafter Sprague-Dawley rats were fed a casein diet containing 10% of gum guar. The animals were given. 14C algal protein or 14C algal protein hydrolysate by stomach tube and the radioactivity in some tissues and tissue proteins was determined 3 h after the application. Radioactivity in blood and in respiratory CO2 was measured up to 3 h and 6 h, respectively, after the application. The results indicate no effect of gum guar on the utilization of the protein or of the amino acids of the protein hydrolysate.

Animals↗
PubMed1978

Interchangeable copper and iron proteins in algal photosynthesis. Studies on plastocyanin and cytochrome c-552 in Chlamydomonas.

The interrelation of the copper protein plastocyanin, and a soluble c-type cytochrome, c-552, in photosynthetic electron transport has been studied in the genus Chlamydomonas. With C. reinhardtii the plastocyanin: cytochrome c-552 ratio could be changed from 300:1 less than 1:16 simply by omitting copper from the medium, without any other detectable change. Plastocyanin was indetectable in a second species, C. mundana, for which the cytochrome c-552 level was always very high. The properties of Levine's C. reinhardtii mutant lacking plastocyanin, ac-208, were studies and it was found that the photosynthetic capabilities of a suppressed phenotype and suppressed genotype could be explained by reference to the cytochrome c-552 levels. Both proteins were successfully used in reconstitution experiments with chloroplast fragments. Both showed very fast kinetics for reduction by purified Chlamydomonas cytochrome f, but the rate of electron transfer from one to the other was much slower. It is concluded that they constitute an interchangeable pair, and the rationale for this and possible analogies are both discussed.

Biological Evolution↗
PubMed2005

A novel protein C-phycocyanin plays a crucial role in the hypocholesterolemic action of Spirulina platensis concentrate in rats.

This study was designed to clarify the mechanisms of the hypocholesterolemic action of Spirulina platensis concentrate (SPC) and identify the novel hypocholesterolemic protein derived from SPC. We investigated the effects of casein or SPC on the solubility of cholesterol, taurocholate binding capacity in vitro, cholesterol absorption in Caco-2 cells, and cholesterol metabolism in rats for 10 d. We also evaluated the effects of SPC, C-phycocyanin (PHY), and PHY residue on cholesterol metabolism in rats fed a high-cholesterol diet for 5 d, and SPC or SPC-acetone extract for 10 d. SPC had a significantly greater bile acid-binding capacity than casein in vitro. Micellar cholesterol solubility and cholesterol uptake by Caco-2 cells was significantly lower in the presence of SPC compared with casein. Fecal excretion of cholesterol and bile acids was significantly greater in rats fed the SPC-supplemented diet than in those fed the casein control diet. Serum and liver cholesterol concentrations were significantly lower in rats fed SPC than in those fed casein. Thus, the hypocholesterolemic action of SPC may involve the inhibition of both jejunal cholesterol absorption and ileal bile acid reabsorption. Although no studies to date have found a hypocholesterolemic protein among the algal proteins, we report here the discovery of a hypocholesterolemic effect in the novel protein C-phycocyanin. This study provides the first direct evidence that PHY, a novel hypocholesterolemic protein derived from Spirulina platensis, can powerfully influence serum cholesterol concentrations and impart a stronger hypocholesterolemic activity than SPC in animals.

Acetone↗
PubMed2001

Gelation of edible blue-green algae protein isolate (Spirulina platensis Strain Pacifica): thermal transitions, rheological properties, and molecular forces involved.

Proteins isolated from blue-green algae Spirulina platensis strain Pacifica were characterized by visible absorption, differential scanning calorimetry (DSC), viscometry, and dynamic oscillatory rheological measurements. Unique thermal unfolding, denaturation, aggregation, and gelation of the algal protein isolate are presented. DSC analysis showed that thermal transitions occur at about 67 and 109 degrees C at neutral pH. Calcium chloride stabilized the quaternary structure against denaturation and shifted the transitions at higher temperatures. Viscometric studies of Spirulina protein isolate as a function of temperature showed that the onset of the viscosity increase is closely related to the dissociation-denaturation process. Lower viscosities were observed for the protein solutions dissolved at pH 9 due to an increased protein solubility. Solutions of Spirulina protein isolate form elastic gels during heating to 90 degrees C. Subsequent cooling at ambient temperatures caused a further pronounced increase in the elastic moduli and network elasticity. Spirulina protein isolate has good gelling properties with fairly low minimum critical gelling concentrations of about 1.5 and 2.5 wt % in 0.1 M Tris buffer, pH 7, and with 0.02 M CaCl(2) in the same buffer, respectively. It is suggested that mainly the interactions of exposed hydrophobic regions generate the molecular association, initial aggregation, and gelation of the protein isolate during the thermal treatment. Hydrogen bonds reinforce the network rigidity of the protein on cooling and further stabilize the structure of Spirulina protein gels but alone are not sufficient to form a network structure. Intermolecular sulfhydryl and disulfide bonds were found to play a minor role for the network strength of Spirulina protein gels but affect the elasticity of the structures formed. Both time and temperature at isothermal heat-induced gelation within 40-80 degrees C affect substantially the network formation and the development of elastic modulus of Spirulina protein gels. This is also attributed to the strong temperature dependence of hydrophobic interactions. The aggregation, denaturation, and gelation properties of Spirulina algal protein isolate are likely to be controlled from protein-protein complexes rather than individual protein molecules.

Bacterial Proteins↗
PubMed2004

The oxygen evolving enhancer protein 1 (OEE) of photosystem II in green algae exhibits thioredoxin activity.

A thioredoxin-like chloroplast protein of the fructosebisphosphatase-stimulating f-type, but with an unusually high molecular mass of 28 kDa has previously been identified and purified to homogeneity in a fractionation scheme for resolution of the acid- and heat-stable, regular-size (12kDa) thioredoxins of the unicellular green algae, Scenedesmus obliquus. An apparently analogous protein of 26 kDa was described in a cyanobacterium, Anabaena sp., but no such large thioredoxin species f exists in the thioredoxin profiles of higher plants. The structure of the 28 kDa protein, which had been envisaged to represent a precursor, or fusion product of the two more specialized, common chloroplast thioredoxins f and m has now been determined by amino acid sequencing. Although it exhibits virtually all the properties and enzyme-modulating activities of a thioredoxin proper this algal protein, surprisingly, does not belong to the thioredoxin family of small redox proteins but is identical with OEE (oxygen evolving enhancer) protein 1, an auxiliary component of the photosystem II manganese cluster. Extracts of Chlorella vulgaris and Chlamydomonas reinhardtii also contain heat-stable protein fractions of 23-26 kDa capable of specifically stimulating chloroplast fructosebisphosphatase in vitro. In contrast, OEE protein 1 from spinach is not able to modulate FbPase or NADP malate dehydrogenase from spinach chloroplasts. A dual function of the OEE protein in algal photosynthesis is envisaged.

Algal Proteins↗
PubMed2005

Light-stimulated neurons.

Expression of an algal protein in neurons provides a means of selectively photostimulating individual neurons with unprecedented speed and reproducibility.

Algal Proteins↗
PubMed2006

Channelrhodopsin-2 and optical control of excitable cells.

Electrically excitable cells are important in the normal functioning and in the pathophysiology of many biological processes. These cells are typically embedded in dense, heterogeneous tissues, rendering them difficult to target selectively with conventional electrical stimulation methods. The algal protein Channelrhodopsin-2 offers a new and promising solution by permitting minimally invasive, genetically targeted and temporally precise photostimulation. Here we explore technological issues relevant to the temporal precision, spatial targeting and physiological implementation of ChR2, in the context of other photostimulation approaches to optical control of excitable cells.

Algal Proteins↗
PubMed2005

Millisecond-timescale, genetically targeted optical control of neural activity.

Temporally precise, noninvasive control of activity in well-defined neuronal populations is a long-sought goal of systems neuroscience. We adapted for this purpose the naturally occurring algal protein Channelrhodopsin-2, a rapidly gated light-sensitive cation channel, by using lentiviral gene delivery in combination with high-speed optical switching to photostimulate mammalian neurons. We demonstrate reliable, millisecond-timescale control of neuronal spiking, as well as control of excitatory and inhibitory synaptic transmission. This technology allows the use of light to alter neural processing at the level of single spikes and synaptic events, yielding a widely applicable tool for neuroscientists and biomedical engineers.

Action Potentials↗
PubMed1994

The extrinsic proteins of photosystem II in photosynthetic organisms: distribution, properties and evolutionary implications.

Photosystem II from higher plant chloroplasts contains extrinsic proteins of molecular weights 33, 23 and 16 kDa. Cyanobacteria, which are thought to be closely related to the evolutionary progenitor of chloroplasts, have a protein homologous to the largest of these, but lack homologues of the smaller ones. Here we report immunological evidence for the occurrence of the 33 kDa extrinsic protein in red and chromophyte algae and its absence from anoxygenic photosynthetic bacteria. The 23 kDa protein was absent from all three groups. The red algal protein was found to be hydrophilic and rather more loosely associated with the thylakoid membrane than its higher plant equivalent. These findings support an origin for all plastids among the oxygenic prokaryotes, in contrast to the phylogeny inferred from ribulose bisphosphate carboxylase-oxygenase sequence data.

Biological Evolution↗