Chlorophyll isolation,structure and function: major landmarks of the early history of research in the Russian Empire and the Soviet Union

This paper covers major events of the early history of chlorophyll research in the Russian Empire and the Soviet Union from 1771 until 1952, when the modern period of studies on photosynthesis began in full swing. Short biographical sketches of key scientists, reviews of their major research contributions and some selected photographs are included. This revised version was published online in August 2006 with corrections to the Cover Date.     

Period four oscillations in chlorophyll a fluorescence

The discovery of period four oscillations of the fluorescence yield under flashing light demonstrated that not only the redox state of the Photosystem II (PS II) electron acceptor Q_A, but also the oxygen evolving cycle (described by the S states) modulates the fluorescence yield of chlorophyll (Chl). The positive charges accumulated on the donor side of PS II act on the fluorescence yield (measured in the Q_A ⁻ state during a strong flash) through the concentration of the quencher P₆₈₀ ⁺, the oxidized form of PS II reaction center Chl a. However, the period four oscillations of the fluorescence yield detected 1 s after a strong flash (in the P₆₈₀Q_A state) have not yet been fully explained. This revised version was published online in June 2006 with corrections to the Cover Date.     

Photosynthesis research in India: transition from yield physiology into molecular biology

Photosynthesis research in India can be traced back several thousand years, with the mention of the Sun energizing the plants, which form food for all living creatures on the earth (from the Mahabharata, the great epic, ca. 2600 B.C.) and the report of Sage Parasara (ca. 100 B.C.) on the ability of plants to make their own food, due to their pigments. With the pioneering studies by Sir Jagdish Chandra Bose, work on photosynthesis proceeded steadily during the first half of the 20th century. Some of the classic reports during this period are: malate metabolism in Hydrilla, spectrophotometric estimation of chlorophylls, importance of spectral quality for photosynthesis – an indication of two photosystems, photoinactivation of photosynthesis, and importance of flag leaf photosynthesis to grain yield. After the 1960s, there was a burst of research in the areas of physiology and biochemistry of carbon assimilation and photochemistry. A significant transition occurred, before the beginning of new millennium, into the area of molecular biology of chloroplasts, regulation of photosynthesis and stress tolerance. Future research work in India is geared to focus on the following aspects of photosynthesis: elucidation/analysis of genes, molecular biology/evolution of enzymes, development/use of transgenics and modeling. This revised version was published online in August 2006 with corrections to the Cover Date.     

Structural,biochemical and biophysical characterization of four oxygen-evolving Photosystem II preparations from spinach

Four procedures utilizing different detergent and salt conditions were used to isolate oxygen-evolving Photosystem II (PS II) preparations from spinach thylakoid membranes. These PS II preparations have been characterized by freeze-fracture electron microscopy, SDS-polyacrylamide gel electrophoresis, steady-state and pulsed oxygen evolution, 77 K fluorescence, and room-temperature electron paramagnetic resonance. All of the O₂-evolving PS II samples were found to be highly purified grana membrane fractions composed of paired, appressed membrane fragments. The lumenal surfaces of the membranes and thus the O₂-evolving enzyme complex, are directly exposed to the external environment. Biochemical and biophysical analyses indicated that all four preparations are enriched in the chlorophyll $\text{a}\text{b-}\text{light-harvesting}$ complex and Photosystem II, and depleted to varying degrees in the stroma-associated components, Photosystem I and the CF₁-ATPase. The four PS II samples also varied in their cytochrome f content. All preparations showed enhanced stability of oxygen production and oxygen-rate electrode activity compared to control thylakoids, apparently promoted by low concentrations of residual detergent in the PS II preparations. A model is presented which summarizes the effects of the salt and detergent treatments on thylakoid structure and, consequently, on the configuration and composition of the oxygen-evolving PS II samples.     

A new protein from human plasma lipoproteins: isolation and partial characterization of apolipoprotein G]

A new apolipoprotein has been identified in VHDL1 and in HDL. This protein is immunologically distinct from already isolated apoproteins. It was isolated by column chromatography on hydroxylapatite. In polyacrylamide gel electrophoresis, its mobility is very close to that of apo D. The amino acid composition differs from those of the well characterized polypeptides of the human plasma lipoproteins. It contains glucosamine. The apparent molecular weight is 72 000 +/- 2 000 in the presence and absence of reducing agent. According to the ABCDEF nomenclature, this protein can be named apolipoprotein G (apo G). It is present in a lipoprotein distinct from the lipoproteins A and D among the VHDL1 : this new lipoprotein can be named lipoprotein G (LPG).     

Adenine recognition: a motif present in ATP-, CoA-, NAD-, NADP-, and FAD-dependent proteins.

Adenosine triphosphate (ATP) plays an essential role in energy transfer within the cell. In the form of NAD, adenine participates in multiple redox reactions. Phosphorylation and ATP-hydrolysis reactions have key roles in signal transduction and regulation of many proteins, especially enzymes. In each cell, proteins with many different functions use adenine and its derivatives as ligands; adenine, of course, is present in DNA and RNA. We show that an adenine binding motif, which differs according to the backbone chain direction of a loop that binds adenine (and in one variant by the participation of an aspartate side-chain), is common to many proteins; it was found from an analysis of all adenylate-containing protein structures from the Protein Data Bank. Indeed, 224 protein-ligand complexes (86 different proteins) from a total of 645 protein structure files bind ATP, CoA, NAD, NADP, FAD, or other adenine-containing ligands, and use the same structural elements to recognize adenine, regardless of whether the ligand is a coenzyme, cofactor, substrate, or an allosteric effector. The common adenine-binding motif shown in this study is simple to construct. It uses only (1) backbone polar interactions that are not dependent on the protein sequence or particular properties of amino acid side-chains, and (2) nonspecific hydrophobic interactions. This is probably why so many different proteins with different functions use this motif to bind an adenylate-containing ligand. The adenylate-binding motif reported is present in "ancient proteins" common to all living organisms, suggesting that adenine-containing ligands and the common motif for binding them were exploited very early in evolution. The geometry of adenine binding by this motif mimics almost exactly the geometry of adenine base-pairing seen in DNA and RNA.     

In-vivo hyperglycemic,antioxidant, histopathological changes,and simultaneous measurement of kaempferol verified by high-performance thin layer chromatography of Setaria italica in streptozotocin -induced diabetic rats

BackgroundSetaria italica (common name- foxtail, kangni) is one of the major food crops which is prominently cultivated in southern regions of India and in certain regions of Uttar Pradesh. Besides the crop’s consumption as a general source of carbohydrate rich cereal, the seeds of the crop are comprised of more fiber. So, it is recommended to add in the dietary supplementation of the diabetic people across the country.ObjectiveIn this paper, it intends to investigate the antidiabetic activity and antioxidant activity of S. italica (foxtail millet) seeds in diabetic rats.MethodsThe six genotypes of foxtail millets (S. italica) namely Kangni-1, Kangni-4, Kangni-5, Kangni-6, Kangni-7 & Kangni-10 respectively were subjected to in vitro investigations via. comprehensive metabolic panel (CMP) involving blood glucose study, Kidney & Liver function test, and antioxidant study (Catalase test; Glutathione S-transferase (GST); Superoxide Dismutase (SOD); glutathione (GSH); hiobarbituric acid reactive substances (TBARS) & Glutathione peroxidase (GPx) and were performed in vivo animal investigations in Wistar rats. The STZ induced diabetic rats were fed with doses of different S. italica seed aqueous extract to evaluate its anti-hyperglycemic activity by oral administration of SISAE. Further, it was compared with Glibenclamide which acts as one of the standard oral hypoglycemic agents.ResultsFrom achieved outcomes, a significant fall of blood glucose level (70%) produced 300 mg SISAE/kg b.w. after 6 h of extract administration. However, no change could be produced by these doses of the SISAE in normal rats’ blood glucose levels. A significant fall in glucose level along with significant glycemic control by lower HbA1c levels was observed in diabetic treated rats after 3 weeks of treatment with 300 mg of SISAE/kg b.w./day when comparing to untreated diabetic rats. Among these five genotypes of S. italica, the differences in the glycemic index were found. a significant fall could be found in blood glucose levels of Wistar rats, when every experimental rat was incorporating with the extract of different genotypes of Setaria italica L. Beauv than the rats treated with Glibenclamide in every 7 days of interval. The level of catalase, SOD, GST, GPx, GSH and TBARS showed variation while the rats were fed with the extract of S. italica in the liver test of rats. In kidney function test, the result shows that there is significant relationship between foxtail extract and kidney function of STZ induced diabetes rats. They show the change in their serum creatinine level, serum urea and serum uric acid.ConclusionThe result obtained from the study shows that the extract of S. italica seeds is capable for the hypolipidemic and antihyperglycemic activities, thereby, they serve as one of the good sources for herbal medicinal items.