A possible new mechanism of temperature dependence of electron transfer in photosynthetic systems

A new theory for the electron transfer by the non-adiabatic process is formulated taking into account the origin shift and the frequency change of the vibration. The resultant formulas are quite similar to those of Jortner (Jortner, J. (1976) J. Chem. Phys. 64, 4860–4867) except that the free energy gap ΔG is used instead of the energy gap ΔE. By applying this theory to the photosynthetic electron transfer, the role of the remarkable temperature dependence of the electron transfer from cytochrome to P⁺ in Chromatium vinosum and the experimental data were reproduced very well using a small value of the coupling strength in contrast with the previous theory. This implies that proteins play a role to exclude many of the solvent molecules from the region of the electron transfer reaction between the donor and acceptor molecules. The negative activation process in the back electron transfer from Q^?_A to P⁺, the very slow back electron transfer from I^? to P⁺ and the solvent isotope effect on the cytochrome oxidation are also successfully explained by this new theory. It is shown that even a qualitative conclusion as to the molecular parameters obtained from the temperature dependence of the electron transfer is different between the present theory and that of Jortner.     

Immunoelectron microscopic study on interactions of noninfectious sendai virus and murine cells.

The early interactions of LLC-MK2 cell-grown noninfectious Sendai virus and a murine cell line, P815 mastocytoma ascitic cells, were studied by electron microscopy, using the ferritin-conjugated antibody technique with anti-virus glycoprotein serum. For comparison, the interactions of egg-grown infectious Sendai virus with the same cells were also examined. When noninfectious virus was adsorbed to the cells in the cold, the cell membranes become partially invaginated at the site of contact of adsorbed virions, but ferritin-conjugated antibodies did not penetrate into the areas of envelope-cell membrane association. This pattern of virus attachment was similar to that of infectious virus attachment. Upon subsequent incubation at 37 degrees C, most of the adsorbed noninfectious virions were taken into cytoplasmic vesicles and then degraded, although a few virions remained attached to the cell membrane. No evidence of fusion of envelopes of noninfectious virions was obtained. On the other hand, envelopes of infectious virions fused with the cell membrane, and the transferred viral antigens diffused on the cell surfaces and then decreased in number.     

Establishment of Autoantibody-Producing Cell Lines from Peripheral Blood Lymphocytes of Patients with Systemic Lupus Erythematosus

Autoantibody-producing B cell lines were established from peripheral blood lymphocytes of patients with systemic lupus erythematosus. Peripheral blood lymphocytes obtained from five of seven patients were successfully transformed by Epstein-Barr virus. Two of four established B lymphoblastoid cell lines examined in this study produced anti-nuclear factor antibodies and one of them produced anti-single-stranded DNA and anti-double-stranded DNA antibodies. These results indicate that B cell clones committed to self antigens are transformed by Epstein-Barr virus and continue to produce autoantibodies. In order to establish a monoclonal autoantibody-producing B cell line, the cells were cloned by a limiting dilution method. The data suggest that it is possible to establish a monoclonal autoantibody-producing B cell line by the combination of transformation of B cells by Epstein-Barr virus and extensive cloning.     

Contribution of microsomal cytochrome b5 electron transport system coupled with Δ5-3β-hydroxysteroid dehydrogenase to androgen synthesis from progesterone

Cytochromes P-450 and $\text{b}$₅ were observed in the microsomal fraction of interstitial tissue of rat testes. Microsomal cytochrome $\text{b}$₅ was reduced by the NADH coupled with the activities of Δ⁵-3β-hydroxysteroid dehydrogenase with Δ⁵-Δ⁴ isomerase through conversion of pregnenolone to progesterone. Activities of NADPH-supported 17α-hydroxylase and C-17-C-20 lyase which converted progesterone to androstenedione were stimulated by either the presence of NADH or the oxidative reaction by the dehydrogenase upon Δ⁵-3β-hydroxysteroids. Androstenedione production enhanced by the reaction of the dehydrogenase was decreased by addition of the antibody against NADH-cytochrome $\text{b}$₅ reductase which was purified from rat hepatic microsomes, suggesting the active participation of cytochrome $\text{b}$₅ in the androgen synthesis.     

Effect of glucose on protein phosphorylation in rat pancreatic islets

Isolated rat pancreatic islets, incubated in the presence of extracellular ³²Pi to steady state ³²P incorporation into cellular phosphopeptides, were exposed to glucose for 10 min. Glucose (16.7 mM) significantly stimulated the phosphorylation of six phosphoproteins with molecular weights of 15,000, 35,000, 49,000, 64,000, 93,000 and 138,000. Mannoheptulose (16.7 mM) markedly inhibited glucose-stimulated phosphorylation of these six phosphoproteins. This protein phosphorylation might be important in mediating glucose-stimulated insulin release.     

Fertilizability of cryopreserved zona-free hamster ova

Mature unfertilized ova from superovulated hamsters were freed from all investments and frozen at ?50°C. They were cooled at about 1°C/min to 0°C then at 0.8° to 0.6°C/min to ?50°C. At 0°C, dimethyl sulfoxide was added to a final concentration of 1.25 M. The ova were stored at ?50°C for up to four months. Thawing was performed at 2–4°C/min and followed by several washes with insemination medium. Approximately 90% of the ova were normal in appearance after thawing. The frozen and thawed ova with normal appearance could be penetrated by hamster or human spermatozoa at a rate comparable to unfrozen controls. The ability of hamster ova to tolerate storage at a relatively convenient temperature (?50°C) for long periods (tested for up to four months) makes possible their shipment at low cost to institutions lacking this resource. There they can be used for basic biological studies of sperm–egg interaction or in the clinical assessment of human sperm quality.     

Bacterial oxidation of polyethylene glycol.

The metabolism of polyethylene glycol (PEG) was investigated with a synergistic, mixed culture of Flavobacterium and Pseudomonas species, which are individually unable to utilize PEGs. The PEG dehydrogenase linked with 2,6-dichlorophenolindophenol was found in the particulate fraction of sonic extracts and catalyzed the formation of a 2,4-dinitrophenylhydrazine-positive compound, possibly an an aldehyde. The enzyme has a wide substrate specificity towards PEGs: from diethylene glycol to PEG 20,000 Km values for tetraethylene glycol (TEG), PEG 400, and PEG 6,000 were 11, 1.7, and 15 mM, respectively. The metabolic products formed from TEG by intact cells were isolated and identified by combined gas chromatography-mass spectrometry as triethylene glycol and TEG-monocarboxylic acid plus small amounts of TEG-dicarboxylic acid, diethylene glycol, and ethylene glycol. From these enzymatic and analytical data, the following metabolic pathway was proposed for PEG: HO(CH2CH2O)nCH2CH2OH leads to HO(CH2CH2O)nCH2CHO leads to HO(CH2CH2O)nCH2COOH leads to HO(CH2CH2O)n-1CH2CH2OH.     

Adenine nucleotide metabolism of blood platelets. IX. Time course of secretion and changes in energy metabolism in thrombin-treated platelets.

Changes in the energy metabolism of washed human platelets were compared with the kinetics of secretion induced by thrombin (5 units/ml). A 50% decrease in the level of metabolic ATP (3H-labelled), which was essentially complete in 30s, was matched in rate by adenine nucleotide secretion from storage in dense granules. Incubation of platelets with antimycin before thrombin addition increased the rate of fall in metabolic ATP, but did not affect the rate of adenine nucleotide secretion. beta-N-Acetylglucosaminidase secretion, which was slower than adenine nucleotide secretion in control platelets, was noticeably inhibited by antimycin, confirming previous reports that different regulatory mechanisms exist for dense and alpha-granule secretion. The rates of rephosphorylation of metabolic ADP to ATP via glycolysis and oxidative phosphorylation were estimated by measuring lactate production and O2 consumption in resting and thrombin-stimulated platelets and compared to the level of metabolic ATP (9-10 nmol/mg of platelet protein in the resting state). The rate of ATP production was stimulated at least two fold from 12 nmol to 24 nmol/min/mg within seconds of thrombin addition. This increased rate was maintained over the observed period of 5 min although the level of metabolic ATP had decreased to 4-5 nmol/mg within 30 s; the turnover of the remaining metabolic ATP thus increased four fold over the resting state although the actual stimulation of energy production was only two fold.     

Enzymatic synthesis of poly-β-hydroxybutyrate inZoogloea ramigera

The enzyme activity synthesizing poly--hydroxybutyrate (PHB) was mainly localized in the PHB-containing particulate fraction ofZoogloea ramigera I-16-M, when it grew flocculatedly in a medium supplemented with glucose. On the other hand, the enzyme activity remained in the soluble fraction, when the bacterium grew dispersedly in a glucose-starved medium.The soluble PHB synthase activity became associated with the particulate fraction as PHB synthesis was initiated on the addition of glucose to the dispersed culture. Conversely, the enzyme activity was released from the PHB-containing granules to the soluble fraction when the flocculated culture was kept incubated without supplementing the medium with glucose.PHB synthase was also incorporated into the newly formed PHB fraction when partially purified soluble PHB synthase was incubated withd(-)--hydroxybutyryl CoA in vitro.Although attempts to solubilize the particulate enzyme were unsuccessful, and the soluble enzyme became extremely unstable in advanced stages of purification, both PHB synthases had the same strict substrate specificity ford(-)--hydroxybutyryl CoA, and showed the same pH optimum at 7.0.Non-Standard Abbreviations PHB poly--hydroxybutyrate     

Adenine nucleotide metabolism of blood platelets IX. Time course of secretion and changes in energy metabolism in thrombin-treated platelets

Changes in the energy metabolism of washed human platelets were compared with the kinetics of secretion induced by thrombin (5 units/ml). A 50% decrease in the level of metabolic ATP (³H-labelled), which was essentially complete in 30 s, was matched in rate by adenine nucleotide secretion from storage in dense granules. Incubation of platelets with antimycin before thrombin addition increased the rate of fall in metabolic ATP, but did not affect the rate of adenine nucleotide secretion. β-N-Acetylglucosaminidase secretion, which was slower than adenine nucleotide secretion in control platelets, was noticeably inhibited by antimycin, confirming previous reports that different regulatory mechanisms exist for dense and α-granule secretion. The rates of rephosphorylation of metabolic ADP to ATP via glycolysis and oxidative phosphorylation were estimated by measuring lactate production and O₂ consumption in resting and thrombin-stimulated platelets and compared to the level of metabolic ATP (9–10 nmol/mg of platelet protein in the resting state). The rate of ATP production was stimulated at least two fold from 12 nmol to 24 nmol/min/mg within seconds of thrombin addition. This increased rate was maintained over the observed period of 5 min although the level of metabolic ATP had decreased to 4–5 nmol/mg within 30 s; the turnover of the remaining metabolic ATP thus increased four fold over the resting state although the actual stimulation of energy production was only two fold.