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Articles 271 - 290 of 290

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Chloroplast Thylakoid Protein Phosphatase Is A Membrane Surface-Associated Activity, Gongqin Sun, Doreen Bailey, Michael W. Jones, John Markwell Jan 1989

Chloroplast Thylakoid Protein Phosphatase Is A Membrane Surface-Associated Activity, Gongqin Sun, Doreen Bailey, Michael W. Jones, John Markwell

Biochemistry -- Faculty Publications

Chloroplast thylakoid protein phosphatase activity was measured using 32P-labeled histone as an exogenous substrate and an assay of the 32P released involving formation of a phosphomolybdate complex and organic extraction. The activity was liberated from wheat (Triticum aestivum) thylakoids by washing the membranes in NaCI-containing solutions followed by centrifugation. The liberated phosphatase activity had a pH optimum of approximately 6.75, was inhibited by addition of 10 millimolar EDTA or EGTA, and was stimulated by addition of millimolar amounts of dithiothreitol, magnesium, manganese, or calcium ions. The rate of thylakoid protein dephosphorylation was decreased following liberation of a ...


Role Of Metabolites In The Reversible Light Activation Of Pyruvate,Orthophosphate Dikinase In Zea Mays Mesophyll Cells In Vivo, Chrissi A. Roeske, Raymond Chollet Jan 1989

Role Of Metabolites In The Reversible Light Activation Of Pyruvate,Orthophosphate Dikinase In Zea Mays Mesophyll Cells In Vivo, Chrissi A. Roeske, Raymond Chollet

Biochemistry -- Faculty Publications

Whole leaf and mesophyll cell concentrations of pyruvate, phosphoenolpyruvate (PEP), ATP, and ADP were determined in Zea mays during the reversible light activation of pyruvate, orthophosphate dikinase in vivo. Mesophyll cell levels of the four metabolites were estimated by extrapolation from values in freeze-quenched leaf samples that were fractionated by differential filtration through nylon mesh nets (adapted from M Stitt, HW Heldt [1985] Planta 164: 179-188). During the 3 minutes required for complete light activation of dikinase, pyruvate levels in the mesophyll cell decreased (from 166 ± 15 to 64 ± 10 nanomoles per milligram of chlorophyll [nmol/mg Chi]) while PEP ...


Nucleotide Sequence Of The Fadr Gene, A Multifunctional Regulator Of Fatty Acid Metabolism In Escherichia Coli, Concetta C. Dirusso Jan 1988

Nucleotide Sequence Of The Fadr Gene, A Multifunctional Regulator Of Fatty Acid Metabolism In Escherichia Coli, Concetta C. Dirusso

Biochemistry -- Faculty Publications

The Escherichia coli fadR gene is a multifunctional regulator of fatty acid

and acetate metabolism. In the present work the nucleotide sequence of the

1.3 kb DNA fragment which encodes FadR has been determined. The coding

sequence of the fadR gene is 714 nucleotides long and is preceded by a typical

E. coli ribosome binding site and is followed by a sequence predicted to be

sufficient for factor-independent chain termination. Primer extension experiments

demonstrated that the transcription of the fadR gene initiates with an

adenine nucleotide 33 nucleotides upstream from the predicted start of

translation. The derived fadR peptide ...


The Binding Of Host-Selective Toxin Analogs To Mitochondria From Normal And 'Texas' Male Sterile Cytoplasm Maize, Kurt A. Frantzen, J. M. Daly, Herman W. Knoche Jan 1987

The Binding Of Host-Selective Toxin Analogs To Mitochondria From Normal And 'Texas' Male Sterile Cytoplasm Maize, Kurt A. Frantzen, J. M. Daly, Herman W. Knoche

Biochemistry -- Faculty Publications

Tritium-labeled toxin analogs were prepared by reduction with NaB3H4 of either the toxin from Helminthosporium maydis race T or a toxin component from Phyllosticta maydis. These reduced analogs had high radiochemical specific activities, high biological activities, and plant specificities identical to the native toxins. A filtration assay was developed to test the binding of these labeled analogs to isolated- mitochondria. Binding was not energy dependent nor was there measurable matrical uptake. The analogs were shown to be lipophilic, a characteristic which gave rise to considerable nondisplaceable binding. Under conditions limiting nondisplaceable binding, -the displaceable binding was shown ...


In Vitro Phosphorylation Of Maize Leaf Phosphoenolpyruvate Carboxylase, Raymond J. A. Budde, Raymond Chollet Jan 1986

In Vitro Phosphorylation Of Maize Leaf Phosphoenolpyruvate Carboxylase, Raymond J. A. Budde, Raymond Chollet

Biochemistry -- Faculty Publications

Autoradiography of total soluble maize (Zea mays) leaf proteins incubated with 32P-labeled adenylates and separated by denaturing electrophoresis revealed that many polypeptides were phosphorylated in vitro by endogenous protein kinase(s). The most intense band was at 94 to 100 kilodaltons and was observed when using either [γ -32P]ATP or [β-32P]ADP as the phosphate donor. This band was comprised of the subunits of both pyruvate, Pi dikinase (PPDK) and phosphoenolpyruvate carboxylase (PEPCase). PPDK activity was previously shown to be dark/light-regulated via a novel ADP-dependent phosphorylation/Pi-dependent dephosphorylation of a threonyl residue. The identity of ...


Cloning And Characterization Of A Gene (Fadr) Involved In Regulation Of Fatty Acid Metabolism In Escherichia Coli, Concetta C. Dirusso, William D. Nunn Jan 1985

Cloning And Characterization Of A Gene (Fadr) Involved In Regulation Of Fatty Acid Metabolism In Escherichia Coli, Concetta C. Dirusso, William D. Nunn

Biochemistry -- Faculty Publications

The regulatory gene fadR has been previously characterized by classical genetic means as a diffusible protein which exerts negative control over fatty acid degradation and acetate metabolism. fadR has also been implicated in the regulation of unsaturated fatty acid biosynthesis. To facilitate the identification of the product of the fadR gene and to study the mechanism by which this multifunctional regulatory gene exerts its control, we cloned a segment of DNA containing the fadR gene in the phage vector λL47. Subsequent subcloning of a segment of the chromosomal DNA from the λfadR+ phage into various plasmid vectors resulted in the ...


Reduction Of Ferric Leghemoglobin In Soybean Root Nodules, Keuk-Ki Lee, Robert V. Klucas Jan 1984

Reduction Of Ferric Leghemoglobin In Soybean Root Nodules, Keuk-Ki Lee, Robert V. Klucas

Biochemistry -- Faculty Publications

Reduction of ferric leghemoglobin to ferrous leghemoglobin in soybean nodules (Glycine max [L.] Meff. cv Woodworth) was studied using a spectrophotometer equipped with an in-cell space diffuse reflectance accessory. Nodule slices prepared and scanned under nitrogen gas showed a ferrous leghemoglobin absorption spectrum. Nodule slices equilibrated with 100% O2 or air exhibited two absorption bands characteristic of oxygenated leghemoglobin. The addition of CO shifted those bands to CO leghemoglobin absorption bands. Potassium ferricyanide was not effective in oxidizing ferrous to feffic leghemoglobin in nodule slices. However, ferric leghemoglobin was formed by treating the nodule slices with hydroxylamine, and this ...


Proteolytic Activity In Soybean Root Nodules: Activity In Host Cell Cytosol And Bacteroids Throughout Physiological Development And Senescence, Nancy E. Pfeiffer, Cecilia M. Torres, Fred W. Wagner Jan 1983

Proteolytic Activity In Soybean Root Nodules: Activity In Host Cell Cytosol And Bacteroids Throughout Physiological Development And Senescence, Nancy E. Pfeiffer, Cecilia M. Torres, Fred W. Wagner

Biochemistry -- Faculty Publications

Root nodules were harvested from chamber-grown soybean (Glycine max L. Merril cv Woodworth) plants throughout development. Apparent nitrogenase activity (acetylene reduction) peaked before seeds began to develop, but a significant amount of activity remained as the seeds matured. Nodule senescence was defined as the period in which residual nitrogenase activity was lost. During this time, soluble protein and leghemoglobin levels in the host cell cytosol decreased, and proteolytic activity against azocasein increased. Degradative changes were not detected in bacteroids during nodule senescence. Total soluble bacteroid protein per gram of nodule remained constant, and an increase in proteolytic activity in bacteroid ...


Reversible Dark-Induced Senescence Of Soybean Root Nodules, N. E. Pfeiffer, Nasir S.A. Malik, Fred W. Wagner Jan 1983

Reversible Dark-Induced Senescence Of Soybean Root Nodules, N. E. Pfeiffer, Nasir S.A. Malik, Fred W. Wagner

Biochemistry -- Faculty Publications

Nodule senescence was induced in intact soybean Glycine max. (L.) Merr., cv Woodworth plants by an 8-day dark treatment. Dark-induced senescence resulted in the complete loss of acetylene reduction activity, a 67% loss of total soluble protein, and an almost complete loss in total leghemoglobin of nodule extracts. Isoelectric focusing gels demonstrated a preferential loss of certain proteins, which was correlated with an increase in endoprotease specific activity toward azocasein. Nodules were completely green after the 8-day dark treatment. If plants were returned to a normal photoperiod after 8 days in the dark, nodules recovered from the dark treatment in ...


Peptidohydrolases Of Soybean Root Nodules, Nasir S. A. Malik, N. E. Pfeiffer, D. R. Williams, Fred W. Wagner Jan 1981

Peptidohydrolases Of Soybean Root Nodules, Nasir S. A. Malik, N. E. Pfeiffer, D. R. Williams, Fred W. Wagner

Biochemistry -- Faculty Publications

Nodule extracts prepared from Glycine max var Woodworth possessed endopeptidase, aminoptidase, and carboxypeptidase actiities. Three distinct endopeptidase activities could be resolved by disc-gel electrophoresis at pH 8.8. According to their order of increasing electrophoretic mobility, the first of these enzymes hydrolyzed azocasein and n-benzoyl-LLeu-β-naphthylamide, while the second hydrolyzed n-benzoyl-L-Arg-/8- naphthylamine (Bz-L-Arg-/βNA), n-benzoyl-L-Arg-β-nitroanilide (Bz-L-Arg-βNA), and azocasein. The third endopeptidase hydrolyzed Bz-L-Arg-βNA, Bz-L-Arg-βNA, and hemoglobin. Fractions of these enzymes extracted from electrophoresis gels were shown to have pH optima from 7.5 to 9.8. AU of the endopeptidases were completely inhibited by diisopropylphosphorofluoridate, demonstrating that they were serine ...


Characterization Of A Fatty Acid Synthetase From Corynebacterium Diphtheriae, Herman W. Knoche, Kirston E. Koths Jan 1973

Characterization Of A Fatty Acid Synthetase From Corynebacterium Diphtheriae, Herman W. Knoche, Kirston E. Koths

Biochemistry -- Faculty Publications

A fatty acid synthetase from Corynebacterium diphtheriae has been purified to a specific activity of 450 nmoles of malonyl coenzyme A incorporated per min per mg. The enzyme is optimally active in 0.5 M phosphate buffer. C. diphtheriae appears to be the most primitive organism having a multienzyme complex for fatty acid synthesis.


Palmityl Coenzyme A Inhibition Of Fatty Acid Synthesis, Herman Knoche, Theodore W. Esders, Kirston Koths, Konrad Bloch Jan 1973

Palmityl Coenzyme A Inhibition Of Fatty Acid Synthesis, Herman Knoche, Theodore W. Esders, Kirston Koths, Konrad Bloch

Biochemistry -- Faculty Publications

The effects of acyl-CoA derivatives (C8 to C20) on the activity

of the fatty acid synthetases from yeast and Corynebacterium

diphtheriae have been examined. Both enzyme

systems are inhibited by the longer chain acyl thioesters

(C16 to C20) and protected against this inhibition by bovine

serum albumin (BSA). Identical relief from acyl-CoA inhibition

is provided by the 6-0-methylglucose-containing

lipopolysaccharide (MGLP), from Mycobacterium phlei. It

is shown that MGLP forms a stable complex with palmitylCoA.

This interaction accounts for the BSA-like effects of

the polysaccharide. BSA and MGLP have two further effects

on the fatty acid synthetases ...


The Structure Of An Ornithine-Containing Lipid From Thiobacillus Thiooxidans, Herman W. Knoche, Jessup M. Shively Jan 1972

The Structure Of An Ornithine-Containing Lipid From Thiobacillus Thiooxidans, Herman W. Knoche, Jessup M. Shively

Biochemistry -- Faculty Publications

The structure of an ornithine-containing lipid from Thio-bacillus thiooxidans

has been elucidated. Methanolysis of

the lipid released methyl cis-ll,lZ-methylene-Z-hydroxyoctadecanoate.

Acid hydrolysis of the residue yielded ornithine

and a mixture of fatty acids, the major components of

which were 3-hydroxyhexadecanoic and 2-hexadecenoic

acids. Identification of the 3-hydroxy fatty acid was based

on the thin layer chromatographic mobilities of the acid, its

methyl ester, the methyl ether, and acetate derivatives of its

methyl ester, on the equivalent chain lengths of the derivatives

of the acid and the acid obtained by oxidation of the

natural acid with permanganate, and on mass spectral ...


The Identification Of Cis-Ii, I2-Methylene-2-Hydroxyoctadecanoic Acid From Thiobacillus Thiooxidans, H. W. Knoche, J. M. Shively Jan 1969

The Identification Of Cis-Ii, I2-Methylene-2-Hydroxyoctadecanoic Acid From Thiobacillus Thiooxidans, H. W. Knoche, J. M. Shively

Biochemistry -- Faculty Publications

A polar fatty acid has been observed as a component of an

ornithine-containing lipid of Thiobacillus thiooxidans. A

comparison of thin layer chromatographic mobilities of reference

compounds to those of the natural acid and its derivatives

suggested that the acid was a 2-hydroxy fatty acid.

The presence of a cyclopropane function in the acid was

indicated by l4e-Iabeling experiments and infrared spectroscopy.

Mass spectrometry of the methyl ester and the acetylated

methyl ester of the natural acid provided a molecular

weight for the acid. Equivalent chain lengths were determined

for the natural acid, the acid obtained by oxidative

decarboxylation of ...


Carbohydrate And Lipid Metabolism During Germination Of Uredospores Of Puccinia Graminis Tritici, J. M. Daly, H. W. Knoche, M. V. Wiese Jan 1967

Carbohydrate And Lipid Metabolism During Germination Of Uredospores Of Puccinia Graminis Tritici, J. M. Daly, H. W. Knoche, M. V. Wiese

Biochemistry -- Faculty Publications

Uredospores of Puccinia gramintis (Pers.) tritici (Eriks. and Henn.) were uniformly labeled with 14C by permitting the host (Triticuml aestivum L.) to carry out photosynthesis in 14CO2 during the process of spore production by the obligate parasite. The use of 14C labeled spores provided advantages in a study of the utilization of endogenous substrates at frequent intervals with small amounts of spores under conditions conducive to germination.


Concerning The Site Of Nitrogen Absorption In Rats Fed Autoclaved Or Raw Soybean Oil Mea, Raymond Borchers Jan 1953

Concerning The Site Of Nitrogen Absorption In Rats Fed Autoclaved Or Raw Soybean Oil Mea, Raymond Borchers

Biochemistry -- Faculty Publications

Carroll, Hensley, and Graham (1) have concluded that much of the nitrogen absorption in rats fed raw soybean oil meal must take place in the cecum. This conclusion was reached from data showing that the apparent digestibility of raw soybean nitrogen in the terminal 20% of the small intestine was 32.65%, whereas in the feces the value was 76.96%. Values reported, for apparent digestibility of heated soybean nitrogen were 78.66% and 81.78%, respectively. This observation presented a notable advance in explaining the lower nutritive value of raw soybeans compared with autoclaved soybeans. It therefore seemed advisable ...


Riboflavin Production By Molds, George L. Peltier, Raymond Borchers Jan 1947

Riboflavin Production By Molds, George L. Peltier, Raymond Borchers

Biochemistry -- Faculty Publications

Very little information is at hand regarding the ability of molds to synthesize riboflavin. Few citations pertaining directly to riboflavin production by true

molds are available. Pontovich (1943) found as much as 2 mg riboflavin per g

of Aspergillus flavus mycelium. Tanner et at. (1945) determined the quantity of

riboflavin in the submerged fermentation media of Penicillium chrysogenum.

The highest value found was 1. 36 mg per ml. The primary purpose of this study

was to screen several hundred isolates, recently obtained from soil, crop residues,

and composts, for their ability to produce riboflavin on a wheat bran substrate.


Tryptophane Metabolism X. The Effect Of Feeding 1(-)-, Dl-, And D(+)-Tryptophane, D(-)And Dl-(Β-3-Indolelactic Acid,(Β-3-Indolepyruvic Acid, And L(-)Kynurenine Upon The Storage Of Liver Glycogen And The Urinary Output Of Kynurenic Acid, Kynurenine, And Total Acetone Bodies, Raymond Borchers, Clarence P. Berg, Newton E. Whitman Jan 1942

Tryptophane Metabolism X. The Effect Of Feeding 1(-)-, Dl-, And D(+)-Tryptophane, D(-)And Dl-(Β-3-Indolelactic Acid,(Β-3-Indolepyruvic Acid, And L(-)Kynurenine Upon The Storage Of Liver Glycogen And The Urinary Output Of Kynurenic Acid, Kynurenine, And Total Acetone Bodies, Raymond Borchers, Clarence P. Berg, Newton E. Whitman

Biochemistry -- Faculty Publications

The amount of tryptophane required for maintenance and growth is small (2). When an excess is supplied to some animals, kynurenic acid is excreted (3) and, under certain conditions, kynurenine also (4). Although these are quantitatively the most important of the known metabolic products of tryptophane, the amounts excreted in extensive tests in the dog and rabbit have usually accounted for less than half, more often for less than a third, of the tryptophane administered (4-6).


Threonine Deficiency In Hydrolysates Of Zein Prepared By Autoclaving, Raymond Borchers, John R. Totter, Clarence P. Berg Jan 1942

Threonine Deficiency In Hydrolysates Of Zein Prepared By Autoclaving, Raymond Borchers, John R. Totter, Clarence P. Berg

Biochemistry -- Faculty Publications

In a previous paper (Borchers and Berg, 1942) we showed that

autoclaving zein with sulfuric acid longer than necessary for complete

hydrolysis causes destruction and racemization; either of

these might account for the failure of such a hydrolysate to

promote growth in young rats when substituted for a hvdrolysate,

prepared by refiuxing, in a diet which produced moderate growth.

It seemed to us that this deterioration in the dietary protein might

well be the result primarily of essential amino acid deficiencies

which could be detected and overcome by appropriate supplementation.

Because threonine is known to be present in zein in ...


The Effect Of Conditions Of Hydrolysis And Of Prolonged Heating Upon The Optical Rotation Of Sulfuric Acid Hydrolysates Of Zein, Raymond Borchers, Clarence P. Berg Jan 1942

The Effect Of Conditions Of Hydrolysis And Of Prolonged Heating Upon The Optical Rotation Of Sulfuric Acid Hydrolysates Of Zein, Raymond Borchers, Clarence P. Berg

Biochemistry -- Faculty Publications

Some time ago we observed that a sulfuric acid hydrolysate of zein prepared in an autoclave at 165˚ did not support growth in young rats when it was supplemented with certain amino acids, even though the same amino acids, added to a hydrolysate prepared by refluxing, permitted moderate growth. Since the optical rotation of the autoclaved hydrolysate was lower than that of the refluxed, either destruction or racemization of essential constituents, or both, might have occurred. Loss of amino nitrogen and production of extra ammonia upon prolonged autoclaving of proteins with acids have been noted by Van Slyke (1912) and ...