scholarly journals The separation and distribution of simple and condensed leucoanthocyanins of the tea plant (Camellia sinensis L.)

1969 ◽  
Vol 113 (5) ◽  
pp. 757-763 ◽  
Author(s):  
G. I. Forrest ◽  
D S Bendall
Keyword(s):  
Molecular Weight ◽  
Gel Filtration ◽  
Inverse Correlation ◽  
Tea Plant ◽  
Degree Of Polymerization ◽  
Monomer Ratio ◽  
Lower Mobility ◽  
High Concentrations ◽  
Root Tissues ◽  
Very High

1. Leucoanthocyanin monomers of high mobilities in aqueous solvents on thinlayer chromatograms, assumed to be structurally simple, were characteristic of mature bulky tissues, whereas members of lower mobility were confined to young vegetative and floral tissues. 2. Flavylogens were separated by gel filtration on Sephadex columns into monomeric, oligomeric and polymeric fractions. 3. The polymeric fraction from young brown stems was heterogeneous, one-half having a molecular weight of about 3400, one-third a molecular weight between 3600 and 17000, and the remainder a molecular weight of over 17000. 4. Leaves had low flavylogen concentrations; only monomers were present. Stem tissues were rich in polymers, which increased with the age of the young stem and decreased inwards through the wood. The maximal flavylogen concentrations were in the phloem and cambium from mature stems, where all three fractions were richly present. The periderm tissue and, to a lesser extent, the seed coat were characterized by a very high polymer/monomer ratio, exhibiting a much higher degree of polymerization than the wood. Root tissues contained high concentrations of monomers. 5. In general, there was an inverse correlation between the extent of polymerization and the complexity of the monomers present. 6. The results are in favour of the thesis that the function of the flavanols is, after polymerization to condensed tannins, to impregnate dead structural tissues and thereby to protect them from infection and decay.

Tissue-type plasminogen activator release in response to epinephrine in perfused rat hindlegs

1989 ◽  
Vol 256 (2) ◽  
pp. H404-H410
Author(s):  
G. J. Zhu ◽  
M. Abbadini ◽  
M. B. Donati ◽  
L. Mussoni
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Perfusion Pressure ◽  
Maximum Level ◽  
Tissue Type ◽  
Tissue Type Plasminogen Activator ◽  
Type Plasminogen Activator ◽  
Beta Receptors ◽  
High Concentrations ◽  
Very High

We have studied the mechanism of release of plasminogen activator (PA) activity induced by epinephrine in the perfused rat hindleg model. Epinephrine perfusion at the dose of 12.5 microM caused a slighter effect on PA activity but an immediate increase in the perfusion pressure. At 25 microM, epinephrine induced a marked increase in PA activity that reached the maximum level at the end of the drug perfusion. The same response was induced by repeated stimulations with epinephrine (25 microM) only if the second stimulus was given 20-25 min apart from the first one. PA release could be blocked by propranolol (300 microM), a nonspecific beta-blocker, and not by phentolamine, a nonspecific alpha-blocker, unless used at very high concentrations (1,250 microM). Perfusion with dibutyryl adenosine 3',5'-cyclic monophosphate (DbcAMP) alone induces an immediate and transient increase in PA activity, but no potentiation could be demonstrated if theophylline was perfused together with epinephrine. The released PA has been characterized on the basis of molecular weight and immunological criteria as t-PA- and u-PA-like molecules in basal conditions. Epinephrine perfusion induced an increase only in the t-PA-like protein. These data indicate that the release of t-PA-like activity observed after epinephrine perfusion is mainly mediated by beta-receptors and is independent from its vasoactive action.

Subunit Structure and some Properties of Pyruvate Kinase of Neurospora

1975 ◽  
Vol 53 (2) ◽  
pp. 109-119 ◽  
Author(s):  
M. Kapoor
Keyword(s):  
Molecular Weight ◽  
Pyruvate Kinase ◽  
Guanidine Hydrochloride ◽  
Gel Filtration ◽  
Sedimentation Equilibrium ◽  
Phosphoryl Group ◽  
Subunit Structure ◽  
Equilibrium Studies ◽  
Variable Extent ◽  
High Concentrations

Pyruvate kinase isolated from Neurospora and purified to homogeneity has been shown to be a tetramer of molecular weight around 242 000 by gel filtration studies and 239 000 daltons by sedimentation equilibrium measurements. The monomer produced by treatment with guanidine hydrochloride is found to be 51 000–52 000 daltons by sedimentation equilibrium studies; a molecular weight of 62 000 was determined for the monomer generated by SDS treatment by electrophoresis in SDS–polyacrylamide gels. The enzyme has an isoelectric point of 6.35–6.41. Substrate saturation kinetics of PEP show a variable extent of cooperativity depending upon the buffer ions employed in the assay. ADP is the most effective phosphoryl group acceptor, GDP and IDP being poor substitutes. A divalent cation, Mg2+, is required for activity. At low concentrations, Ca2+ acts as an activator of pyruvate kinase but it is inhibitory at high concentrations. Fructose 1,6-diphosphate is the most potent allosteric activator, fructose 6-phosphate being next in order of effectiveness. Valine is a powerful inhibitor. Phenylalanine, tyrosine, and tryptophan are without any effect individually, but their simultaneous presence results in a considerable activation. Alanine does not affect this enzyme appreciably.

scholarly journals Accumulation of malto-oligosaccharides in the syncytiotrophoblastic cells of first-trimester human placentas

1981 ◽  
Vol 200 (1) ◽  
pp. 93-98 ◽  
Author(s):  
S J Fisher ◽  
R A Laine
Keyword(s):  
Gel Filtration ◽  
First Trimester ◽  
Structural Elements ◽  
Trophoblastic Cells ◽  
Highly Active ◽  
A Cell ◽  
Liver Homogenates ◽  
High Concentrations ◽  
Very High

A cell-surface microvillar fraction that was isolated from the syncytiotrophoblastic cells of first-trimester human placentas was found to contain very high concentrations (890 +/- 32 microgram of hexose/mg of protein) of a class of low-molecular-weight oligosaccharides that were comprised entirely of glucose. T.l.c. and gel filtration showed that the saccharides contained from one to six glucose residues. The structures of the most prominent members of the series, a tetra- and a tri-saccharide, were determined. The anomeric configuration of the glucose residues was alpha, and methylation linkage analysis gave terminal and 4-linked hexose residues. These malto-oligosaccharides contained one reducing terminus per molecule, indicating that they were free and not bound to other structural elements of the cells. Within the placenta they appeared to be concentrated in the first-trimester trophoblastic cells, since crude membrane and particulate fractions isolated from either term trophoblastic cells or cultured placental fibroblasts did not contain detectable amounts of glucose oligomers. This series of oligosaccharides was similar to the products that are formed when glycogen is degraded by alpha-amylase in liver homogenates and may be indicative of a similar, highly active enzymic reaction closely associated with the brush border of the syncytiotrophoblastic cells of the first-trimester human placenta. Although the role of these oligosaccharides remains obscure they are probably involved in foetal metabolism.

Rapid release of peroxidase by peanut cells in suspension culture

1973 ◽  
Vol 51 (6) ◽  
pp. 1169-1175 ◽  
Author(s):  
R. B. van Huystee ◽  
G. Turcon
Keyword(s):  
Molecular Weight ◽  
Metabolic Rate ◽  
Suspension Culture ◽  
Gel Filtration ◽  
Electron Microscopic ◽  
Rapid Release ◽  
Microscopic Studies ◽  
Very High

Peanut cells in a suspension culture were studied with regard to the process of peroxidase release and some ultrastructural features that appeared to relate to this process. By means of gel filtration on Sephadex G-200 it was established that protein released into the medium had the same molecular weight as the peroxidase found in this medium. From information gained through the electron-microscopic studies and from incorporation of labeled leucine, it may be deduced that the metabolic rate of these cells is very high. Within 2 h after incubation with radioactive leucine it was noted that newly synthesized protein was released by the cells into the medium. This protein had also the same characteristics of peroxidase and its synthesis and subsequent appearance in the medium could be reduced by incubation in the presence of cycloheximide. A possible explanation for the presence of these large quantities of peroxidase is discussed.

scholarly journals The cellulolytic enzymes of Botryodiplodia theobromae Pat. Separation and characterization of cellulases and β-glucosidases

1979 ◽  
Vol 177 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Gabriel M. Umezurike
Keyword(s):  
Molecular Weight ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
Exchange Chromatography ◽  
Cellulolytic Enzymes ◽  
Botryodiplodia Theobromae ◽  
Molecular Weights ◽  
Low Concentrations ◽  
High Concentrations

1. Filtrates from cultures of different ages of Botryodiplodia theobromae Pat. were fractionated by gel filtration, ion-exchange chromatography and polyacrylamide-gel electrophoresis. 2. Five cellulases (C1, C2, C3, C4 and C5) were found, and their molecular weights, estimated by gel filtration, were 46000–48000 (C1), 30000–35000 (C2), 15000–18000 (C3), 10000–11000 (C4) and 4800–5500 (C5). 3. Cellulase C5 was absent from old culture filtrates. 4. Cellulase C1 had little or no activity on CM-cellulose (viscometric assay), but degraded cotton flock and Whatman cellulose powder to give cellobiose only. 5. The other components (C2–C5) produced cellobiose and smaller amounts of glucose and cellotriose from cellulosic substrates and were more active in lowering the viscosity of CM-cellulose. 6. The ratio of activities assayed by viscometry and by the release of reducing sugars from CM-cellulose increased with decrease in the molecular weights of cellulases C2–C5. 7. Cellobiose inhibited the activities of the cellulases, but glucose stimulated at low concentrations although it inhibited at high concentrations. 8. A high-molecular-weight β-glucosidase (component B1, mol.wt. 350000–380000) predominated in filtrates from young cultures, but a low-molecular-weight enzyme (B4, mol.wt. 45000–47000) predominated in older filtrates. 9. Intermediate molecular species of β-glucosidase (B2, mol.wt. 170000–180000; B3, mol.wt. 83000–87000) were also found. 10. Cellulases C2–C5 acted in synergism with C1, particularly in the presence of β-glucosidase.

scholarly journals The biosynthesis of glucagon in perfused rat pancreas

1973 ◽  
Vol 134 (2) ◽  
pp. 473-480 ◽  
Author(s):  
Kevin J. O'Connor ◽  
Adrian Gay ◽  
Norman R. Lazarus
Keyword(s):  
Molecular Weight ◽  
Specific Binding ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
Leucine Incorporation ◽  
Perfused Rat Pancreas ◽  
Rat Pancreas ◽  
Extractable Protein ◽  
High Concentrations ◽  
Glucagon Immunoreactivity

The biosynthesis of glucagon was studied by using the recirculated, isolated perfused rat pancreas. [3H]Tryptophan was initially incorporated into acid–ethanol-extractable protein, which on gel filtration was eluted with a molecular weight of about 9000 and contained a small amount of glucagon immunoreactivity. With longer incubation [3H]tryptophan incorporation into a second peak was obtained in an identical position with that of the majority of rat glucagon immunoreactivity. This peak of labelled protein exhibited migration characteristics on polyacrylamide-gel electrophoresis identical with those of rat glucagon and was identified as newly synthesized glucagon by demonstration of specific binding and dissociation behaviour with glucagon antibodies. The incorporation of [3H]tryptophan into acid–ethanol-extractable protein was inhibited by cycloheximide. High concentrations of glucose increased [3H]tryptophan incorporation into high-molecular-weight protein but decreased incorporation into proteins smaller than cytochrome c. The pattern of [3H]leucine incorporation into protein was similar to that of [3H]tryptophan.

Insights on Monoclonal Antibodies to Kininogens' Heavy Chain Which Influence Kininogens' Binding to Platelets

1992 ◽  
Vol 68 (02) ◽  
pp. 143-148 ◽  
Author(s):  
Yongping Jiang ◽  
Weerasak Nawarawong ◽  
Frank J Meloni ◽  
Alvin H Schmaier
Keyword(s):  
Molecular Weight ◽  
Monoclonal Antibodies ◽  
Affinity Chromatography ◽  
Immunosorbent Assay ◽  
Heavy Chain ◽  
Gel Filtration ◽  
Enzyme Linked Immunosorbent Assay ◽  
Low Molecular Weight ◽  
High Concentrations ◽  
Sepharose 4B

SummaryPurified domains of low molecular weight kininogen (LK) can be used directly to determine the epitopes of monoclonal antibodies (mAbs) that have been shown to influence kininogen function. LK, purified from plasma by carboxymethyl-papain-Sepharose 4B affinity chromatography and kaolin adsorption, was digested by trypsin and chymotrypsin. The domains of LK were then separated by gel filtration followed by carboxymethyl-papain-Sepharose 4B affinity chromatography. Using the purified domains of LK’s heavy chain, the regions on kininogens' heavy chain which various monoclonal antibodies are directed to were determined by enzyme-linked immunosorbent assay and immunoblotting. MAb 2B5 which neutralized kininogens' ability to inhibit calpain cross-reacted with domains 2 and 3. MAb HKH8 which reacted with kininogens' domain 1 and 2 was found to inhibit 125I-HK binding to platelets. At two-fold molar excess, mAb HKH8 was a better inhibitor of 125I-HK binding to platelets than higher concentrations, where the antibody was shown to cause increased binding to platelets. Alternatively, HKH8 F(ab')2 completely inhibited 125I-HK binding to platelets even at high concentrations of antibody. These studies indicate that purified domains of kininogens' heavy chain can be used to rapidly localize epitopes for antibodies. Further, mAb HKH8 should be a valuable probe to understand the mechanisms of kininogens' binding to platelets.

Big ANF: large-molecular-weight ANF in plasma. I. Gel filtration and affinity chromatography studies

1991 ◽  
Vol 261 (4) ◽  
pp. E516-E524
Author(s):  
N. Wilson ◽  
V. Yakoleff ◽  
R. Keeler
Keyword(s):  
Molecular Weight ◽  
Affinity Chromatography ◽  
Gel Electrophoresis ◽  
Atrial Natriuretic Factor ◽  
Molecular Form ◽  
Gel Filtration ◽  
Gel Chromatography ◽  
Natriuretic Factor ◽  
Large Molecular Weight ◽  
High Concentrations

A large molecular form of immunoreactive atrial natriuretic factor (irANF) was demonstrated in plasma of rabbit and rat on the basis of gel filtration experiments. This big ANF was not retained by octadecylsilane cartridges and cross-reacted with four anti-ANF antisera of different specificities. Gel filtration in acid, but not in 8 M urea, resulted in material with elution characteristics of irANF. Affinity chromatography and gel electrophoresis of big ANF suggested that the material was similar to albumin. However, high concentrations of big ANF were found in analbuminemic rats, with characteristics similar to those seen in rabbit and normal rats (affinity and gel chromatography and gel electrophoresis). We thus conclude that big ANF represents a bound form of ANF in circulation and that the carrier is similar to but not identical with albumin.

Excretion of nitrogen assimilated from N2 fixed by nodulated roots of alfalfa (Medicago sativa)

1986 ◽  
Vol 64 (9) ◽  
pp. 2063-2067 ◽  
Author(s):  
T. C. Ta ◽  
F. D. H. Macdowall ◽  
M. A. Faris
Keyword(s):  
Plant Tissues ◽  
Culture Solution ◽  
Fixed Nitrogen ◽  
Nitrogenous Compounds ◽  
Solution Bathing ◽  
High Concentrations ◽  
Hydroponically Grown ◽  
Root Tissues ◽  
N Compounds ◽  
Very High

Root excretions into the medium of hydroponically grown N2-fixing alfalfa were studied by quantitative and qualitative measurement of nitrogenous compounds in frequently collected aliquots of the culture solutions. Considerable amounts of several nitrogenous compounds were excreted from the nodulated roots. Ammonia, glutamate, serine, alanine, and aspartate were the main compounds excreted and were similar in proportion to the soluble nitrogenous compounds in nodule and root tissues, with the exception of asparagine. Asparagine was present in very high concentrations in the plant tissues and also in the root xylem exudates destined for the shoots, but it was not detected in the solution bathing the roots. 15N2 was also supplied to the nodulated roots of alfalfa and the flow of the label was followed both in the plant tissues and in the culture solution. Results showed that the amounts of nitrogenous compounds excreted to the medium were related to their formation following N2 fixation and also indicated that the recently fixed nitrogen was the main source of the excreted N compounds.

scholarly journals Size heterogeneity of rat pituitary prolactin

1980 ◽  
Vol 189 (3) ◽  
pp. 605-614 ◽  
Author(s):  
M Wallis ◽  
M Daniels ◽  
S A Ellis
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Paper Electrophoresis ◽  
Freezing And Thawing ◽  
Molecular Weights ◽  
Size Heterogeneity ◽  
Very High

The occurrence of multiple forms of rat prolactin with different molecular weights (size heterogeneity) was studied with anterior pituitary extracts, purified rat prolactin and 125I-labelled rat prolactin. In each case, three main forms of the hormone were detected by gel filtration on Sephadex G-100: a major one (80–90%) corresponding to monomeric prolactin (mol.wt. 22000–25000), a peak (8–20%) that could be a dimer (mol.wt. 45000–50000) and a small quantity (1–5%) of a component of much greater molecular weight. On freezing and thawing of 125I-labelled rat prolactin, there was little interconversion of monomer and ‘dimer’ peaks, but both were converted substantially to very high-molecular-weight material. All three peaks of 125I-labelled rat prolactin could be precipitated by anti-(rat prolactin) serum and all three gave similar patterns of radioactive peptides after digestion with chymotrypsin followed by high-voltage paper electrophoresis. On sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, the monomer peak of 125I-labelled prolactin migrated as a single component of mol.wt. 22000, the very high-molecular-weight peak largely dissociated to a component running in the same position as the monomer, and the ‘dimer’ peak migrated partly as a component of mol.wt. 45000 and partly as a component migrating with monomeric prolactin. No treatment was found that could dissociate the ‘dimer’ peak completely to monomeric prolactin.

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