The catechol oxidase of bean leaves (Phaseolus vulgaris)

1970 ◽  
Vol 48 (6) ◽  
pp. 1029-1032 ◽  
Author(s):  
David Racusen
Keyword(s):  
Phaseolus Vulgaris ◽  
Density Gradient ◽  
Colorimetric Assay ◽  
Sucrose Density Gradient ◽  
Leaf Expansion ◽  
Assay System ◽  
Catechol Oxidase ◽  
Gradient Electrophoresis ◽  
Bean Leaves

Bean leaf catechol oxidase was studied with a new colorimetric assay system. The enzyme, though specific for o-diphenols, had a relatively low affinity for catechol. Borate, which complexes with catechol, inhibited the enzyme. Results obtained with DEAE chromatography and sucrose density gradient electrophoresis indicated that the enzyme consisted of a group of isozymes whose assay was independent of contaminating peroxidase. Both catechol oxidase and peroxidase increased during leaf expansion.

Density-gradient electrophoresis of native and of rennet-treated casein micelles

1971 ◽  
Vol 38 (2) ◽  
pp. 151-164 ◽  
Author(s):  
Margaret L. Green ◽  
G. Crutchfield
Keyword(s):  
Electric Field ◽  
Density Gradient ◽  
Ionic Composition ◽  
Sucrose Density Gradient ◽  
Casein Micelles ◽  
Gradient Electrophoresis

SummaryAnalytical electrophoresis of native and of rennet-treated casein micelles was carried out at 26 and at 5°C in a sucrose density gradient in a medium of the same ionic composition as milk. Under normal circumstances, the micelles were negatively charged and showed little heterogeneity in the electric field, the fastestmoving ones having at 26°C a mobility not more than 30% greater than that of the slowest. Native micelles were more highly charged at 5 than at 26°C; at each temperature, the mobility was approximately halved by rennet treatment. The results suggest that the effects of rennet treatment and of alterations in temperature on the tendency of the micelles to clot can be entirely explained as being caused by changes in charge.

scholarly journals Organization of the phosphoinositide cycle. Assessment of inositol transferase activity in purified plasma membranes

1993 ◽  
Vol 290 (1) ◽  
pp. 179-183 ◽  
Author(s):  
O M Santiago ◽  
L I Rosenberg ◽  
M E Monaco
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Density Gradient ◽  
Plasma Membranes ◽  
Sucrose Density Gradient ◽  
Tumour Cells ◽  
Assay System ◽  
Mammary Tumour ◽  
Transferase Activity ◽  
Phosphoinositide Cycle

Experiments were carried out to determine whether or not CDP-diacylglycerol:myo-inositol 3-phosphatidyltransferase (IT) activity (EC 2.7.8.11) could be detected in purified plasma-membrane fractions from WRK-1 rat mammary tumour cells. These cells have previously been shown to have a very active phosphoinositide cycle. Sucrose-density-gradient-purified plasma membranes contained no IT activity that could not be accounted for by endoplasmic-reticulum contamination. However, we also determined that the relative amount of IT activity in endoplasmic reticulum and plasma-membrane fractions could be altered by changing the concentration of detergent in the assay system.

The Combining Ability of Glycoproteins IIb, IIIa and Ca2+ in EDTA-Treated Nonaggregable Platelets

1983 ◽  
Vol 50 (04) ◽  
pp. 848-851 ◽  
Author(s):  
Marjorie B Zucker ◽  
David Varon ◽  
Nicholas C Masiello ◽  
Simon Karpatkin
Keyword(s):  
Density Gradient ◽  
Combining Ability ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Electrophoretic Pattern ◽  
Sucrose Density Gradient ◽  
Irreversible Loss ◽  
Sucrose Density Gradient Centrifugation ◽  
Crossed Immunoelectrophoresis ◽  
Triton X

SummaryPlatelets deprived of calcium and incubated at 37° C for 10 min lose their ability to bind fibrinogen or aggregate with ADP when adequate concentrations of calcium are restored. Since the calcium complex of glycoproteins (GP) IIb and IIIa is the presumed receptor for fibrinogen, it seemed appropriate to examine the behavior of these glycoproteins in incubated non-aggregable platelets. No differences were noted in the electrophoretic pattern of nonaggregable EDTA-treated and aggregable control CaEDTA-treated platelets when SDS gels of Triton X- 114 fractions were stained with silver. GP IIb and IIIa were extracted from either nonaggregable EDTA-treated platelets or aggregable control platelets with calcium-Tris-Triton buffer and subjected to sucrose density gradient centrifugation or crossed immunoelectrophoresis. With both types of platelets, these glycoproteins formed a complex in the presence of calcium. If the glycoproteins were extracted with EDTA-Tris-Triton buffer, or if Triton-solubilized platelet membranes were incubated with EGTA at 37° C for 30 min, GP IIb and IIIa were unable to form a complex in the presence of calcium. We conclude that inability of extracted GP IIb and IIIa to combine in the presence of calcium is not responsible for the irreversible loss of aggregability that occurs when whole platelets are incubated with EDTA at 37° C.

Characterization and Partial Purification of Heterodisperse Polysomal RNAs in Normal and Neoplastic Cells

1972 ◽  
Vol 58 (2) ◽  
pp. 71-94
Author(s):  
Ada Sacchi ◽  
Gianni Chinali ◽  
Susetta Pons ◽  
Michela Galdieri ◽  
Piero Cammarano
Keyword(s):  
Size Distribution ◽  
Density Gradient ◽  
Rat Liver ◽  
Sucrose Density Gradient ◽  
Partial Purification ◽  
Messenger Rnas ◽  
Alkaline Ph ◽  
Sedimentation Profile ◽  
Molecular Weights ◽  
Phenol Extraction

The size distribution of cytoplasmic messenger RNAs (m-RNA) has been studied in rat liver and in monodifferentiated cells (mouse reticulocytes and myelomas). It has been found that the RNA which exhibits a « rapid turnover » and a polydisperse profile of radioactivity is refractory to phenol extraction. This property has been exploited to selectively isolate m–RNA from the phenol residue by means of an extraction at an alkaline pH. The sucrose density gradient profiles of m–RNA isolated from monodifferentiated cells show monodisperse peaks having the sedimentation coefficients expected on the basis of the molecular weights of monocistronic messages for α and β chains of hemoglobin (reticulocytes) and L and H chains of immunoglobulin (myelomas). The sedimentation profile of cytoplasmic m–RNA associated with rat liver polysomes shows a much broader distribution, with sedimentation coefficients ranging from 8 S to 28 S.

scholarly journals Ribonucleic Acid Biosynthesis in Human Leukocytes

Blood ◽  
1966 ◽  
Vol 28 (2) ◽  
pp. 188-200 ◽  
Author(s):  
MARTIN J. CLINE
Keyword(s):  
Density Gradient ◽  
Ribonucleic Acid ◽  
Turnover Rate ◽  
Rna Synthesis ◽  
Gradient Analysis ◽  
Sucrose Density Gradient ◽  
Acid Biosynthesis ◽  
Total Load ◽  
Human Leukocytes ◽  
Particle Ingestion

Abstract Phagocytosis has profound effects on several aspects of the RNA metabolism of human leukocytes. The major changes induced by particle ingestion appear to be (1) an increased uptake of pyrimidine precursors from the suspending medium, (2) a contraction in the size of the nucleotide pool, (3) an accelerated rate of destruction of preexisting RNA, and (4) an increased rate of RNA synthesis. Sucrose density gradient analysis of the newly synthesized RNA suggests that several classes of RNA are involved in this process. The increased turnover rate of the nucleotide pool and of the cellular RNA of the leukocyte is proportional, within limits, to the total load of ingested particles.

ANALYSIS OF RIBOSOMES AND POLYSOMES DERIVED FROM RABBIT MAMMARY GLANDS DURING PREGNANCY AND LACTATION

1971 ◽  
Vol 49 (4) ◽  
pp. 667-NP ◽  
Author(s):  
I. D. HERRIMAN ◽  
G. D. BAIRD ◽  
JUDY M. BRUCE
Keyword(s):  
Electron Microscopy ◽  
Density Gradient ◽  
Gradient Analysis ◽  
Late Pregnancy ◽  
Sucrose Density Gradient ◽  
Mammary Glands ◽  
Pregnancy And Lactation

SUMMARY Whole-ribosome and polysome-enriched fractions were prepared from the mammary glands of rabbits during late pregnancy and lactation. The composition of the fractions was determined by sucrose density gradient analysis and electron microscopy. The range of size of polysomal aggregates was similar in the late-pregnant and lactating gland, with aggregates containing five to nine ribosomal units predominating. However, the amount of polysomes relative to monosomes was invariably found to increase after parturition. The greater portion of this increase was accounted for by the increased abundance of aggregates containing five to nine units.

A colorimetric assay system for dopamine using microfluidic paper-based analytical devices

Talanta ◽  
2019 ◽  
Vol 194 ◽  
pp. 171-176 ◽  
Author(s):  
Chunye Liu ◽  
Frank A. Gomez ◽  
Yanqing Miao ◽  
Ping Cui ◽  
Wilson Lee
Keyword(s):  
Colorimetric Assay ◽  
Assay System
Sign in / Sign up

Export Citation Format

Share Document