scholarly journals The heterogeneity of the lipoprotein lipase of rat epididymal adipose tissue

1978 ◽  
Vol 171 (2) ◽  
pp. 305-311 ◽  
Author(s):  
P Ashby ◽  
A M Tolson ◽  
D S Robinson
Keyword(s):  
Molecular Weight ◽  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Gel Filtration ◽  
Particulate Material ◽  
Epididymal Adipose Tissue ◽  
Fat Cell ◽  
Enzyme Preparations

Lipoprotein lipase is heterogeneous, and it was suggested that the enzyme in adipose tissue is transformed from a species of mol. wt. approx. 120000 to forms of much higher molecular weight as it is secreted from the fat-cell. This paper demonstrates that the forms of higher molecular weight are probably artifacts. Enzyme preparations were characterized by gel filtration, by density-gradient centrifugation and by affinity chromatography. The results indicate that the enzyme forms of mol. wt. greater than 120000 result from an association of the enzyme with particulate material. It is therefore necessary to reconsider schemes that have recently been proposed for the synthesis and export of lipoprotein lipase.

scholarly journals Effect of nutrition on subcellular localization of rat fat-cell lipoprotein lipase

1978 ◽  
Vol 172 (2) ◽  
pp. 239-245 ◽  
Author(s):  
A Vanhove ◽  
C Wolf ◽  
M Breton ◽  
M C Glangeaud
Keyword(s):  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Plasma Membranes ◽  
Total Activity ◽  
Normal Diet ◽  
Epididymal Adipose Tissue ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
Fat Cell ◽  
Intact Tissue

This study supports the possibility for multiple subcellular forms of lipoprotein lipase. 1. The total activity of lipoprotein lipase per g of intact epididymal adipose tissue from fed rats is much higher than that from starved rats. 2. The isolated fat-cells of fed and of starved rats have lipoprotein lipase of almost the same activity per g of fat-pads. The isolated fat-cells of starved rats have a much higher proportion of total activity per g of the intact tissue than do those of fed rats. 3. Under the conditions of homogenization used, only a small proportion of the total activity per g of intact tissue from fed rats was associated with the fat layer which floated to the top of the homogenate during low-speed centrifugation. The different proportions of the specific enzyme activity found in each subcellular fraction are described. 4. Lipoprotein lipase from plasma membranes and microsomal fractions from starved and fed rats was purified by affinity chromatography. 5. The total activity of microsomal lipoprotein lipase per g of intact adipose tissue is enhanced by a normal diet. 6. In intact epididymal adipose tissue from fed rats, the activity per g of tissue of lipoprotein lipase of plasma membranes is much higher than that in the same fraction from starved rats. By contrast, the activities per g of tissue in plasma membranes obtained from starved or from fed rats by collagenase treatment were similar.

scholarly journals THE SUBUNITS IN RABBIT ANTI-FORSSMAN IGM ANTIBODY

1968 ◽  
Vol 127 (5) ◽  
pp. 967-982 ◽  
Author(s):  
Michael M. Frank ◽  
John H. Humphrey
Keyword(s):  
Molecular Weight ◽  
Binding Sites ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sheep Erythrocyte ◽  
Gel Filtration ◽  
Isolation Procedure ◽  
Multiple Binding Sites ◽  
Multiple Binding ◽  
Forssman Antibody

Rabbit IgM anti-Forssman antibody was highly purified and the subunits obtained on reduction and alkylation were labeled radioactively and isolated by two different and unrelated methods. In both cases the subunits were found to have a molecular weight of about 90,000, based on their behavior on density gradient centrifugation and gel filtration, and evidence is given that they contained one light and one heavy chain. The subunits bound only weakly to sheep erythrocyte stroma, and only half could be shown to possess antigen specific sites. The data are consistent with the concept that each anti-Forssman IgM molecule has five effective binding sites, but it is uncertain whether the ineffectiveness of the remaining five H-L chain pairs is inherent in the structure of the IgM molecule or an artifact due to the isolation procedure. Intact IgM anti-Forssman antibody binds very firmly to structures containing multiple repeating antigen sites, and it appears that this is due to the presence of multiple binding sites on the molecule.

Purification et quelques propriétés de l'AMPc phosphodiestérase d'Arthrobacter crystallopoietes

1988 ◽  
Vol 66 (5) ◽  
pp. 454-459 ◽  
Author(s):  
François Schneider ◽  
Gérard Lefebvre ◽  
Michèle Ribolzi-Chery ◽  
Jean-Michel Bertin ◽  
Robert Gay
Keyword(s):  
Molecular Weight ◽  
Active Site ◽  
Cyclic Nucleotides ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Gel Filtration ◽  
Negative Cooperativity ◽  
Divalent Ions ◽  
Camp Phosphodiesterase ◽  
Hydrolysis Of

cAMP phosphodiesterase was purified 8250-fold from extracts of Arthrobacter crystallopoietes, primarily by hydrophobic chromatography. The molecular weight of this enzyme was estimated as 51 000 by gel filtration and density-gradient centrifugation. The results suggest that the enzyme consists of two subunits with a molecular weight of 25 600. Properties of this enzyme are reported, including its negative cooperativity. This phosphodiesterase specifically catalyzes the hydrolysis of 3′,5′-cyclic nucleotides. Divalent ions either have no effect on activity or are weak inhibitors. Photooxidation of the enzyme with methylene blue and treatment with mercuribenzoates suggest that this enzyme may possess an imidazole group within its active site. The effects of thiols and Fe2+ on activity suggests that this enzyme may be a metalloenzyme.

scholarly journals SYNTHESIS OF CHLOROPLAST DNA IN ISOLATED CHLOROPLASTS

1968 ◽  
Vol 38 (1) ◽  
pp. 151-157 ◽  
Author(s):  
N. Steele Scott ◽  
Vinod C. Shah ◽  
Robert M. Smillie
Keyword(s):  
Molecular Weight ◽  
Chloroplast Dna ◽  
Euglena Gracilis ◽  
Bacterial Contamination ◽  
Actinomycin D ◽  
Density Gradient Centrifugation ◽  
Tritiated Thymidine ◽  
Gradient Centrifugation ◽  
Acid Stable ◽  
Isolated Chloroplasts

Chloroplasts isolated from Euglena gracilis incorporated both tritiated thymidine 5'-triphosphate and tritiated deoxyadenosine 5'-triphosphate into an acid-stable fraction. The incorporation was dependent on the presence of all four deoxynucleoside triphosphates and was sensitive to treatment with deoxyribonuclease and actinomycin D. It was demonstrated that bacterial contamination could not account for the incorporation of label. Extraction of DNA from the chloroplasts and subsequent density gradient centrifugation of the DNA in CsCl2 showed that the incorporation was into chloroplast DNA (ρ = 1.686) of high molecular weight.

Adipose tissue in experimental nephrotic syndrome

1963 ◽  
Vol 205 (4) ◽  
pp. 702-706 ◽  
Author(s):  
Alisa Gutman ◽  
Eleazar Shafrir
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Nephrotic Syndrome ◽  
Fatty Acid ◽  
Free Fatty Acids ◽  
Lipoprotein Lipase ◽  
Epididymal Adipose Tissue ◽  
Adequate Nutrition ◽  
Defective Metabolism ◽  
Inadequate Food Intake

Epididymal adipose tissue of aminonucleoside-treated rats, investigated 3 to 6 days after induction of the nephrotic syndrome, had low glycogen levels and showed impaired esterification of free fatty acids and assimilation of lipoprotein triglyceride and markedly reduced liberation of lipoprotein lipase. These results were found to be influenced by the inadequate food intake of the acutely nephrotic animals and comparable to the values of control rats fasted for 2 days. On return to adequate nutrition, which occurred 12–20 days after aminonucleoside treatment, adipose tissue glycogen and free fatty acid assimilation returned toward normal levels but lipoprotein-lipase liberation remained below normal. In rats rendered nephrotic by antikidney serum, the assimilation of free fatty acids and lipoprotein-triglyceride by adipose tissue was impaired in spite of only minor reduction in food consumption. The results indicate that the defective metabolism of adipose tissue in nephrotic animals may be contributory to the nephrotic hypertriglyceridemia.

scholarly journals Factor V activity of platelets: evidence for an activated factor V molecule and for a platelet activator

Blood ◽  
1977 ◽  
Vol 49 (5) ◽  
pp. 819-834 ◽  
Author(s):  
B Osterud ◽  
SI Rapaport ◽  
KK Lavine
Keyword(s):  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Gel Filtration ◽  
Factor V ◽  
Freezing And Thawing ◽  
Early Step ◽  
Platelet Factor ◽  
Plasma Factor ◽  
Native Factor

Abstract This study was prompted by the observation that fresh platelet suspensions--prepared by gel filtration or albumin density gradient centrifugation--possessed only minimal factor V activity, whereas frozen-and-thawed platelet suspensions possessed striking factor V activity. Results of experiments with fresh suspensions suggested that unaltered platelets did not bind plasma factor V. The factor V activity of frozen-and-thawed platelet suspensions was markedly diminished after exposure to a factor V antibody, was not activated by thrombin, and was not associated with an increase in factor V antigen over that found in fresh platelet suspensions. Consequently, disruption by freezing and thawing must have resulted in the appearance of small amounts of an activated factor V molecule in platelet suspensions. Disrupted platelets were shown to activate native factor V, but an interaction between a platelet activator and traces of native factor V in fresh suspensions could not be demonstrated to account for the full activity of frozen-and-thawed suspensions. Apparently, therefore, platelets also contained an activated factor V molecule. Adding collagen, but not adenosine 5′-diphosphate to fresh platelet suspensions increased their factor V activity. Release of an activated platelet factor V molecule after exposure to collagen could represent a physiologically significant early step in hemostasis.

Sign in / Sign up

Export Citation Format

Share Document