scholarly journals Stoichiometry of oxygen consumption in the biosynthesis of isopenicillin from a tripeptide

1982 ◽  
Vol 203 (3) ◽  
pp. 791-793 ◽  
Author(s):  
R L White ◽  
E M M John ◽  
J E Baldwin ◽  
E P Abraham
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Electrode ◽  
Stoichiometric Ratio ◽  
O2 Consumption ◽  
Free System ◽  
Cell Free System ◽  
A Cell ◽  
Isopenicillin N

The biosynthesis of isopenicillin N from delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine in a cell-free system has been correlated wih O2 consumption by two methods, involving the use of an oxygen-electrode and an n.m.r. spectrometer respectively. The results are consistent with a 1 : 1 stoichiometric ratio for the dioxygen consumed to the isopenicillin N formed.

scholarly journals DINITROCRESOL AND PHOSPHATE STIMULATION OF THE OXYGEN CONSUMPTION OF A CELL-FREE OXIDATIVE SYSTEM OBTAINED FROM SEA URCHIN EGGS

1949 ◽  
Vol 32 (4) ◽  
pp. 503-509 ◽  
Author(s):  
Robert K. Crane ◽  
Anna K. Keltch
Keyword(s):  
Oxygen Consumption ◽  
Sea Urchin ◽  
Rabbit Kidney ◽  
Free System ◽  
Cell Free System ◽  
Sea Urchin Eggs ◽  
Equivalent Quantity ◽  
A Cell ◽  
Oxidative System ◽  
Stimulation Of

1. A cell-free system capable of using oxygen with oxalacetate as substrate has been prepared from both unfertilized and fertilized sea urchin eggs. The oxygen uptake by this system is about twice that of an equivalent quantity of intact unfertilized eggs and half that of an equivalent quantity of intact fertilized eggs. 2. The oxygen consumption of this cell-free oxidative system can be stimulated by addition of suitable concentrations of 4,6-dinitro-o-cresol or by inorganic phosphate. This confirms, with a cell-free system obtained from sea urchin eggs, the observations of Loomis and Lipmann regarding stimulation of oxygen consumption by a system obtained from rabbit kidney. 3. A preliminary but unsuccessful attempt has been made to determine the conditions under which cell-free, aerobic, phosphorylating systems may be obtained from either unfertilized or fertilized sea urchin eggs.

scholarly journals Conversion of isopenicillin N into penicillin N in cell-free extracts of Cephalosporium acremonium

1981 ◽  
Vol 194 (2) ◽  
pp. 645-647 ◽  
Author(s):  
G S Jayatilake ◽  
J A Huddleston ◽  
E P Abraham
Keyword(s):  
Cephalosporium Acremonium ◽  
Free System ◽  
Cell Free System ◽  
A Cell ◽  
Osmotic Lysis ◽  
Isopenicillin N

In a cell-free system prepared by osmotic lysis of protoplasts of Cephalosporium acremonium, isopenicillin N is converted into penicillin N. The epimerase activity of the system is labile.

Doxorubicin and epirubicin iron-induced generation of free radicals In vitro. A comparative study

1987 ◽  
Vol 7 (8) ◽  
pp. 653-658 ◽  
Author(s):  
Kjell Grankvist ◽  
Roger Henriksson
Keyword(s):  
Oxygen Consumption ◽  
Free Radicals ◽  
Myocardial Injury ◽  
Oxygen Free Radicals ◽  
Oxygen Electrode ◽  
Inhibitory Effect ◽  
Free System ◽  
A Cell ◽  
Strong Inhibitory Effect

To ascertain any differences in myocardial injury exerted by the anthracyclines doxorubicin and epirubicin, their ability to generate oxygen free radicals when mixed with Fe(II) was examined in vitro using an oxygen electrode. 5–250 μg/ml doxorubicin or epirubicin consumed oxygen when mixed with 50 or 100 μmol/1 Fe(II). Addition of 75 μmol/1 cytochrome C showed that of the consumed oxygen, approximately 80% entered the monovalent pathway of oxygen reduction. The strong inhibitory effect of 250 mg/1 catalase indicates that most of the superoxide radicals generated are further reduced to hydrogen peroxide by both anthracyclines. Addition of metal chelators DTPA (100/μmol/1), or DDTC (50 μmol/1) did not affect oxygen consumption, whereas EDTA (100/μmol/1) or desferrioxamine (100 μmol/1) with anthracyclines and Fe(II) rather stimulated oxygen consumption. It is concluded that there are no significant differences in the amount or proportion of generated oxygen free radicals between doxorubicin and epirubicin when mixed with Fe(II) in a cell-free system in vitro. Thus, the ability of the anthracyclines, in conjunction with iron alone, to generate radicals does not explain the differences of the drugs in causing myocardial injury.

scholarly journals Cell-free conversion of isopenicillin N into deacetoxycephalosporin C by Cephalosporium acremonium mutant M-0198

1981 ◽  
Vol 194 (2) ◽  
pp. 649-651 ◽  
Author(s):  
J E Baldwin ◽  
J W Keeping ◽  
P D Singh ◽  
C A Vallejo
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Cephalosporium Acremonium ◽  
Resistant Material ◽  
Free System ◽  
Cell Free System ◽  
Chromatography Analysis ◽  
A Cell ◽  
Isopenicillin N

In a cell-free system prepared by lysis of protoplasts of Cephalosporium acremonium mutant M-0198, isopenicillin N was converted into a penicillinase-resistant material that behaved like deacetoxycephalosporin C on high-pressure liquid chromatography analysis. This activity was found to be unstable to storage at -80 degrees C; 70-80% of the activity was lost after 1 day.

scholarly journals Effect of detergents on sterol synthesis in a cell-free system of yeast

1982 ◽  
Vol 23 (6) ◽  
pp. 803-810
Author(s):  
S Hata ◽  
T Nishino ◽  
N Ariga ◽  
H Katsuki
Keyword(s):  
Sterol Synthesis ◽  
Free System ◽  
Cell Free System ◽  
A Cell

scholarly journals Reconstitution of Endosomal Proteolysis in a Cell-free System

1989 ◽  
Vol 264 (10) ◽  
pp. 5392-5399
Author(s):  
L S Mayorga ◽  
R Diaz ◽  
P D Stahl
Keyword(s):  
Free System ◽  
Cell Free System ◽  
A Cell
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