Determination of the rate-limiting step(s) in the biosynthetic pathways leading to penicillin and cephalosporin

1992 ◽  
Vol 10 (3-4) ◽  
pp. 157-163 ◽  
Author(s):  
John J. Usher ◽  
Doris W. Hughes ◽  
Mary Ann Lewis ◽  
Shu-Jen D. Chiang
Keyword(s):  
Biosynthetic Pathways ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

scholarly journals DETERMINATION OF l-HISTIDINE IN NANOGRAM AMOUNTS AND THE QUESTION OF ITS OCCURRENCE IN MAST CELLS

1972 ◽  
Vol 20 (11) ◽  
pp. 917-922 ◽  
Author(s):  
DAVID I. WILKINSON ◽  
DAVID GLICK
Keyword(s):  
Mast Cells ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Peritoneal Mast Cells ◽  
Before And After ◽  
Chromatographic Detection ◽  
Rat Peritoneal Mast Cells ◽  
Rate Limiting

In an attempt to clarify the question of whether histidine is stored in the mast cell for coversion to histamine or whether the rate of conversion is rapid enough to prevent accumulation of histidine so that the rate-limiting step is the histidine uptake, it was found that no histidine was demonstrable in rat peritoneal mast cells by either quantitative analysis or paper chromatographic detection. Microadaptation of Hassall's method, based on conversion of l-histidine by histidase to urocanic acid and measurement of the latter by its absorbance at 277 nm, was made to permit determination of histidine in nanogram amounts in the presence of histamine. This adaptation was found reliable when compared with the o-phthalaldehyde method in estimation of l-histidine in serum and in insulin hydrolysate, and then it was applied to analysis of mast cells before and after l-histidine uptake in vitro. The adaptation should be generally useful in microanalysis of l-histidine in histologically and cytologically defined samples.

Determination of the Isotope Effect of the Enzymatic Oxidation of (R)Carnitine by Displacement of the Equilibrium via Mass Action

1975 ◽  
Vol 30 (7-8) ◽  
pp. 438-441
Author(s):  
Klaus Brendel ◽  
Rubin Bressler ◽  
Miguel A. Alizade
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Isotope Effect ◽  
Mass Action ◽  
Enzymatic Oxidation ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Different Temperatures ◽  
Acid Hydrochloride ◽  
Rate Limiting

Abstract An isotope effect of the dehydrogenation of (R) Carnitine [(R) 3-hydroxy-4-trimethylamino-butyric acid hydrochloride] catalyzed by (R) carnitine dehydrogenase [(R) carnitine: NAD oxido-reductase E.C. 1.1.1.108] from Pseudomonas aeruginosa was measured at different temperatures. It was found that k1H/k3H does not vary greatly with changes of temperature. The value of 3 for k1H/k3H measured at small initial conversions strongly indicated that the rate limiting step of the oxidation of (R) carnitine is the cleavage of the C-H bond at C3.

scholarly journals Mass Transfer Studies on Adsorption of Phenol from Wastewater UsingLantana camara, Forest Waste

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
C. R. Girish ◽  
V. Ramachandra Murty
Keyword(s):  
Mass Transfer ◽  
Lantana Camara ◽  
Model Parameters ◽  
External Mass Transfer ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Forest Waste ◽  
Mass Transfer Studies ◽  
Rate Limiting

Adsorption is one of the important treatment methods for the removal of pollutants from wastewater. The determination of rate controlling step in the process is important in the design of the process. Therefore, in the present work, mass transfer studies were done to evaluate the rate-limiting step in the adsorption of phenol from aqueous solution ontoLantana camara. Different mass transfer models were used to find the rate-limiting step and also to find the values of external mass transfer coefficient and diffusion coefficient. The Biot number was found to investigate the importance of external mass transfer to intraparticle diffusion. From the various models studied and the Biot numbers obtained, it was found that the adsorption onLantana camarawas controlled by film diffusion. The sensitivity analysis was performed to study the significance of the model parameters on the adsorption process.

scholarly journals Mechanism of Up-regulation of Starch Synthesis in Mature Leaves of Transgenic Apple Trees with Decreased Sorbitol Synthesis

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1009D-1009
Author(s):  
Rui Zhou ◽  
Lailiang Cheng ◽  
Abhaya Dandekar
Keyword(s):  
Transgenic Plants ◽  
Starch Synthesis ◽  
Redox Status ◽  
Mature Leaves ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting ◽  
Transgenic Apple ◽  
Hexose Phosphates

The reaction catalyzed by ADP-glucose pyrophosphorylase (AGPase) to form ADP-glucose is a regulatory and rate-limiting step in starch synthesis in plants. In response to decreased sorbitol synthesis, starch synthesis was up-regulated in the transgenic apple plants. In this study, we examined both redox and metabolite regulation of AGPase to understand the mechanism responsible for the up-regulation of starch synthesis. No difference in the monomerization/dimerization of apple leaf AGPase small subunits was observed between the transgenic plants and the untransformed control. NADP-dependent malate dehydrogenase, indicative of chloroplastic redox status, did not show significant change in the transgenic plants either. Determination of key metabolites with nonaqueous fractionation indicated that concentrations of hexose phosphates (mainly glucose-6-phosphate and fructose-6-phosphate) were higher in both the cytosol and chloroplasts of the transgenic plants than in the control, whereas 3-phosphoglycerate (PGA) concentration in the chloroplast was not higher in the transgenic plants. We conclude that accumulation of hexose-phosphates results in a decrease in inorganic phosphate (Pi) concentration and an increase in PGA/Pi ratio in the chloroplast, leading to up-regulation of starch synthesis via activating AGPase.

Determination of the Rate-Limiting Step in Fatty Acid Transport

2019 ◽  
Vol 123 (33) ◽  
pp. 7157-7168 ◽  
Author(s):  
Victoria Cheng ◽  
Dylan R. Kimball ◽  
Dr. John C. Conboy
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Transport ◽  
Acid Transport ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting
Sign in / Sign up

Export Citation Format

Share Document