scholarly journals Combined endogenous MR biomarkers to assess changes in tumor oxygenation induced by an allosteric effector of hemoglobin

2019 ◽  
Vol 33 (2) ◽  
Author(s):  
Thanh‐Trang Cao‐Pham ◽  
An Tran‐Ly‐Binh ◽  
Arne Heyerick ◽  
Catherine Fillée ◽  
Nicolas Joudiou ◽  
...  
Keyword(s):  
Tumor Oxygenation ◽  
Allosteric Effector

Enhancement of Tumor Oxygenation and Radiation Response by the Allosteric Effector of Hemoglobin, RSR13

2001 ◽  
Vol 156 (3) ◽  
pp. 294-300 ◽  
Author(s):  
George P. Amorino ◽  
Haakil Lee ◽  
George E. Holburn ◽  
Cynthia B. Paschal ◽  
Sherri K. Hercules ◽  
...  
Keyword(s):  
Tumor Oxygenation ◽  
Radiation Response ◽  
Allosteric Effector

Patterns and variability of tumor oxygenation in human soft tissue sarcomas, cervical carcinomas, and lymph node metastases

1995 ◽  
Vol 32 (4) ◽  
pp. 1121-1125 ◽  
Author(s):  
David M. Brizel ◽  
Gary L. Rosner ◽  
Leonard R. Prosnitz ◽  
Mark W. Dewhirst
Keyword(s):  
Lymph Node ◽  
Soft Tissue ◽  
Lymph Node Metastases ◽  
Soft Tissue Sarcomas ◽  
Tumor Oxygenation ◽  
Cervical Carcinomas ◽  
Human Soft Tissue ◽  
Node Metastases

scholarly journals Tumor oxygenation and cancer therapy—then and now

2018 ◽  
pp. 20170955 ◽  
Author(s):  
Veronica S Hughes ◽  
Jennifer M Wiggins ◽  
Dietmar W Siemann
Keyword(s):  
Cancer Therapy ◽  
Tumor Oxygenation

The increase in tumor oxygenation under carbogen breathing induces a decrease in the uptake of [18F]-fluoro-deoxy-glucose

2015 ◽  
Vol 116 (3) ◽  
pp. 400-403 ◽  
Author(s):  
Marie-Aline Neveu ◽  
Vanesa Bol ◽  
Anne Bol ◽  
Caroline Bouzin ◽  
Vincent Grégoire ◽  
...  
Keyword(s):  
Tumor Oxygenation

The interaction of ligands with chemically modified phosphorylase b

1976 ◽  
Vol 54 (5) ◽  
pp. 494-499
Author(s):  
D. Brooks ◽  
S. J. W. Busby ◽  
J. R. Griffiths ◽  
G. K. Radda ◽  
O. Avramovic-Zikic
Keyword(s):  
Conformational Changes ◽  
Spin Label ◽  
Native Enzyme ◽  
Carboxyl Groups ◽  
Chemically Modified ◽  
Allosteric Effector ◽  
Spin Resonance ◽  
Label Probe ◽  
Glycine Ethyl Ester ◽  
Modified Enzyme

Phosphorylase b which had been inactivated with 5-diazo-1H-tetrazole was specifically labelled with 4-iodoacetamidosalicylic acid (a fluorescent probe) or with N-(1-oxyl-2,2,6,6,-tetramethyl-4-piperidinyl)iodoacetamide (a spin label probe) so that the binding of ligands and accompanying conformational changes could be determined by fluorescence or electron spin resonance changes, respectively. The allosteric effector, AMP, causes conformational changes similar to those caused in the native enzyme. The affinity of binding of phosphate or AMP to the inhibited protein is the same as for the unmodified protein. The heterotropic interactions between glucose-1-phosphate or glycogen and AMP are much less in the inactivated enzyme than in unmodified phosphorylase. Using a light scattering assay, it is shown that the modified enzyme binds to glycogen less strongly than the native protein.Phosphorylase b which had been inactivated by carbodiimide in the presence of glycine ethyl ester, resulting in the modification of one or more carboxyl groups, was labelled with the spin label probe described above. The modified enzyme has an affinity for AMP similar to that of the native enzyme. AMP binding to the modified enzyme is tightened by glycogen, weakened by glucose-6-phosphate and is unaffected by glucose- 1-phosphate.The actions of 5-diazo-1H-tetrazole and carbodiimide on phosphorylase are discussed in the light of the above observations.

scholarly journals A conserved C-terminal peptide of sorghum phosphoenolpyruvate carboxylase promotes its proteolysis, which is prevented by Glc-6P or the phosphorylation state of the enzyme

Planta ◽  
2021 ◽  
Vol 254 (3) ◽  
Author(s):  
Jacinto Gandullo ◽  
Rosario Álvarez ◽  
Ana-Belén Feria ◽  
José-Antonio Monreal ◽  
Isabel Díaz ◽  
...  
Keyword(s):  
Amino Acids ◽  
Phosphoenolpyruvate Carboxylase ◽  
Synthetic Peptide ◽  
Phosphorylation State ◽  
Allosteric Effector ◽  
Cathepsin Proteases ◽  
Photosynthesis Pathway

Abstract Main conclusion A synthetic peptide from the C-terminal end of C4-phosphoenolpyruvate carboxylase is implicated in the proteolysis of the enzyme, and Glc-6P or phosphorylation of the enzyme modulate this effect. Abstract Phosphoenolpyruvate carboxylase (PEPC) is a cytosolic, homotetrameric enzyme that performs a variety of functions in plants. Among them, it is primarily responsible for CO2 fixation in the C4 photosynthesis pathway (C4-PEPC). Here we show that proteolysis of C4-PEPC by cathepsin proteases present in a semi-purified PEPC fraction was enhanced by the presence of a synthetic peptide containing the last 19 amino acids from the C-terminal end of the PEPC subunit (pC19). Threonine (Thr)944 and Thr948 in the peptide are important requirements for the pC19 effect. C4-PEPC proteolysis in the presence of pC19 was prevented by the PEPC allosteric effector glucose 6-phosphate (Glc-6P) and by phosphorylation of the enzyme. The role of these elements in the regulation of PEPC proteolysis is discussed in relation to the physiological context.

RSR-13, an allosteric effector of hemoglobin, increases systemic and iliac vascular resistance in rats

1996 ◽  
Vol 271 (2) ◽  
pp. H602-H613 ◽  
Author(s):  
M. P. Kunert ◽  
J. F. Liard ◽  
D. J. Abraham
Keyword(s):  
Cardiac Output ◽  
Vascular Resistance ◽  
Total Peripheral Resistance ◽  
Peripheral Resistance ◽  
Experimental Models ◽  
Metabolic Demand ◽  
Flow Probe ◽  
Inositol Hexaphosphate ◽  
Control Value ◽  
Allosteric Effector

Tissue O2 delivery in excess of metabolic demand may be a factor in the development of high vascular resistance in experimental models of volume-expanded hypertension. This hypothesis was previously tested in rats with an exchange transfusion of red blood cells treated with inositol hexaphosphate or an intravenous infusion of RSR-4, allosteric effectors of hemoglobin. The binding of these drugs with hemoglobin effect a conformational change in the molecule, such that the affinity for O2 is reduced. However, in both preparations, the changes in vascular resistance could have been nonspecific. The present studies used intravenous infusions of RSR-13, which did not share some of the problematic characteristics of RSR-4 and inositol hexaphosphate. Conscious instrumented rats (an electromagnetic flow probe on ascending aorta or an iliac, mesenteric, or renal Doppler flow probe) were studied for 6 h after an RSR-13 infusion of 200 mg/kg in 15 min. This dose significantly increased arterial P50 (PO2 at which hemoglobin is 50% saturated) from 38 +/- 0.8 to 58 +/- 1.4 mmHg at 1 h after the start of the infusion. In the 3rd h cardiac output fell significantly from a control value of 358 +/- 33 to 243 +/- 24 ml.kg-1.min-1 and total peripheral resistance significantly increased from 0.31 +/- 0.03 to 0.43 +/- 0.04 mmHg.ml-1.kg.min. Cardiac output and P50 returned toward control over the next few hours. Neither cardiac output nor total peripheral resistance changed in the group of rats receiving vehicle alone. In a separate group of rats, iliac flow decreased significantly to 60% of control and iliac resistance increased to 160% of control. Iliac flow increased significantly in the group of rats that received vehicle only. Although the mechanism of these changes has not been established, these results suggest that a decreased O2 affinity leads to an increased total peripheral resistance and regional vascular resistance and support the hypothesis that O2 plays a role in the metabolic autoregulation of blood flow.

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