Measuring anion transport selectivity: a cautionary tale

2021 ◽  
Author(s):  
Xin Wu ◽  
Philip A. Gale
Keyword(s):  
Anion Transport ◽  
Cautionary Tale ◽  
Anion Selectivity ◽  
Ph Dependent

pH-dependent liposomal assays are often used to determine anion selectivity in transmembrane anion transport experiments. In this communication, we discuss the validity and limitations of these assays, and provide guidelines for their use to avoid misleading results.

scholarly journals F−/Cl− selectivity in CLCF-type F−/H+ antiporters

2014 ◽  
Vol 144 (2) ◽  
pp. 129-136 ◽  
Author(s):  
Ashley E. Brammer ◽  
Randy B. Stockbridge ◽  
Christopher Miller
Keyword(s):  
Low Voltage ◽  
Bacterial Species ◽  
Sequence Divergence ◽  
Anion Transport ◽  
Ion Binding ◽  
Sequence Comparisons ◽  
Anion Transporters ◽  
Anion Selectivity ◽  
Equilibrium Binding ◽  
Binding Center

Many bacterial species protect themselves against environmental F− toxicity by exporting this anion from the cytoplasm via CLCF F−/H+ antiporters, a subclass of CLC superfamily anion transporters. Strong F− over Cl− selectivity is biologically essential for these membrane proteins because Cl− is orders of magnitude more abundant in the biosphere than F−. Sequence comparisons reveal differences between CLCFs and canonical Cl−-transporting CLCs within regions that, in the canonical CLCs, coordinate Cl− ion and govern anion transport. A phylogenetic split within the CLCF clade, manifested in sequence divergence in the vicinity of this ion-binding center, raises the possibility that these two CLCF subclades might exhibit differences in anion selectivity. Several CLCF homologues from each subclade were examined for F−/Cl− selectivity of anion transport and equilibrium binding. Differences in both of these anion-selectivity metrics correlate with sequence divergence among CLCFs. Chimeric constructs identify two residues in this region that largely account for the subclade differences in selectivity. In addition, these experiments serendipitously uncovered an unusually steep, Cl−-specific voltage dependence of transport that greatly enhances F− selectivity at low voltage.

scholarly journals Transmembrane anion transport mediated by halogen bonding and hydrogen bonding triazole anionophores

2020 ◽  
Vol 11 (18) ◽  
pp. 4722-4729 ◽  
Author(s):  
Laura E. Bickerton ◽  
Alistair J. Sterling ◽  
Paul D. Beer ◽  
Fernanda Duarte ◽  
Matthew J. Langton
Keyword(s):  
Hydrogen Bonding ◽  
Lipid Bilayer ◽  
Halogen Bonding ◽  
Anion Transport ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Triazole Derivatives ◽  
Anion Selectivity

Halogen and hydrogen bonding 1,2,3-triazole derivatives efficiently mediate anion transport across lipid bilayer membranes with unusual anion selectivity profiles.

Police Work Addiction: A Cautionary Tale.

2003 ◽  
Author(s):  
Gerard J. Solan ◽  
Jean M. Casey
Keyword(s):  
Police Work ◽  
Cautionary Tale ◽  
Work Addiction

The Reaction of Thiol Compounds with the Vitamin-K Dependent Clotting Factors

1969 ◽  
Vol 21 (03) ◽  
pp. 573-579 ◽  
Author(s):  
P Fantl
Keyword(s):  
Prothrombin Time ◽  
Vitamin K ◽  
Anaerobic Conditions ◽  
Clotting Factors ◽  
Thiol Compounds ◽  
Aerobic Conditions ◽  
One Stage ◽  
Factor Ii ◽  
Ph Dependent ◽  
The One

SummaryTreatment of human and dog oxalated plasma with 0.2 to 1.0 × 10−1 M 2.3-dithiopropanol (BAL) or dithiothreitol (DTT) at 2–4° C for 30 min results in the reduction of the vitamin-K dependent clotting factors II, VII, IX and X to the respective-SH derivatives. The reaction is pH dependent. Under aerobic conditions the delayed one stage prothrombin time can be partly reversed. Under anaerobic conditions a gradual prolongation of the one stage prothrombin time occurs without reversal.In very diluted plasma treated with the dithiols, prothrombin can be converted into thrombin if serum as source of active factors VII and X is added. In contrast SH factors VII, IX and X are inactive in the specific tests. Reoxidation to active factors II, VII, IX and X takes place during adsorption and elution of the SH derivatives. The experiments have indicated that not only factor II but also factors VII, IX and X have active-S-S-centres.

Cervical Myelopathy as a Complication of Untreated Motor Tics: A Cautionary Tale

2020 ◽  
Author(s):  
Mariam Hull ◽  
Mered Parnes
Keyword(s):  
Cervical Myelopathy ◽  
Management Strategies ◽  
Vertebral Artery Dissection ◽  
Tic Disorders ◽  
Artery Dissection ◽  
Cautionary Tale ◽  
Eye Injuries ◽  
Tic Disorder ◽  
Aggressive Management ◽  
Motor Tics

AbstractTic disorders are common, affecting approximately 0.5 to 1% of children and adolescents. Treatment is required only when symptoms are bothersome or impairing to the patient, so many do not require intervention. However, on occasion tics may cause significant morbidity and are referred to as “malignant.” These malignant tics have resulted in cervical myelopathy, subdural hematoma secondary to head banging, biting of lips leading to infection of oral muscles, self-inflicted eye injuries leading to blindness, skeletal fractures, compressive neuropathies, and vertebral artery dissection. We describe a case of malignant tic disorder, with accompanying video segment, resulting in cervical myelopathy and quadriparesis in a child. We also discuss aggressive management strategies for neurologists to prevent potential lifelong disability. This case emphasizes that these malignant tics must be treated with all due haste to prevent such complications.

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