Effect of the Hydrophobicity to Net Positive Charge Ratio on Antibacterial and Anti-Endotoxin Activities of Structurally Similar Antimicrobial Peptides

Biochemistry ◽  
2010 ◽  
Vol 49 (5) ◽  
pp. 853-861 ◽  
Author(s):  
Yosef Rosenfeld ◽  
Naama Lev ◽  
Yechiel Shai
Keyword(s):  
Antimicrobial Peptides ◽  
Positive Charge ◽  
Charge Ratio ◽  
Net Positive Charge

scholarly journals The dlt operon confers resistance to cationic antimicrobial peptides in Clostridium difficile

Microbiology ◽  
2011 ◽  
Vol 157 (5) ◽  
pp. 1457-1465 ◽  
Author(s):  
Shonna M. McBride ◽  
Abraham L. Sonenshein
Keyword(s):  
Cell Wall ◽  
Clostridium Difficile ◽  
Antimicrobial Peptides ◽  
Positive Charge ◽  
Polymyxin B ◽  
Gram Positive ◽  
Cationic Antimicrobial Peptides ◽  
Teichoic Acids ◽  
Gram Positive Bacteria ◽  
Net Positive Charge

The dlt operon in Gram-positive bacteria encodes proteins that are necessary for the addition of d-alanine to teichoic acids of the cell wall. The addition of d-alanine to the cell wall results in a net positive charge on the bacterial cell surface and, as a consequence, can decrease the effectiveness of antimicrobials, such as cationic antimicrobial peptides (CAMPs). Although the roles of the dlt genes have been studied for some Gram-positive organisms, the arrangement of these genes in Clostridium difficile and the life cycle of the bacterium in the host are markedly different from those of other pathogens. In the current work, we determined the contribution of the putative C. difficile dlt operon to CAMP resistance. Our data indicate that the dlt operon is necessary for full resistance of C. difficile to nisin, gallidermin, polymyxin B and vancomycin. We propose that the d-alanylation of teichoic acids provides protection against antimicrobial peptides that may be essential for growth of C. difficile in the host.

scholarly journals The mechanism of spray electrification: the waterfall effect

2016 ◽  
Author(s):  
James K. Beattie
Keyword(s):  
Negative Charge ◽  
Positive Charge ◽  
Hydrophobic Hydration ◽  
General Phenomenon ◽  
Aqueous Interfaces ◽  
Preferential Adsorption ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Low Permittivity ◽  
Net Positive Charge

Abstract. The waterfall effect describes the separation of charge by splashing at the base of a waterfall. Smaller drops that have a net negative charge are created, while larger drops and/or the bulk maintain overall charge neutrality with a net positive charge. Since it was first described by Lenard (1892) the effect has been confirmed many times, but a molecular explanation has not been available. Application of our fluctuation-correlation model of hydrophobic hydration accounts for the negative charge observed at aqueous interfaces with low permittivity materials. The negative surface charge observed in the waterfall effect is created by the preferential adsorption of hydroxide ions generated from the autolysis of water. On splashing, shear forces generate small negative drops from the surface, leaving a positive charge on the remaining large fragment. The waterfall effect is a manifestation of the general phenomenon of the negative charge at the interface between water and hydrophobic surfaces that is created by the preferential adsorption of hydroxide ions.

THE EFFECT OF PROCOAGULANT PHOSPHOLIPID VESICLES WITH NET POSITIVE CHARGE ON THE ACTIVITY OF PROTHROMBINASE

1987 ◽  
Author(s):  
J Rosing ◽  
H Speijer ◽  
J W P Govers-Riemslag ◽  
R F A Zwaal
Keyword(s):  
Vitamin K ◽  
Negative Charge ◽  
Positive Charge ◽  
Coagulation Factor ◽  
Phospholipid Vesicles ◽  
Electrostatic Model ◽  
Acidic Phospholipid ◽  
Positively Charged ◽  
Net Positive Charge ◽  
Prothrombin Activation

It is generally thought that procoagulant phospholipid surfaces that promote the activation of vitamin K-dependent coagulation factors should have a net negative charge in order to promote calcium-dependent binding of the enzymes (FVIIa, FIXa and FXa) and substrates (prothrombin and FX) of the coagulation factor-activating complexes. Two models have been proposed to explain calcium-mediated association of vitamin K-dependent proteins with phospholipid: a) an electrostatic model, in which a positively-charged protein-calcium complex is attracted by a negatively-charged phospholipid surface and b) a chelation model in which a coordination complex is formed between calcium ions, γ-carboxyglutamic acids of the proteins and negatively-charged membrane phospholipids. To study the effect of the electrostatic potential of phospholipid vesicles on their activity in the pro-thrombinase complex the net charge of vesicles was varied by introduction of varying amounts of positively-charged stearylamine in the membrane surface. Introduction of 0-15 mole% stearylamine in phospholipid vesicles that contained 5 mole% phosphatidylseri-ne (PS) hardly affected their activity in prothrombin activation. Electrophoretic analysis showed that vesicles with > 5 mole% stearylamine had a net positive charge. The procoagulant activity of vesicles that contained phosphatidic acid, phosphatidylglyce-rol, phosphatidylinositol or phosphatidyl-glactate (PLac) as acidic phospholipid was much more effected by incorporation of stearylamine. Amounts of stearylamine that compensated the negative charge of acidic phospholipid caused considerable inhibition of the activity of the latter vesicles in prothrombin activation. The comparison of vesicles containing PS and PLac as acidic phospholipid is of special interest. PS and PLac only differ by the presence of NH+ 3-group in the serine moiety of PS. Thus, in spite of the fact that vesicles with PLac are more negatively charged than vesicles with PS, they are less procoagulant. Our results show that a) although procoagulant membranes have to contain acidic phospholipids there is no requirement for a net negative charge, b) the amino group of phosphatidylserine has an important function in the interaction of procoagulant membranes with vitamin K-dependent proteins and c) the chelation model can satisfactorily explain calcium-mediated lipid-protein association.

scholarly journals Engineering of Marine-derived Antimicrobial Peptides (mAMPs) into Improved Anti-infective Drug Leads: A Mini-review

2021 ◽  
Vol 1192 (1) ◽  
pp. 012013
Author(s):  
L Sukmarini
Keyword(s):  
Antimicrobial Peptides ◽  
Chemical Diversity ◽  
Cytotoxic Activities ◽  
Small Molecular Weight ◽  
Resistance Development ◽  
Drug Candidates ◽  
Bacteria And Fungi ◽  
Drug Leads ◽  
Net Positive Charge

Abstract Marine-derived antimicrobial compounds possess chemical diversity varying from peptides, fatty acids to terpenes, alkaloids, and polyketides. These compounds, especially of peptide origin called antimicrobial peptides (AMPs), are present in the majority of marine organisms, including microbes (bacteria and fungi), invertebrates (molluscs, echinoderms, and sponges), vertebrates (fish and mammals), and plants (marine algae). They are defined by small molecular weight (less than 10 kDa), a net positive charge, and amphipathic structures. Moreover, due to their profound in vitro antimicrobial and cytotoxic activities and a low risk for resistance development, naturally occurring marine-derived AMPs (mAMPs) have been used as drug design templates for a large variety of semi-synthetic or synthetic AMPs, some of which have reached clinical trials. This mini-review aims to discuss AMPs from marine sources, mainly emphasizing the engineering of these peptides with improved pharmacological properties to develop drug candidates. Some selected recent examples of these engineered mAMPs as anti-infective drug leads are herein highlighted.

scholarly journals Chloride net efflux from intact erythrocytes under slippage conditions. Evidence for a positive charge on the anion binding/transport site.

1983 ◽  
Vol 81 (1) ◽  
pp. 127-152 ◽  
Author(s):  
O Fröhlich ◽  
C Leibson ◽  
R B Gunn
Keyword(s):  
Conformational Changes ◽  
Positive Charge ◽  
Chloride Ion ◽  
Anion Binding ◽  
Maximal Inhibition ◽  
Exchange Inhibitor ◽  
Anion Transporter ◽  
Transport Site ◽  
Chloride Concentrations ◽  
Net Positive Charge

Tracer chloride and potassium net efflux from valinomycin-treated human erythrocytes were measured into media of different chloride concentrations, Clo, at 25 degrees C and pH 7.8. Net efflux was maximal [45-50 mmol (kg cell solids)-1 min-1] at Clo = 0. It decreased hyperbolically with increasing Clo to 14-16 mmol (kg cell solids)-1 min-1. Half-maximal inhibition occurred at Clo = 3 mM. In the presence of the anion exchange inhibitor DNDS, net efflux was reduced to 5 mmol (kg cell solids)-1 min-1, independent of Clo. Of the three phenomenological components of net efflux, the Clo-inhibitable (DNDS-inhibitable) component was tentatively attributed to "slippage," that is, net transport mediated by the occasional return of the empty transporter. The Clo-independent (DNDS-inhibitable) component was tentatively attributed to movement of chloride through the anion transporter without the usual conformational change of the transport site on the protein ("tunneling"). These concepts of slippage and tunneling are shown to be compatible with a model that describes the anion transporter as a specialized single-site, two-barrier channel that can undergo conformational changes between two states. Net chloride efflux when the slippage component dominated (Clo = 0.7 mM) was accelerated by a more negative (inside) membrane potential. It appears that the single anion binding-and-transport site on each transporter has one net positive charge and that is neutralized when a chloride ion is bound.

scholarly journals A CYTOCHEMICAL STUDY OF CYTOPLASMIC BASIC PROTEINS IN THE ASCIDIAN OOCYTE

1965 ◽  
Vol 25 (2) ◽  
pp. 319-326 ◽  
Author(s):  
Richard Davenport ◽  
Janice C. Davenport
Keyword(s):  
Positive Charge ◽  
Amino Groups ◽  
Acid Dyes ◽  
Fast Green ◽  
Cytochemical Study ◽  
Basic Proteins ◽  
Protein Molecules ◽  
Nucleoprotein Complex ◽  
High Concentrations ◽  
Net Positive Charge

The cytoplasm of young oocytes of the ascidians contains high concentrations of proteins which are stainable with alkaline fast green at pH 8.1 and above. These proteins cannot be stained even with acid dyes at low pH unless RNA is removed. Deamination and formalin blockage of amino groups is incapable of destroying the net positive charge on these protein molecules in the presence of RNA, but these treatments destroy the charge if RNA is removed. It is therefore concluded that basic proteins and RNA exist as a nucleoprotein complex in the ribosomes of these young oocytes. The detectable RNA of the mature oocytes and unfertilized eggs shows no evidence of being associated with basic proteins.

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