Antimicrobial Peptide K11 Selectively Recognizes Bacterial Biomimetic Membranes and Acts by Twisting Their Bilayers

K11 is a synthetic peptide originating from the introduction of a lysine residue in position 11 within the sequence of a rationally designed antibacterial scaffold. Despite its remarkable antibacterial properties towards many ESKAPE bacteria and its optimal therapeutic index (320), a detailed description of its mechanism of action is missing. As most antimicrobial peptides act by destabilizing the membranes of the target organisms, we investigated the interaction of K11 with biomimetic membranes of various phospholipid compositions by liquid and solid-state NMR. Our data show that K11 can selectively destabilize bacterial biomimetic membranes and torque the surface of their bilayers. The same is observed for membranes containing other negatively charged phospholipids which might suggest additional biological activities. Molecular dynamic simulations reveal that K11 can penetrate the membrane in four steps: after binding to phosphate groups by means of the lysine residue at the N-terminus (anchoring), three couples of lysine residues act subsequently to exert a torque in the membrane (twisting) which allows the insertion of aromatic side chains at both termini (insertion) eventually leading to the flip of the amphipathic helix inside the bilayer core (helix flip and internalization).

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The Action of Thrombin on Modified Fibrinogen

Thrombosis and Haemostasis ◽

10.1055/s-0038-1657364 ◽

1983 ◽

Vol 49 (03) ◽

pp. 208-213

Author(s):

A J Osbahr

Keyword(s):

Physical Properties ◽

Negative Charge ◽

Lysine Residue ◽

Fibrinopeptide A ◽

Amino Groups ◽

Lysine Residues ◽

Citraconic Anhydride

SummaryThe modification of canine fibrinogen with citraconic anhydride modified the ε-amino groups of the fibrinogen and at the same time generated additional negative charges into the protein. The addition of thrombin to the modified fibrinogen did not induce polymerization; however, the fibrinopeptide was released at a faster rate than from the unmodified fibrinogen. The physical properties of the citraconylated fibrinogen were markedly altered by the modification of 50-60 lysine residues in one hour. A modified fibrinopeptide-A was released by thrombin from the modified fibrinogen and was electrophoretically more anionic than the unmodified fibrinopeptide-A. Edman analysis confirmed the modification of the lysine residue present in the peptide. The rate of removal of citraconylated fibrinopeptide-A from modified fibrinogen by thrombin was 30 to 40 percent greater than the cleavage of unmodified fibrinopeptide-A from unmodified fibrinogen. However, the modification of 60 or more lysine residues in the fibrinogen produced a decrease in the rate of cleavage of citraconylated fibrinopeptide-A. The results suggest that additional negative charge in the vicinity of the attachment of fibrinopeptide-A to canine fibrinogen aids in the removal of the peptide by thrombin.

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Snail mucus from the mantle and foot of two land snails, Lissachatina fulica and Hemiplecta distincta, exhibits different protein profile and biological activity

BMC Research Notes ◽

10.1186/s13104-021-05557-0 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Nattaphop Noothuan ◽

Kantamas Apitanyasai ◽

Somsak Panha ◽

Anchalee Tassanakajon

Keyword(s):

Biological Activities ◽

Protein Pattern ◽

Protein Profile ◽

Antibacterial Properties ◽

Biological Properties ◽

Specific Protein ◽

Land Snails ◽

Snail Species ◽

Significant Difference ◽

Different Types

Abstract Objective Snails secrete different types of mucus that serve several functions, and are increasingly being exploited for medical and cosmetic applications. In this study, we explored the protein pattern and compared the biological properties of the mucus secreted from the mantle collar and foot of two snail species, Lissachatina fulica and Hemiplecta distincta. Result Protein profile showed a different pattern between the two species and between the two secretory parts. The mantle-specific protein bands were further characterized and among them was an antibacterial protein, achacin. Accordingly, the mucus from the mantle exhibited the higher antibacterial activity than that from the foot in both snail species. The mucus from H. distincta, first reported here, also showed antibacterial properties, but with a lower activity compared to that for L. fulica. Snail mucus also exhibited anti-tyrosinase activity and antioxidant activity but with no significant difference between the foot and mantle mucus. These results indicate some different protein compositions and biological activities of snail slime from the mantle and foot, which might be associated with their specific functions in the animal and are useful for medical applications.

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Horse liver alcohol dehydrogenase. A study of the essential lysine residue

Biochemical Journal ◽

10.1042/bj1490627 ◽

1975 ◽

Vol 149 (3) ◽

pp. 627-635 ◽

Cited By ~ 17

Author(s):

S S Chen ◽

P C Engel

Keyword(s):

Alcohol Dehydrogenase ◽

Rate Constant ◽

Lysine Residue ◽

Horse Liver Alcohol Dehydrogenase ◽

First Order ◽

Liver Alcohol Dehydrogenase ◽

Horse Liver ◽

Lysine Residues ◽

Modified Enzyme ◽

Covalent Complex

1. The inactivation of horse liver alcohol dehydrogenase by pyridoxal 5'-phosphate in phosphate buffer, pH8, at 10°C was investigated. Activity declines to a minimum value determined by the pyridoxal 5'-phosphate concentration. The maximum inactivation in a single treatment is 75%. This limit appears to be set by the ratio of the first-order rate constants for interconversion of inactive covalently modified enzyme and a readily dissociable non-covalent enzyme-modifier complex. 2. Reactivation was virtually complete on 150-fold dilution: first-order analysis yielded an estimate of the rate constant (0.164min-1), which was then used in the kinetic analysis of the forward inactivation reaction. This provided estimates for the rate constant for conversion of non-covalent complex into inactive enzyme (0.465 min-1) and the dissociation constant of the non-covalent complex (2.8 mM). From the two first-order constants, the minimum attainable activity in a single cycle of treatment may be calculated as 24.5%, very close to the observed value. 3. Successive cycles of modification followed by reduction with NaBH4 each decreased activity by the same fraction, so that three cycles with 3.6 mM-pyridoxal 5'-phosphate decreased specific activity to about 1% of the original value. The absorption spectrum of the enzyme thus treated indicated incorporation of 2-3 mol of pyridoxal 5'-phosphate per mol of subunit, covalently bonded to lysine residues. 4. NAD+ and NADH protected the enzyme completely against inactivation by pyridoxal 5'-phosphate, but ethanol and acetaldehyde were without effect. 5. Pyridoxal 5'-phosphate used as an inhibitor in steady-state experiments, rather than as an inactivator, was non-competitive with respect to both NADH and acetaldehyde. 6. The partially modified enzyme (74% inactive) showed unaltered apparent Km values for NAD+ and ethanol, indicating that modified enzyme is completely inactive, and that the residual activity is due to enzyme that has not been covalently modified. 7. Activation by methylation with formaldehyde was confirmed, but this treatment does not prevent subsequent inactivation with pyridoxal 5'-phosphate. Presumably different lysine residues are involved. 8. It is likely that the essential lysine residue modified by pyridoxal 5'-phosphate is involved either in binding the coenzymes or in the catalytic step. 9. Less detailed studies of yeast alcohol dehydrogenase suggest that this enzyme also possesses an essential lysine residue.

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Chemical Footprinting Reveals Conformational Changes Following Activation of Factor XI

Thrombosis and Haemostasis ◽

10.1160/th17-09-0676 ◽

2018 ◽

Vol 118 (02) ◽

pp. 340-350 ◽

Cited By ~ 3

Author(s):

Ingrid Stroo ◽

J. Marquart ◽

Kamran Bakhtiari ◽

Tom Plug ◽

Alexander Meijer ◽

...

Keyword(s):

Conformational Change ◽

Conformational Changes ◽

Catalytic Domain ◽

Active Form ◽

Coagulation Factor ◽

Lysine Residue ◽

Factor Ix ◽

Factor Xi ◽

Lysine Residues ◽

Factor Xia

AbstractCoagulation factor XI is activated by thrombin or factor XIIa resulting in a conformational change that converts the catalytic domain into its active form and exposing exosites for factor IX on the apple domains. Although crystal structures of the zymogen factor XI and the catalytic domain of the protease are available, the structure of the apple domains and hence the interactions with the catalytic domain in factor XIa are unknown. We now used chemical footprinting to identify lysine residue containing regions that undergo a conformational change following activation of factor XI. To this end, we employed tandem mass tag in conjunction with mass spectrometry. Fifty-two unique peptides were identified, covering 37 of the 41 lysine residues present in factor XI. Two identified lysine residues that showed altered flexibility upon activation were mutated to study their contribution in factor XI stability or enzymatic activity. Lys357, part of the connecting loop between A4 and the catalytic domain, was more reactive in factor XIa but mutation of this lysine residue did not impact on factor XIa activity. Lys516 and its possible interactor Glu380 are located in the catalytic domain and are covered by the activation loop of factor XIa. Mutating Glu380 enhanced Arg369 cleavage and thrombin generation in plasma. In conclusion, we have identified novel regions that undergo a conformational change following activation. This information improves knowledge about factor XI and will contribute to development of novel inhibitors or activators for this coagulation protein.

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Antioxidant and Antimicrobial Activities of the Fresh aerial parts of Ammi visnaga L. from Algeria

South Asian Journal of Experimental Biology ◽

10.38150/sajeb.6(2).p70-76 ◽

2016 ◽

Vol 6 (2) ◽

pp. 70-76

Author(s):

Soumia Keddari ◽

Narimen Benaoum ◽

Yasmina Mokhtaria Boufadi ◽

Mansouria Belhocine ◽

Ali Riazi

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Activity ◽

Phenolic Compounds ◽

Biological Activities ◽

Antibacterial Properties ◽

Ethanolic Extract ◽

Diffusion Method ◽

E Coli ◽

Ammi Visnaga ◽

Wide Range

Medicinal plants have been used for countries as cures for human diseases because they contain components of therapeutic value. Among these medi-cinal plants, Ammi visnage which have an immense reservoir of potential compounds attributed to the secondary metabolites which have the advan-tage of being of great diversity of chemical structure and have a very wide range of biological activities. The objectives of the present work were to stu-dy the antioxidant and antimicrobial activity of phenolic compounds ex-tracted from A. visnaga L. Its extraction is performed by two methods, etha-nol extraction and water extraction. The results showed that A. visnaga L.. ethanolic extract contains a mixture of phytochemical classes as polyphenol, flavonoids and revealed that this plant has high antioxidant activity (IC50 0.069 mg/ml). Regarding the antimicrobial activity results expressed by the diameter of the inhibition zones by diffusion method AWDT, the most signifi-cant inhibition was observed against to Staphylococcus aureus (12 mm) to the ethanol extract at concentration of 100mg / ml. Thus the aqueous ex-tract had a significant inhibitory activity against on the strains Staphylococ-cus aureus (8 mm), E. coli ATCC 10536 (8 mm) to a concentration of 100 mg / ml. The results for the antibacterial properties have shown that Gram-positive bacteria (Staphylococcus aureus, Listeria monocytogenes and M. luteus.) were more sensitive than gram-negative (Pseudomonas aeruginosa, E. coli ATCC 10536) against from the action of phenolic compounds of the Ammi visnaga ethanolic extract.

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Potential Antimicrobial and Anticancer Activities of an Ethanol Extract from Bouea macrophylla

Molecules ◽

10.3390/molecules25081996 ◽

2020 ◽

Vol 25 (8) ◽

pp. 1996 ◽

Cited By ~ 3

Author(s):

Ngoc Hong Nguyen ◽

Thuy Trang Nguyen ◽

Phu Cuong Ma ◽

Qui Thanh Hoai Ta ◽

Thuc-Huy Duong ◽

...

Keyword(s):

Biological Activities ◽

Chemical Constituents ◽

Shigella Flexneri ◽

Folk Medicine ◽

Antibacterial Properties ◽

Ethanol Extract ◽

Anticancer Activities ◽

Ic50 Values ◽

Bacteria And Fungi ◽

Hct116 Cells

Bouea macrophylla is a tree widely grown throughout South East Asia. It is used in folk medicine for the treatment of various illnesses. The present study aimed to identify the chemical constituents and to test the antimicrobial and anticancer activities of an ethanol extract from B. macrophylla leaves. The extract exhibited excellent antibacterial properties against 9 out of 10 target microorganisms. including four Gram-negative bacteria (Escherichia coli, Shigella flexneri, Vibrio cholera, and Pseudomonas aeruginosa) and four Gram-positive bacteria (Staphylococcus aureus, Listeria monocytogenes, Enterococcus faecalis, and Bacillus cereus), as well as a fungus (Candida albicans). In addition, the extract was also tested on HeLa and human colorectal carcinoma (HCT116) cells to evaluate its cytostatic effects. The ethanol extract was able to inhibit the proliferation of HeLa and HCT116 cells, showing IC50 = 24 ± 0.8 and 28 ± 0.9 µg/mL, respectively, whereas the IC50 values of doxorubicin (standard) were 13.6 ± 1.3 and 15.8 ± 1.1 µg/mL respectively. Also, we identified various bioactive compounds in the extract such as polyphenols, flavonoids, caryophyllene, phytol, and trans-geranylgeraniol by GC-MS, which could contribute to the extract’s biological activities. Therefore, our findings strongly indicate that the constituents of the B. macrophylla ethanol extract could be active against the tested bacteria and fungi as well as cancer cells. Further investigation is needed to understand the mechanisms mediating the antimicrobial and anticancer effects and identify signaling pathways that could be targeted for therapeutic application.

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Modification of pig M4 lactate dehydrogenase by pyridoxal 5'-phosphate. Demonstration of an essential lysine residue

Biochemical Journal ◽

10.1042/bj1490107 ◽

1975 ◽

Vol 149 (1) ◽

pp. 107-113 ◽

Cited By ~ 13

Author(s):

S S Chen ◽

P C Engel

Keyword(s):

Lactate Dehydrogenase ◽

Equilibrium Mixture ◽

Lysine Residue ◽

Original Activity ◽

Complete Inactivation ◽

Lysine Modification ◽

Covalently Bonded ◽

Lysine Residues ◽

Enzyme Protection ◽

Schiff Base Formation

1. Pig M4 lactate dehydrogenase treated in the dark with pyridoxal 5'-phosphate at pH8.5 and 25 degrees C loses activity gradually. The maximum inactivation was 66%, and this did not increase with concentrations of pyridoxal 5'-phosphate above 1 mM. 2. Inactivation may be reversed by dialysis or made permanent by reducing the enzyme with NaBH4. 3. Spectral evidence indicates modification of lysine residues, and 6-N-pyridoxyl-lysine is present in the hydrolsate of inactivated, reduced enzyme. 4. A second cycle of treatment with pyridoxal 5'-phosphate and NaBH4 further decreases activity. After three cycles only 9% of the original activity remains. 5. Apparent Km values for lactate and NAD+ are unaltered in the partially inactivated enzyme. 6. These results suggest that the covalently modified enzyme is inactive; failure to achieve complete inactivation in a single treatment is due to the reversibility of Schiff-base formation and to the consequent presence of active non-covalently bonded enzyme-modifier complex in the equilibrium mixture. 7. Although several lysine residues per subunit are modified, only one appears to be essential for activity: pyruvate and NAD+ together (both 5mM) completely protect against inactivation, and there is a one-to-one relationship between enzyme protection and decreased lysine modification. 8. NAD+ or NADH alone gives only partial protection. Substrates give virtually none. 9. Pig H4 lactate dehydrogenase is also inactivated by pyridoxal 5'-phosphate. 10. The possible role of the essential lysine residue is discussed.

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The B-Domain Lysine Patch of pRB Is Required for Binding to Large T Antigen and Release of E2F by Phosphorylation

Molecular and Cellular Biology ◽

10.1128/mcb.22.5.1390-1401.2002 ◽

2002 ◽

Vol 22 (5) ◽

pp. 1390-1401 ◽

Cited By ~ 14

Author(s):

Vivette D. Brown ◽

Brenda L. Gallie

Keyword(s):

Simian Virus 40 ◽

Simian Virus ◽

T Antigen ◽

Large T Antigen ◽

Cyclin Dependent Kinases ◽

Lysine Residues ◽

Dependent Site ◽

Cycle Dependent ◽

Phosphate Groups ◽

Positively Charged

ABSTRACT Cell cycle-dependent, site-specific phosphorylation of the retinoblastoma protein, pRB, is mediated by cyclin-dependent kinases (CDKs) and regulates the binding of pRB to many proteins. We previously showed that the interaction of pRB with E2F on DNA was regulated by the accumulation of phosphate groups on pRB. Here we show that positively charged lysine residues in the B domain of pRB are necessary for the release of pRB from E2F on DNA following phosphorylation by cyclin E-cdk2 kinase. These lysine residues are also important in the binding of the simian virus 40 large T antigen (TAg) to pRB, and mutation of these lysines to arginines alters the dependency of the pRB-TAg interaction on phosphorylation of pRB.

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Antibacterial Effect of Graphene and Graphene Oxide as a Potential Material for Fiber Finishes

Autex Research Journal ◽

10.2478/aut-2020-0009 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Anna Olborska ◽

Anna Janas-Naze ◽

Łukasz Kaczmarek ◽

Tomasz Warga ◽

Dewi Suriyani Che Halin

Keyword(s):

Antimicrobial Agents ◽

Growth Parameters ◽

Antibacterial Properties ◽

The Body ◽

Physical Interaction ◽

Dynamic Simulations ◽

Antibiotic Resistant ◽

Internal Cell ◽

Unique Method ◽

Additive Materials

AbstractThe dynamic development of the world economy entails an increasing exchange of goods and population. This means that we are globally struggling with increasing levels of nosocomial infections. The increasing use of antimicrobial agents triggers the microorganisms’ immune system, which in turn contributes to the increasing amount of antibiotic-resistant microorganisms, making it necessary to control the development of unwanted microorganisms, including bacteria, especially those carried on the body and clothing.Currently, there is no unique method to combat the multiplication of microorganisms and eliminate threats to human health and life. For this reason, this article describes the possibilities of using graphene materials as a potential additive materials in fiber finishes as an antibacterial aspect in various areas of life. However, the literature does not explain the mechanisms behind the antibacterial properties of graphene, strongly limiting its textile application. The research is conducted using molecular dynamic simulations of interaction between graphene materials and murein. The obtained results suggest the electrostatic mechanism of blocking the growth and division of bacteria. Due to the physical interaction, bacterial cell becomes “trapped” without changing its growth parameters. This may lead to an increase of internal cell pressure, rupture of its wall and consequently its death.

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Algae Polyphenolic Compounds and Modern Antibacterial Strategies: Current Achievements and Immediate Prospects

Biomedicines ◽

10.3390/biomedicines8090342 ◽

2020 ◽

Vol 8 (9) ◽

pp. 342 ◽

Cited By ~ 1

Author(s):

Natalya N. Besednova ◽

Boris G. Andryukov ◽

Tatyana S. Zaporozhets ◽

Sergey P. Kryzhanovsky ◽

Tatyana A. Kuznetsova ◽

...

Keyword(s):

Antimicrobial Activity ◽

Antimicrobial Agents ◽

Biological Activities ◽

Antibacterial Properties ◽

Structural Diversity ◽

Polyphenolic Compounds ◽

High Antimicrobial Activity ◽

Functional Relationships ◽

Treatment And Prevention ◽

Polyfunctional Compounds

The increasing drug resistance of pathogenic microorganisms raises concern worldwide and necessitates the search for new natural compounds with antibacterial properties. Marine algae are considered a natural and attractive biotechnological source of novel antibiotics. The high antimicrobial activity of their polyphenolic compounds is a promising basis for designing innovative pharmaceuticals. They can become both a serious alternative to traditional antimicrobial agents and an effective supplement to antibiotic therapy. The present review summarizes the results of numerous studies on polyphenols from algae and the range of biological activities that determine their biomedical significance. The main focus is put on a group of the polyphenolic metabolites referred to as phlorotannins and, particularly, on their structural diversity and mechanisms of antimicrobial effects. Brown algae are an almost inexhaustible resource with a high biotechnological potential for obtaining these polyfunctional compounds. An opinion is expressed that the effectiveness of the antibacterial activity of phlorotannins depends on the methods of their extraction aimed at preserving the phenolic structure. The use of modern analytical tools opens up a broad range of opportunities for studying the metabolic pathways of phlorotannins and identifying their structural and functional relationships. The high antimicrobial activity of phlorotannins against both Gram-positive and Gram-negative bacteria provides a promising framework for creating novel drugs to be used in the treatment and prevention of infectious diseases.

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