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Achraf Hikmat Kouzayha

Associate professor
Chemistry - Biochemistry department - Section III - Tripoli
Speciality: Biochemistry
Specific Speciality: Biochimie génie enzymatique

Positions
Teaching 8 Taught Courses
(2014-2015) Bioc 415 - Fundamental Microbial Biochemistry

M1 Biochemistry

(2014-2015) Bioc 416 - Fundamental Microbial Biochemistry Lab

M1 Biochemistry

(2014-2015) Bioc 416 - Fundamental Microbial Biochemistry Lab

M1 Biochemistry

(2014-2015) Bioc 406 - Enterprises and socioeconomic fabrics

M1 Biochemistry

(2014-2015) Bioc 407 - Cell Signaling

M1 Biochemistry

(2014-2015) Bioc 429 - Applied Microbiology

M1 Biochemistry

(2014-2015) Bioc 331 - Modulation of Protein function

BS Biochemistry

(2014-2015) Bioc 381 - Metabolic Biochemistry Lab

BS Earth and life sciences

Education
2005 - 2009: Ph.D.

Université de Picardie Jules Verne - Amiens/ France

2004 - 2005: Master's Biochemistry

Université Claude Bernard Lyon 1 / France

1999 - 2004: M1 Biochemistry

Université Claude Bernard Lyon 1 / France

Publications 7 publications
C. Accary, M. Rima, A. Kouzayha, W. Hleihel, Jean Claude Desfontis, Z. Fajloun, S. Hraoui-Bloquet Effect of the Montivipera bornmuelleri snake venom on human blood: coagulation disorders and hemolytic activities Open Journal of Hematology 2014

Viper’s venom is a source of biopharmaceutical compounds, hence the need to assess the effect of this animal extract on human blood. Here, we studied the blood coagulation disorders and hemolytic activities of the venom of M. bornmulleri viper. The pro-coagulant and anticoagulant effects are analyzed with venom concentrations ranging from 0.4 to 0.0031 mg/mL. Thus, the PT is way above the normal value indicating an anticoagulant activity whereas for the aPTT, the high concentration of the venom showed an anticoagulant activity, but a pro-coagulant effect was occurred when the venom concentration decreases to 0.05 and/or 0.025 mg/mL. Hemolytic tests, performed in suspension (30% RBCs) and on blood agar plate (5% RBCs), show that an increased concentration of the venom going until 1.6 mg cannot produce a hemolytic effect, even in the presence of Ca2+ (hemolysis < 0.5%). Also, on the blood agar plate no hemolytic area appeared even with 0.04 mg of the lyophilized venom. Otherwise, the venom was able to induce a low hemolytic activity (hemolysis = 1.3 %) by acting on L-α-PC used as substrate. In this case, the destruction of erythrocytes increased proportionally to the added amount of phospholipids which are hydrolyzed to fatty acids and lysophospholipids (two toxic substances for RBCs), probably due to the presence of PLA2 in the venom and which are known by their ability to hydrolyze lecithin.

S. K. Nguikwiea, M. A. Nyeguea, F. N. Belingaa, R. A. Nganeb, B. Romestand, A. Kouzayha, H. Casabianca, P. H. Zolloa and C. Menut The Chemical Composition and Antibacterial Activities of the Essential Oils from Three Aframomum Species from Cameroon, and Their Potential as Sources of (E)-(R)-Nerolidol Natural Product Communications 2013

Essential oils obtained by hydrodistillation of seeds, pericarps, leaves and rhizomes of Aframomum dalzielii, A. letestuianum and A. pruinosum grown in Cameroon were analyzed by GC-FID and GC-MS. The seed oils of the three species were characterized by a high content of (E)-(R)-nerolidol (>88.0 %), which was fully characterized by NMR spectroscopy and chiral GC analysis. The main constituents of the pericarp and rhizome oils were monoterpene hydrocarbons, mainly beta-pinene (0.8%-22.9%) and sabinene (29.0%-42.3%), along with 1,8-cineole (4.5%-23.7%); leaf oils were characterized by sesquiterpenes, namely (E)-beta-caryophyllene (18.4%-82.4%) and caryophyllene oxide (4.5%-23.7%). The antibacterial activities of these essential oils and of nine pure compounds (sabirtene, beta-pinene, 1,8-cineole, linalool, racemic (E)-nerolidol, (E)-(R)-nerolidol, (E)-beta-caryophyllene, a-humulene and caryophyllene oxide) were assessed against Micrococcus luteus and Escherichia coli. The strongest activities were observed against E. coli. The seed essential oils and their major component, (E)-(R)-nerolidol, exhibited the lowest MIC values (0.19-0.39 mu L/mL), justifying their traditional use and their potential application as natural food preservatives.

J. Guezennec, J. M. Herry, A. Kouzayha, E. Bachere, M. W. Mittelman, M. N. Bellon Fontaine Exopolysaccharides from unusual marine environments inhibit early stages of biofouling International Biodeterioration & Biodegradation 2012

Biological fouling in marine and freshwater environments creates a number of problems for engineered structures. The deleterious effects arise from microbial biofilm formation, often followed by successional colonization by a variety of macrofouling organisms. To-date, effective prevention strategies have primarily relied upon antimicrobial agents that usually show toxicity against non-target organisms. While a variety of non-toxic surface modification technologies have been employed, their efficacy has been very limited in in situ environments. We evaluated a number of extracellular polysaccharide (EPS) formulations purified from marine bacteria as potential antifouling agents. EPS from Alteromonas, Pseudomonas, and Vibrio spp. were dip-coated onto cleaned glass slides, placed into a flow cell apparatus with real-time imaging, then exposed to natural flowing seawater under laboratory conditions over a 5 d timeframe. All six of the purified EPS formulations inhibited biofouling (primarily, bacteria) over the test period, with HYD 657, HE 800, HYD 1644 and HYD 1545 showing the most significant reductions in fouling. Surface area fouling was reduced by 90% relative to a cleaned glass control substrate. None of the six formulations evaluated showed any evidence of antimicrobial activity or of cytotoxicity. While the mechanism(s) responsible for the observed fouling inhibition are not fully resolved, it is possible that steric hindrance of primary colonizers may be involved. These preliminary results suggest that bacterial EPS may be an effective inhibitor of the initial stages of biofilm formation and subsequent biofouling activity.

M. N. Nasir, A. Thawani, A. Kouzayha, F. Besson Interactions of the natural antimicrobial mycosubtilin with phospholipid membrane models Colloids and Surfaces B: Biointerfaces 2010

Among the secondary metabolite lipopeptides produced by Bacillus subtilis, mycosubtilin is characterized by its strong antifungal activities. Even though its structure and its cellular target, the cytoplasmic membrane, have been determined, the molecular mechanisms of the biological activity of mycosubtilin have not been completely elucidated. In this work, the interactions between mycosubtilin and cytoplasmic membranes were modelled by using biomimetic systems such as Langmuir monolayers at the air–water interface and lipid multilamellar vesicles. The interactions of mycosubtilin with these biomimetic systems were examined, for the first time, by using specific techniques such as polarization modulation infrared reflection absorption spectroscopy, Brewster angle microscopy and high-resolution magic angle spinning NMR. Our findings indicate that mycosubtilin alone, at the air–water interface, forms a monolayer film and keeps its turn conformation. In the presence of DMPC, mycosubtilin binds to phospholipid monolayers, in a surface pressure-dependent manner. This binding results in the appearance of condensed domains which can be due to the formation of mycosubtilin clusters and/or to the lipopeptide aggregation with some phospholipid molecules and/or the formation of liquid-condensed domains of DMPC. Furthermore, in multilamellar vesicles, the mycosubtilin–DMPC interactions take place at the level of the aliphatic chains of the phospholipid because the phase transition temperature of DMPC decreased in the presence of mycosubtilin.

A. Kouzayha, M. N. Nasir, R. Buchet, O. Wattraint, C. Sarazin, F. Besson Conformational and interfacial analyses of K3A18K3 and alamethicin in model membranes J. Phys. Chem. B 2009

The involvement of membrane-bound peptides and the influence of protein conformations in several neurodegenerative diseases lead us to analyze the interactions of model peptides with artificial membranes. Two model peptides were selected. The first one, an alanine-rich peptide, K3A18K3, was shown to be in α-helix structures in TFE, a membrane environment-mimicking solvent, while it was mostly β-sheeted in aqueous buffer as revealed by infrared spectroscopy. The other, alamethicin, a natural peptide, was in a stable α-helix structure. To determine the role of the peptide conformation on the nature of its interactions with lipids, we compared the structure and topology of the conformational-labile peptide K3A18K3 and of the α-helix rigid alamethicin in both aqueous and phospholipid environments (Langmuir monolayers and multilamellar vesicles). K3A18K3 at the air−water interface showed a pressure-dependent orientation of its β-sheets, while the α-helix axis of alamethicin was always parallel to the interface, as probed by polarization modulation infrared reflection absorption spectroscopy. The β-sheeted K3A18K3 peptide was uniformly distributed into DPPC condensed domains, while the helical-alamethicin insertion distorted the DPPC condensed domains, as evidenced by Brewster angle microscopy imaging of the air/interface. The β-sheeted K3A18K3 interacted with DMPC multilamellar vesicles via hydrophilic interactions with polar heads and the helical-alamethicin via hydrophobic interactions with alkyl chains, as shown by infrared spectroscopy and solid state NMR. Our findings are consistent with the prevailing assumption that the conformation of the peptide predetermines the mode of interaction with lipids. More precisely, helical peptides tend to be inserted via hydrophobic interactions within the hydrophobic region of membranes, while β-sheeted peptides are predisposed to interact with polar groups and stay at the surface of lipid layers.

A. Kouzayha, O. Wattraint, C. Sarazin Interactions of two transmembranes peptides on supported lipid bilayers studied by a 31P and 15N MAOSS NMR strategy Biochimie 2009

31P and 15N solid-state NMR with the magic angle-oriented sample spinning (MAOSS) strategy was used to investigate the effect of two model peptides on phospholipid bilayers mimicking biological membrane. One of the peptides, alamethicin, used as a reference of transmembrane alignment, has been shown to disrupt the lipid bilayer organisation, affecting the DMPC packaging. On the other hand, a α-helix alanine-rich peptide, K3A18K3, with a 15N labelled alanine, did not present any effect in the DMPC bilayer organisation. The mean orientation of this peptide in the bilayer gave a transmembrane alignment of about 80%.

A. Kouzayha, F. Besson GPI-alkaline phosphatase insertion into phosphatidylcholine monolayers: Phase behavior and morphology changes Biochem. Biophys. Res. Commun. 2005

GPI-anchored proteins are localized on the outer layer of plasma membranes and clustered in microdomains generally called lipid rafts. To study the interactions between the lipidic GPI-anchor of the protein and phospholipids, we used phosphatidylcholine monolayers at the air–water interface as a biomimetic membrane system and GPI-alkaline phosphatase prepared from bovine intestinal mucosa (GPI–BIAP) as an GPI-anchored protein model. The monolayer technique allowed us to define GPI–BIAP interaction with DPPC and POPC, lipids differing only by the presence of one unsaturation in their acyl chains. Meanwhile the exclusion pressures were similar for the two phospholipids, the comparison of the Langmuir isotherms (i.e., pressure/area diagrams) indicates that GPI–BIAP interacted differently with DPPC and POPC monolayers. BAM images, acquired in order to visualize the interface organization induced by GPI–BIAP incorporation, confirm these differences.

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Arabic

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English

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French

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