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البحوث العلمية

2018

Defined covalent assembly of protein molecules on graphene using a genetically encoded photochemical reaction handle

2018-02
RSC Adv (القضية : 11) (الحجم : 8)
We have created modified protein variants by introducing a non-canonical amino acid p-azido-L-phenylalanine (azF) into defined positions for photochemically-induced covalent attachment to graphene. Attachment of GFP, TEM and cyt b562 proteins was verified through a combination of atomic force and scanning tunnelling microscopy, resistance measurements, Raman data and fluorescence measurements. This method can in principle be extended to any protein which can be engineered in this way without adversely affecting its structural stability.
2015

Functional modulation and directed assembly of an enzyme through designed non-natural post-translation modification

2015-03
Chem. Sci. (القضية : 7) (الحجم : 6)
Post-translational modification (PTM) modulates and supplements protein functionality. In nature this high precision event requires specific motifs and/or associated modification machinery. To overcome the inherent complexity that hinders PTM's wider use, we have utilized a non-native biocompatible Click chemistry approach to site-specifically modify TEM b-lactamase that adds new functionality. In silico modelling was used to design TEM b-lactamase variants with the non-natural amino acid p-azido-Lphenylalanine (azF) placed at functionally strategic positions permitting residue-specific modification with alkyne adducts by exploiting strain-promoted azide–alkyne cycloaddition. Three designs were implemented so that the modification would: (i) inhibit TEM activity (Y105azF); (ii) restore activity compromised by the initial mutation (P174azF); (iii) facilitate assembly on pristine graphene (W165azF). A dibenzylcyclooctyne (DBCO) with amine functionality was enough to modulate enzymatic activity. Modification of TEMW165azF with a DBCO–pyrene adduct had little effect on activity despite the modification site being close to a key catalytic residue but allowed directed assembly of the enzyme on graphene, potentially facilitating the construction of protein-gated carbon transistor systems.
2009

Effect of Magnetic Field on the Radial Distribution of Plasma Parameters in Cylendrical Air Glow Discharge

2009-06
J. Duhok Univ. (القضية : 2) (الحجم : 12)
Direct measurements of the radial distribution of the discharge current density and electron energy distribution function in dc air plasma discharges are carried out.

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