ABSTRACT
An (η5-cyclopentadienyl)cobalt(i) complex was covalently incorporated into an engineered variant of the transmembrane protein ferric hydroxamate uptake protein component: A, FhuA ΔCVFtev, using a thiol-ene reaction. A CD spectrum shows the structural integrity of the biohybrid catalyst. MALDI-TOF of the segment containing the anchoring site for the cobalt complex Cys545 confirmed successful conjugation. This biohybrid catalyst catalyzed the cyclotrimerization of phenylacetylene to give a mixture of regioisomeric 1,2,4- and 1,3,5-triphenylbenzene in aqueous medium.
Subject(s)
Acetylene/analogs & derivatives , Bacterial Outer Membrane Proteins/chemistry , Cobalt/chemistry , Coordination Complexes/chemistry , Escherichia coli Proteins/chemistry , Escherichia coli/chemistry , Acetylene/chemistry , Acetylene/metabolism , Bacterial Outer Membrane Proteins/genetics , Bacterial Outer Membrane Proteins/metabolism , Catalysis , Cyclization , Dimerization , Escherichia coli/genetics , Escherichia coli/metabolism , Escherichia coli Proteins/genetics , Escherichia coli Proteins/metabolism , Ferric Compounds/metabolism , Hydroxamic Acids/metabolism , Models, Molecular , Protein EngineeringABSTRACT
The incorporation of organometallic catalyst precursors in proteins results in so-called artificial metalloenzymes. The protein structure will control activity, selectivity and stability of the organometallic site in aqueous medium and allow non-natural reactions in biological settings. Grubbs-Hoveyda type ruthenium catalysts with an N-heterocyclic carbene (NHC) as ancillary ligand, known to be active in olefin metathesis, have recently been incorporated in various proteins. An overview of these artificial metalloproteins and their potential application in olefin metathesis is given.
Subject(s)
Alkenes/chemistry , Biomimetic Materials/chemistry , Metalloproteins/chemistry , CatalysisABSTRACT
Passive antibody administration is a potentially useful approach for the therapy of human Cryptococcus neoformans infections. To evaluate the efficacy of the human immunoglobulin G1 (IgG1) constant region against C. neoformans and to construct murine antibody derivatives with reduced immunogenicities and longer half-lives in humans, two mouse-human IgG1 chimeric antibodies were generated from the protective murine monoclonal antibodies 2D10 (IgM) and 18B7 (IgG1). The 2D10 mouse-human IgG1 chimeric antibody (ch2D10) had significantly lower binding affinity than its parent murine antibody (m2D10), presumably because of a loss of avidity contribution on switching from IgM to IgG. The 18B7 mouse-human IgG1 chimeric antibody (ch18B7) had higher affinity for cryptococcal polysaccharide antigen than its parent murine antibody (m18B7). ch18B7 and ch2D10 promoted phagocytosis of C. neoformans by primary human microglial cells and the murine J774.16 macrophage-like cell line. ch18B7 and m18B7 enhanced fungistatic or fungicidal activity of J774.16 cells and prolonged the survival of lethally infected mice. We conclude that the human IgG1 constant chain can be effective in mediating antifungal activity against C. neoformans. ch18B7 or similar antibodies are potential candidates for passive antibody therapy of human cryptococcosis.
