Gram-positive Rhodococcus Opacus Research Articles

Finding the Relationship Between the Biological Dagradtion Rate Constants and Some of the Calculated Physical Properties of a Number of Carcinogenic poly Aromatic Hydrocarbons

This study involves the theoretical calculation of binding energy (the free energy ΔG°) of eleven of polycyclic aromatic hydrocarbons (PAHs) compounds with catechol 1,2-dioxygenase enzyme from the gram-positive Rhodococcus opacus (3HGI) enzyme that is used for degrading these types of compounds and also identifies the values of binding energy that compactable with constant values of biological degradation rate. It is noted that binding energy inversely proportional with rate constants and binding energy (R=0.951), as the binding energy with enzyme are increased, the degradation rate are decreased.The study observes that binding energy values were ranging between ([-5.051] - [-7.12] Kcal/mol) whereas values of root mean squared deviation (RMSD) were ranging between (1.12-1.71A°) by which accurate results have been confirmed depending on previous studies. The study also determines the amino acids that surround the compounds which are usually blinded by the hydrogen bond or hydrophobic interactions types π-π.Finally, the study obtains a three – dimensional shape of compound's binding with enzyme of its more stable shape. Also obtains the shapes of distribution of the electronic cloud on the compound and amino acids that are surrounding them in which getting locations around the studied compound's molecule depending on their features of an amino acid (acidity – basic – hydrophobic). MOE (Molecular Operating Environment) is used for this step of calculation.

Engineering Hyperthermophilic Archaeon Pyrococcus furiosus to Overproduce Its Cytoplasmic [NiFe]-Hydrogenase

The cytoplasmic hydrogenase (SHI) of the hyperthermophilic archaeon Pyrococcus furiosus is an NADP(H)-dependent heterotetrameric enzyme that contains a nickel-iron catalytic site, flavin, and six iron-sulfur clusters. It has potential utility in a range of bioenergy systems in vitro, but a major obstacle in its use is generating sufficient amounts. We have engineered P. furiosus to overproduce SHI utilizing a recently developed genetic system. In the overexpression (OE-SHI) strain, transcription of the four-gene SHI operon was under the control of a strong constitutive promoter, and a Strep-tag II was added to the N terminus of one subunit. OE-SHI and wild-type P. furiosus strains had similar rates of growth and H(2) production on maltose. Strain OE-SHI had a 20-fold higher transcription of the polycistronic hydrogenase mRNA encoding SHI, and the specific activity of the cytoplasmic hydrogenase was ∼10-fold higher when compared with the wild-type strain, although the expression levels of genes encoding processing and maturation of SHI were the same in both strains. Overexpressed SHI was purified by a single affinity chromatography step using the Strep-tag II, and it and the native form had comparable activities and physical properties. Based on protein yield per gram of cells (wet weight), the OE-SHI strain yields a 100-fold higher amount of hydrogenase when compared with the highest homologous [NiFe]-hydrogenase system previously reported (from Synechocystis). This new P. furiosus system will allow further engineering of SHI and provide hydrogenase for efficient in vitro biohydrogen production.