Identification of a Reliable DFT Calculation Method to Predict the Ground-and Excited-State Properties of Nickel(Ⅱ) Complexes with Porphyrin in Crude Oil

Metalloporphyrins have devastating effects on the deep processing and efficient utilization of petroleum resources. Various porphyrins are derived from porphin by substitution at the β, meso, or both positions. Herein, we focus on the interaction between nickel(Ⅱ) and the porphyrin skeleton. Five different density functionals were selected for determining a reliable approach to simulate porphyrin-nickel(Ⅱ) complexes. At D4h symmetry, the 10b1g, 15a1g, 4e1g and 9b2g were dominated by the 3d character of nickel. Compared with pure density functional, the hybrid functional gave larger highest occupied molecular orbital(HOMO) and lowest unoccupied molecular orbital(LUMO) gap, and the higher HOMO-LUMO gap also corresponded to a higher excitation energy. The characteristic Soret and Q bands modeled by timedependent density functional theory(TDDFT) calculations matched well with experimental results, and the absorption was discussed in detail with natural transition orbitals(NTO) analysis. Furthermore, the binding character of nickel(Ⅱ) with various substituted porphyrins were calculated at perdew-burke-ernzerhof(PBE) level, showed that the geometry and complexation behavior of porphyrin-nickel(Ⅱ) complexes could be significantly tuned by different substituents. The symmetry of the complex was reduced and the skeleton ring get distortion when introducing different substituents. Compared with ETIO porphyrin, the introduction of phenyl on the β position can expand the conjugated system and promote the covalent character of Ni-N bond.

Adsorption/reaction energetics measured by microcalorimetry and correlated with reactivity on supported catalysts: A review

The formations and transformations of the chemical bonds of reactants and intermediates on cata- lyst surfaces occur in conjunction with the evolution of heat during catalytic reactions. Measure- ment of this evolved heat is helpful in terms of understanding the nature of the interactions be- tween the catalyst and the adsorbed species, and provides insights into the reactivity of the catalyst. Although various techniques have previously been applied to assessments of evolved heat, direct measurements using a Tian-Calvet microcalorimeter are currently the most reliable method for this purpose. In this review, we summarize the relationship between the adsorption/reaction energetics determined by microcalorimetry and the reactivities of supported catalysts, and examine the im- portant role of microcalorimetry in understanding catalytic performance from the energetic point of view.

Rapid characterization of the binding property of HtrA2/Omi PDZ domain by validation screening of PDZ ligand library

HtrA2/Omi is a mammalian mitochondrial serine protease, and was found to have dual roles in mam- malian cells, not only acting as an apoptosis-inducing protein but also maintaining mitochondrial ho- meostasis. PDZ domain is one of the most important protein-protein interaction modules and is in- volved in a variety of important cellular functions, such as signal transduction, degradation of proteins, and formation of cytoskeleton. Recently, it was reported that the PDZ domain of HtrA2/Omi might regulate proteolytic activity through its interactions with ligand proteins. In this study, we rapidly characterized the binding properties of HtrA2/Omi PDZ domain by validation screening of the PDZ ligand library with yeast two-hybrid approach. Then, we predicted its novel ligand proteins in human proteome and reconfirmed them in the yeast two-hybrid system. Finally, we analyzed the smallest networks bordered by the shortest path length between the protein pairs of novel interactions to evaluate the confidence of the identified interactions. The results revealed some novel binding proper- ties of HtrA2/Omi PDZ domain. Besides the reported Class II PDZ motif, it also binds to Class I and Class III motifs, and exhibits restricted variability at P?3, which means that the P?3 residue is selected according to the composition of the last three residues. Seven novel ligand proteins of HtrA2/Omi PDZ domain were discovered, providing significant clues for further clarifying the roles of HtrA2/Omi. Moreover, this study proves the high efficiency and practicability of the newly developed validation screening of candidate ligand library method for binding property characterization of peptide-binding domains.