A novel enantioselective total synthesis of 20S proteasome inhibitor Salinosporamide A (NPI-0052; 1) is presented. Key features include intramolecular aldol cyclization of 6 to simultaneously generate the three chiral centers of advanced intermediate 5, cyclohexene ring addition using B-2-cyclohexen-1-yl-9-BBN, and inversion of the C-5 stereocenter by oxidation followed by enantioselective enzy...

N-acyl-L-homoserine lactone hydrolase (AHL lactonase) is a dinuclear zinc enzyme responsible for the hydrolytic ring opening of AHLs, disrupting quorum sensing in bacteria. The reaction mechanism is investigated using hybrid density functional theory. A model of the active site is designed on the basis of the X-ray crystal structure, and stationary points along the reaction pathway are optimize...

Figure 1. (A) The b5 ion is generated by collision induced dissociation resulting in formation of the oxazolone ring through attack of the oxygen lone pair on the newly formed terminal carbonyl group. (B) N-terminal nucleophilic attack of the oxazolone ring to form the macrocycle. (C) The resultant macrocyclic intermediate undergoes ring opening to give sequence scrambled b5 ions. N.B. Numberin...

Metallo-β-lactamases (MβL) catalyzing the hydrolytic cleavage of the four-membered β-lactam ring in broad spectrum of antibiotics and therefore inactivating the drug; However, the mechanism of these enzymes is still not well understood. Electronic structure and electronic energy of metallo-β-lactamase active center, two inhibitors of this enzyme including penicillin and cephalexin, and differen...

Asymmetric syntheses of both 1-deoxy-6,8a-di-epi-castanospermine and 1-deoxy-6-epi-castanospermine, polyhydroxylated indolizidine alkaloids that act as selective glycosidase inhibitors, have been accomplished in seven steps. The key feature of our unique syntheses includes the stereoselective introduction of the C-3 and C-4 hydroxyl groups utilizing the aza-Claisen rearrangement-induced ring ex...

In this study, B12N12 Nano ring has been selected because it consist of four 6-side rings and polar bonds B-N which in comparison with non-polar bonds C-C, is more suitable for the study of the absorption of other compounds. So reactivity and stability of Benzene alone and in the presence B12N12 nano ring field checked. To determine the non-bonded interaction energies between Benzene and B12N12...

Photocatalytic H2O2 production by conversion of O2 in aqueous solution is often challenged the use sacrificial agents, separation powdery photocatalysts, solution, and contaminants, low activity photocatalyst. Herein, a membrane covalent furan-benzimidazole-linked polymer (Furan-BILP) with both O- N-containing heterocycles bonded via OCCN reported for first time as photocatalyst to harvest c...

TANGO1 (transport and Golgi organization 1) interacts with CTAGE5 and COPII components Sec23/Sec24 and recruits ERGIC-53 (endoplasmic reticulum [ER]-Golgi intermediate compartment 53)-containing membranes to generate a mega-transport carrier for export of collagens and apolipoproteins from the ER. We now show that TANGO1, at the ER, assembles in a ring that encircles COPII components. The C-ter...

Polycyclic tetramate macrolactams (PTMs) were identified as distinct secondary metabolites of the mangrove-derived Streptomyces xiamenensis 318. Together with three known compounds-ikarugamycin (1), capsimycin (2) and capsimycin B (3)-two new compounds, capsimycin C (4) with trans-diols and capsimycin D (5) with trans-configurations at C-13/C-14, have been identified. The absolute configuration...

In this study, B12N12 Nano ring has been selected because it consist of four 6-side rings and polar bonds B-N which in comparison with non-polar bonds C-C, is more suitable for the study of the absorption of other compounds. So reactivity and stability of Benzene alone and in the presence B12N12 nano ring field checked. To determine the non-bonded interaction energies between Benzene and B12N12...