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51.
52.
Kuan-Chieh Ching Elaine J. Chin Mario Wibowo Zann Y. Tan Lay-Kien Yang Deborah C. Seow Chung-Yan Leong Veronica W. Ng Siew-Bee Ng Yoganathan Kanagasundaram 《Molecules (Basel, Switzerland)》2023,28(1)
Thiopeptides are macrocyclic natural products with potent bioactivity. Nine new natural thiopeptides (1–9) were obtained from a Nonomuraea jiangxiensis isolated from a terrestrial soil sample collected in Singapore. Even though some of these compounds were previously synthesized or isolated from engineered strains, herein we report the unprecedented isolation of these thiopeptides from a native Nonomuraea jiangxiensis. A comparison with the literature and a detailed analysis of the NMR and HRMS of compounds 1–9 was conducted to assign their chemical structures. The structures of all new compounds were highly related to the thiopeptide antibiotics GE2270, with variations in the substituents on the thiazole and amino acid moieties. Thiopeptides 1–9 exhibited a potent antimicrobial activity against the Gram-positive bacteria, Staphylococcus aureus with MIC90 values ranging from 2 µM to 11 µM. In addition, all compounds were investigated for their cytotoxicity against the human cancer cell line A549, none of the compounds were cytotoxic. 相似文献
53.
A model for predicting the effective thermal conductivity of nanofluids is proposed. It has been documented that the interfacial layer at the solid (particle)/liquid interface and particle size is one of the major mechanisms for enhancing the thermal conductivity of nanofluids. Comparing with other classical models, the proposed model takes into account some additional effects including volume fraction, thickness, thermal conductivity of the interfacial layer and particle size. The proposed model is found to be better than the existing models since the predicted effective thermal conductivity of different types of nanofluids are closer to the experimental results. 相似文献
54.
Partial purification of acid pyrophosphatase activity from dried red kidney beans was achieved. The crude enzyme was found
to adhere to plastic and was very unstable. These problems were solved by extraction with low pH and high-ionic-strength buffers.
This extraction procedure separated acid pyrophosphatase activity into three parts. One of these activities appears to correspond
to the purple phosphatase isolated by other workers (1—3). The other two fractions showed both general phosphomonoesterase
and pyrophosphatase activity, but were most active with pyrophosphate and were used for further characterization. The pH optimum
for the enzyme was approx 5.5-6.0 with pyrophosphatase, and it exhibited substrate inhibition with pyrophosphate and ATP at
low pH. The partially purified acid pyrophosphatase was estimated to be a dimer of approx 98 kDa (mol wt estimated by gel
filtration on Sephacryl S-200) with no detectable carbohydrate or iron content. Of the cations tested for their effect on
pyrophosphatase activity, iron was the most inhibitory, followed by magnesium and zinc. 相似文献
55.
Boon Leong Lan 《International Journal of Theoretical Physics》2008,47(10):2686-2689
Contrary to conventional view, it is shown that, for an ensemble of either single-particle systems or multi-particle systems,
the realistic interpretation of a mathematical superposition of states that mathematically describes the ensemble does not
imply that the ensemble is a mixture. Therefore it cannot be argued, as is conventionally done, that the realistic interpretation
is wrong on the basis that some predictions derived from the mixture are different from the corresponding predictions derived
from the mathematical superposition of states. 相似文献
56.
LetLbe a Moufang loop of odd orderpαqα11···qnαnwherepandqiare primes with 3 ≤ p < q1 < ··· < qnand αi ≤ 2. In this paper, we prove thatLis a group ifpandqiare primes with 3 ≤ p < q1 < ··· < qn: (i) α ≤ 3, or (ii) α ≤ 4,p ≥ 5. 相似文献
57.
58.
The iridium complex [Cp1IrCl2]2 is a good catalyst for the directed oxidative coupling of arenes with alkenes; a wide range of carbonyl functionalities (NHCOR, CONH2 and COR) can be employed as the directing group. 相似文献
59.
We demonstrate mass-producible, mobile, self-loading microcontainers that can be used to encapsulate both non-living and living objects, thus forming three-dimensionally patterned, mobile microwells. 相似文献
60.
The interaction between the osmium clusters [Os3(CO)12], [Os3(CO)10(mu-H)2], [Os3(CO)10(mu-H)(mu-OH)], and a series containing a free functional group, viz., [Os3(CO)10(mu-H)(mu-S--EH)] (where -- =alkylwedge chain or an aromatic ring, E=COO, S or O), with SiO2, ZnO and In2O3, was examined by ToF-SIMS and IR spectroscopy. While the interaction with the silica surface is mostly via an O atom or the functional group, the interaction with the ZnO and In2O3 surfaces is more complex. 相似文献