Signal Space Diversity Techniques with Fast Decoding Based on MDS Codes

Yue Shang,Dong Wang,Xiang-Gen Xia IEEE 2010 IEEE TRANSACTIONS ON COMMUNICATIONS Vol.58 No.9

<P>In wireless communication systems, signal space diversity techniques are usually adopted to combat channel fading by exploiting time diversity, frequency diversity, spatial diversity or a combination of them. Most existing schemes to achieve signal space diversity are based on linear constellation spreading. In this paper, we propose a novel nonlinear signal space diversity technique based on maximum distance separable (MDS) codes. The new technique provides a design flexibility for almost any number of diversity channels and desired diversity orders. We also propose a simple and suboptimal diversity channel selection (DCS) decoding for our new scheme. DCS decoding can greatly reduce the decoding complexity at a cost of marginal performance loss relative to the optimal detection while keeping the diversity order. Simulation results show that with the same throughput but a lower decoding and implementation complexity, our scheme can have superior performance than the optimal linear spreading schemes over either independent fading or additive white Gaussian noise (AWGN) channels.</P>

The inhibitory effect of pyrogallol on tyrosinase activity and structure: Integration study of inhibition kinetics with molecular dynamics simulation

Xiong, Shang-Ling,Lim, Gyu Tae,Yin, Shang-Jun,Lee, Jinhyuk,Si, Yue-Xiu,Yang, Jun-Mo,Park, Yong-Doo,Qian, Guo-Ying Elsevier 2019 INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES Vol.121 No.-

<P><B>Abstract</B></P> <P>Pyrogallol is naturally found in aquatic plant and has been proposed as a substrate of tyrosinase. In this study, we evaluated the dual effect of pyrogallol on tyrosinase as an inhibitor in the presence of L‑DOPA simultaneously via integrating methods of enzyme kinetics and computational molecular dynamics (MD) simulations. Pyrogallol was found to be a reversible inhibitor of tyrosinase in the presence of L‑DOPA and its induced mechanism was the parabolic non-competitive inhibition type (<I>IC</I> <SUB>50</SUB> = 0.772 ± 0.003 mM and <I>K</I> <SUB>i</SUB> = 0.529 ± 0.022 mM). Kinetic measurements by real-time interval assay showed that pyrogallol induced rapid inactivation process composing with slight activations at the low dose. Spectrofluorimetry studies showed that pyrogallol mainly induced regional changes in the active site of tyrosinase accompanying with hydrophobic disruption at high dose. The computational MD simulations further revealed that pyrogallol could interact with several residues near the tyrosinase active site pocket such as HIS61, HIS85, HIS259, ASN260, HIS263, VAL283, and ALA296. Our study provides insight into the mechanism by which hydroxyl group composing pyrogallol inhibit tyrosinase and pyrogallol is a potential natural anti-pigmentation agent.</P>

The effect of thiobarbituric acid on tyrosinase: inhibition kinetics and computational simulation.

Yin, Shang-Jun,Si, Yue-Xiu,Wang, Zhi-Jiang,Wang, Su-Fang,Oh, Sangho,Lee, Sanghyuk,Sim, Seon-Mi,Yang, Jun-Mo,Qian, Guo-Ying,Lee, Jinhyuk,Park, Yong-Doo Adenine Press 2011 Journal of biomolecular structure & dynamics Vol.29 No.3

<P>Tyrosinase plays various roles in organisms and much research has focused on the regulation of tyrosinase activity. We studied the inhibitory effect of thiobarbituric acid (TBA) on tyrosinase. Our kinetic study showed that TBA inhibited tyrosinase in a reversible noncompetitive manner (K(i) 5 14.0 ± 8.5 mM and IC?????? 5 8.0 ± 1.0 mM). Intrinsic and ANS-binding fluorescences studies were also performed to gain more information regarding the binding mechanism. The results showed that no tertiary structural changes were obviously observed. For further insight, we predicted the 3D structure of tyrosinase and simulated the docking between tyrosinase and TBA. The docking simulation was successful with significant scores (binding energy for AutoDock4: -5.52 kcal/mol) and suggested that TBA was located in the active site. The 11 ns molecular dynamics simulation convinced that the four HIS residues (residue numbers: 57, 90, 250, and 282) were commonly responsible for the interaction with TBA. Our results provide a new inhibition strategy that works using an antioxidant rather than targeting the copper ions within the tyrosinase active site.</P>

The Inhibitory Effects of Cu(2+) on Exopalaemon carinicauda Arginine Kinase via Inhibition Kinetics and Molecular Dynamics Simulations.

Si, Yue-Xiu,Lee, Jinhyuk,Yin, Shang-Jun,Gu, Xiao-Xu,Park, Yong-Doo,Qian, Guo-Ying Humana Press 2015 Applied biochemistry and biotechnology Vol.176 No.4

<P>We studied the Cu2+-mediated inhibition and aggregation of Exopalaemon carinicauda arginine kinase ( ECAK). We found that Cu2+ significantly inactivated ECAK activity and double-reciprocal kinetics demonstrated that Cu2+ induced noncompetitive inhibition of arginine and ATP ( IC50=2.27 +/- 0.16 mu M; K-i for arginine=13.53 +/- 3.76; K-i for ATP=4.02 +/- 0.56). Spectrofluorometry results showed that Cu2+ induced ECAK tertiary structural changes including the exposure of hydrophobic surfaces that directly induced ECAK aggregation. The addition of osmolytes such as glycine and proline successfully blocked ECAK aggregation induced by Cu2+ and recovered ECAK activity. We built a 3D structure for ECAK using the ECAK ORF gene sequence. Molecular dynamics ( MD) and docking simulations between ECAK and Cu2+ were conducted to elucidate the binding mechanisms. The results showed that Cu2+ blocked the entrance to the ATP active site; these results are consistent with the experimental result that Cu2+ induced ECAK inactivation. Since arginine kinase ( AK) plays an important role in cellular energy metabolism in invertebrates, our study can provide new information about the effect of Cu2+ on ECAK enzymatic function and unfolding, including aggregation, and the protective effects of osmolytes on ECAK folding to better understand the role of the invertebrate ECAK metabolic enzyme in marine environments.</P>

Family Hilarimorphidae (Diptera) newly recorded from China with descriptions of three new species

Liu Yue,Gao Shang,Yang Ding 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.2

The family Hilarimorphidae is reported from China for the first time. Three new species are described and illustrated: Hilarimorpha dingae sp. nov., Hilarimorpha elongata sp. nov. and Hilarimorpha tibetensis sp. nov. A key to species of Hilarimorpha from Asia and a checklist of world species of Hilarimorphidae are provided.

Metabolic responses and arginine kinase expression of juvenile cuttlefish (<i>Sepia pharaonis</i>) under salinity stress

Yin, Shang-Jun,Zhang, Linmeng,Zhang, Lili,Wan, Jiaxin,Song, Wei,Jiang, Xiamin,Park, Yong-Doo,Si, Yue-Xiu Elsevier 2018 INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES Vol.113 No.-

<P><B>Abstract</B></P> <P>The pharaoh cuttlefish <I>Sepia pharaonis</I> is particularly sensitive to environmental changes in its breeding environment. The breeding of <I>S</I>. <I>pharaonis</I> larvae was carried out in different salinities for 48h, and the changes in survival rate, histological structure, energy metabolism, and anti-oxidative stress parameters were investigated and correlated with arginine kinase (AK) expression changes in muscle and liver tissues. The suitable salinity for larvae cultivation ranged from 24 to 30‰, and the survival rate showed a significant decline at 21‰ salinity. Histological observations of muscle and liver showed that changes in salinity and osmotic pressure had an adverse effect on tissue structure. Measurements of glycogen and lactic acid levels suggested that <I>S</I>. <I>pharaonis</I> could dynamically adjust energy metabolism to provide additional energy under unsuitable salinity. The protein levels and enzyme activities of AK in muscle significantly increased at 21‰ salinity. The results were consistent with prompt replenishment of phosphoarginine stores during salinity stress to maintain a dynamic ATP balance, suggesting that AK plays an important role in the regulation of energy metabolism. This study provides insight into metabolic changes during salinity stress and sheds light on the functional role of AK in <I>S</I>. <I>pharaonis</I>.</P>

Brittle fracture and plastic creep of the completely decomposed granite presented in CT

Yanjun Shang,Zhongqi Yue,박형동,현창욱 한국자원공학회 2015 Geosystem engineering Vol.18 No.6

Completely decomposed granite (CDG) with different structures shows different patterns in deformation and failure as brittle fracture or as plastic creep in triaxial test. It is necessary to monitor and to compare the fabric changes due to stress in real time during test. By means of the computerized tomography (CT) technique for monitoring deformation and failure of soils in real time without suspending the mechanical test and disturbing samples, a newly designed triaxial test machine was used to test CDG from Hong Kong in a procedure of saturation, consolidation and undrained condition. It was found that CT data (images and values) depicts the failure patterns as brittle fracture or as plastic creep at 3-D in real time. The results were concordant with stress–strain curves and observation of the appearance of samples before and after tests.

Inhibitory effect of raspberry ketone on α-glucosidase: Docking simulation integrating inhibition kinetics

Xiong, Shang-Ling,Yue, Li-Mei,Lim, Gyu Tae,Yang, Jun-Mo,Lee, Jinhyuk,Park, Yong-Doo Elsevier 2018 INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES Vol.113 No.-

<P><B>Abstract</B></P> <P>Inhibition of α-glucosidase is directly associated with treatment of type 2 diabetes. In this regard, we conducted enzyme kinetics integrated with computational docking simulation to assess the inhibitory effect of raspberry ketone (RK) on α-glucosidase. RK bound to the active site of α-glucosidase and interacted with several key residues such as ASP68, TYR71, HIS111, PHE157, PHE158, PHE177, GLN181, ASP214, THR215, ASP349, ASP408, and ARG439, as detected by protein-ligand docking simulation. Subsequently, we confirmed the action of RK on α-glucosidase as the non-competitive type of inhibition in a reversible and rapidly binding manner. The relevant kinetic parameters were <I>IC</I> <SUB>50</SUB> =6.17±0.46mM and <I>K</I> <SUB> <I>i</I> </SUB> =7.939±0.211mM. Regarding the structure-activity relationship, the higher concentration of RK induced slight modulation of the shape of the active site as monitored by hydrophobic exposure. The tertiary conformational change was linked to RK inhibition, and mostly involved regional changes of the active site. Our study provides insight into the functional role of RK due to its structural property of a hydroxyphenyl ring that interacts with the active site of α-glucosidase. We suggest that similar hydroxyphenyl ring compounds targeting the key residues of the active site might be potential α-glucosidase inhibitors.</P>

Mixed-type inhibition of tyrosinase from Agaricus bisporus by terephthalic acid: computational simulations and kinetics.

Yin, Shang-Jun,Si, Yue-Xiu,Chen, Yong-Fu,Qian, Guo-Ying,L?, Zhi-Rong,Oh, Sangho,Lee, Jinhyuk,Lee, Sanghyuk,Yang, Jun-Mo,Lee, Dong-Youn,Park, Yong-Doo Kluwer Academic/Plenum 2011 The Protein Journal Vol.30 No.4

<P>Tyrosinase inhibition studies are needed due to the agricultural and medicinal applications. For probing effective inhibitors of tyrosinase, a combination of computational prediction and enzymatic assay via kinetics were important. We predicted the 3D structure of tyrosinase from Agaricus bisporus, used a docking algorithm to simulate binding between tyrosinase and terephthalic acid (TPA) and studied the reversible inhibition of tyrosinase by TPA. Simulation was successful (binding energies for Autodock4 = -1.54 and Fred2.0 = -3.19 kcal/mol), suggesting that TPA interacts with histidine residues that are known to bind with copper ions at the active site. TPA inhibited tyrosinase in a mixed-type manner with a K ( i ) = 11.01 2.12 mM. Measurements of intrinsic and ANS-binding fluorescences showed that TPA induced no changes in tertiary structure. The present study suggested that the strategy of predicting tyrosinase inhibition based on hydroxyl groups and orientation may prove useful for screening of potential tyrosinase inhibitors.</P>

An integrated study of tyrosinase inhibition by rutin: progress using a computational simulation.

Si, Yue-Xiu,Yin, Shang-Jun,Oh, Sangho,Wang, Zhi-Jiang,Ye, Sen,Yan, Li,Yang, Jun-Mo,Park, Yong-Doo,Lee, Jinhyuk,Qian, Guo-Ying Adenine Press 2012 Journal of biomolecular structure & dynamics Vol.29 No.5

<P>Tyrosinase inhibition studies have recently gained the attention of researchers due to their potential application values. We simulated docking (binding energies for AutoDock Vina: -9.1 kcal/mol) and performed a molecular dynamics simulation to verify docking results between tyrosinase and rutin. The docking results suggest that rutin mostly interacts with histidine residues located in the active site. A 10 ns molecular dynamics simulation showed that one copper ion at the tyrosinase active site was responsible for the interaction with rutin. Kinetic analyses showed that rutin-mediated inactivation followed a first-order reaction and mono- and biphasic rate constants occurred with rutin. The inhibition was a typical competitive type with K(i) = 1.100.25 mM. Measurements of intrinsic and ANS-binding fluorescences showed that rutin showed a relatively strong binding affinity for tyrosinase and one possible binding site that could be a copper was detected accompanying with a hydrophobic exposure of tyrosinase. Cell viability testing with rutin in HaCaT keratinocytes showed that no toxic effects were produced. Taken together, rutin has the potential to be a potent anti-pigment agent. The strategy of predicting tyrosinase inhibition based on hydroxyl group number and computational simulation may prove useful for the screening of potential tyrosinase inhibitors.</P>