Expression,purification and functional characterization of a recombinant scorpion venom peptide BmTXKbeta

BmTXKbeta, a scorpion toxin isolated from the Chinese scorpion Buthus martensii Karsch (BmK), was expressed as a GST fusion protein in BL21 (DE3) strain. The recombinant GST-BmTXKbeta protein was purified by affinity chromatography. When treated with enterokinase, the GST-BmTXKbeta fusion protein released an approximate 6.5kDa protein which was the expected size for correctly processed. About 2mg purified recombinant BmTXKbeta protein (rBmTXKbeta) was produced from 1l bacterial culture, using this expression and purification system. The function of rBmTXKbeta was studied on the rabbit atrial myocyte by whole-cell patch clamp technique. The results showed that rBmTXKbeta inhibited the transient outward current (I(to)) of rabbit atrial myocyte with recovery after washout and the inhibition was concentration-dependent. The rBmTXKbeta prolonged the action potential duration of rabbit atrial myocyte in a concentration-dependent manner, whereas it did not affect the action potential amplitude.     

Replication checkpoint protein Mrc1 is regulated by Rad3 and Tel1 in fission yeast

Fission yeast Mrc1 (mediator of replication checkpoint 1) is an adaptor checkpoint protein required for Rad3-dependent activation of the checkpoint kinase Cds1 in response to arrest of replication forks. Here we report studies on the regulation of Mrc1 by phosphorylation. Replication arrest induced by hydroxyurea (HU) induces Mrc1 phosphorylation that is detected by a change in Mrc1 electrophoretic mobility. Phosphorylation is maintained in cds1Delta, rad3Delta, and tel1Delta single mutants but eliminated in a rad3Delta tel1Delta double mutant. Mrc1 has two clusters of S/TQ motifs that are potential Rad3/Tel1 phosphorylation sites. Mutation of six S/TQ motifs in these two clusters strongly impairs Mrc1 phosphorylation. Two motifs located at S604 and T645 are vital for HU resistance. The T645A mutation strongly impairs a Cds1-Mrc1 yeast two-hybrid interaction that is dependent on a functional forkhead-associated (FHA) domain in Cds1, indicating that phosphorylation of T645 mediates Mrc1's association with Cds1. Consistent with this model, the T645 region of Mrc1 effectively substitutes for the T11 region of Cds1 that is thought to be phosphorylated by Rad3 and to mediate FHA-dependent oligomerization of Cds1. The S/TQ cluster that includes S604 is needed for Mrc1's increased association with chromatin in replication-arrested cells. These data indicate that Rad3 and Tel1 regulate Mrc1 through differential phosphorylation to control Cds1.     

Potential role for ADAM15 in pathological neovascularization in mice

ADAM15 (named for a disintegrin and metalloprotease 15, metargidin) is a membrane-anchored glycoprotein that has been implicated in cell-cell or cell-matrix interactions and in the proteolysis of molecules on the cell surface or extracellular matrix. To characterize the potential roles of ADAM15 during development and in adult mice, we analyzed its expression pattern by mRNA in situ hybridization and generated mice carrying a targeted deletion of ADAM15 (adam15(-/-) mice). A high level of expression of ADAM15 was found in vascular cells, the endocardium, hypertrophic cells in developing bone, and specific areas of the hippocampus and cerebellum. However, despite the pronounced expression of ADAM15 in these tissues, no major developmental defects or pathological phenotypes were evident in adam15(-/-) mice. The elevated levels of ADAM15 in endothelial cells prompted an evaluation of its role in neovascularization. In a mouse model for retinopathy of prematurity, adam15(-/-) mice had a major reduction in neovascularization compared to wild-type controls. Furthermore, the size of tumors resulting from implanted B16F0 mouse melanoma cells was significantly smaller in adam15(-/-) mice than in wild-type controls. Since ADAM15 does not appear to be required for developmental angiogenesis or for adult homeostasis, it may represent a novel target for the design of inhibitors of pathological neovascularization.     

A simple parameter relating sequences with folding rates of small alpha helical proteins

It is found that the helix parameter (HP), which favors clustering of non-polar residues, is linearly correlated with the logarithms of rate constants of folding of small two-state alpha-helical proteins. The definition is HP = N(H)(-1) sigma [f(i)+ (f(i-1)+f(i+1))/2], where f(i)=1 or -1, if the i'th residue is hydrophobic or hydrophilic, respectively, N(H) is the number of hydrophobic residues and the summation is taken over the hydrophobic residues.     

Synthesis of radiolabeled biphenylsulfonamide matrix metalloproteinase inhibitors as new potential PET cancer imaging agents

Novel matrix metalloproteinase (MMP) inhibitor radiotracers, (S)-3-methyl-2-(2',3',4'-methoxybiphenyl-4-sulfonylamino)-butyric acid [(11)C]methyl ester (1a-c), (S)-3-methyl-2-(2',3',4'-fluorobiphenyl-4-sulfonylamino)-butyric acid [(11)C]methyl ester (1d-f), and (S)-3-methyl-2-(4'-nitrobiphenyl-4-sulfonylamino)-butyric acid [(11)C]methyl ester (1g), a series of substituted biphenylsulfonamide derivatives, have been synthesized for evaluation as new potential positron emission tomography (PET) cancer imaging agents.     

Acupuncture effects on reflex responses to mental stress in humans

In animal studies, acupuncture has been shown to be sympathoinhibitory, but it is unknown if acupuncture is sympathoinhibitory in humans. Nineteen healthy volunteers underwent mental stress testing pre- and postacupuncture. Muscle sympathetic nerve activity (MSNA), blood pressure, and heart rate during mental stress were compared pre- and postacupuncture. Control acupuncture consisted of acupuncture at nonacupoints and "no-needle" acupuncture. Acupuncture had no effect on resting MSNA, blood pressure, or heart rate. After real acupuncture, the increase in mean arterial pressure (pre- vs. postacupuncture 4.5 vs. 1.7 mmHg, P < 0.001), but not MSNA or heart rate, was blunted during mental stress. Similarly, following nonacupoint acupuncture, the increase in mean arterial pressure was blunted during mental stress (5.4 vs. 2.9 mmHg, P < 0.0003). No-needle acupuncture had no effect on these variables. In conclusion, acupuncture at traditional acupoints, nonacupoints, and no-needle acupuncture does not modulate baseline MSNA or MSNA responses to mental stress in normal humans. Acupuncture significantly attenuates the increase in blood pressure during mental stress. Needling nonacupoints, but not "no-needle" acupuncture, have a similar effect on blood pressure.     

疏花毛萼香茶菜中一新的对映-贝壳杉烷型二萜

从疏花毛萼香茶菜（Ｉｓｏｄｏｎ ｅｒｉｏｃａｌｙｘ ｖａｒ．ｌａｘｉｆｌｏｒａ）叶中分离得到一新的对映－贝壳杉烷型二萜,命名为疏花丁素（１）,通过波谱方法鉴定了它的结构。此外,还分离得到６个已知对映－贝壳杉烷型二萜化合物：疏花甲素（２）,毛萼晶Ａ－Ｃ（３－５）和Ｑ（６）,毛萼乙素（７）,以及ｃｉｒｓｉｍａｒｉｔｉｎ（８）和２α－羟基乌索酸（９）。