Thiazolidine-2-carboxylate derivatives formed from glyoxylate and L-cysteine or L-cysteinylglycine as possible physiological substrates for D-aspartate oxidase

Adducts of glyoxylate with L-cysteine or L-cysteinylglycine were found to be excellent substrates at low concentrations for beef kidney D-aspartate oxidase. Evidence is presented that cis-thiazolidine-2,4-dicarboxylate and its glycine amide are the actual substrates, and that both are converted in the enzymic reaction to 4-substituted thiazoline-2-carboxylates. The results imply that these thiazolidine derivatives are the likely physiological reactants for mammalian D-aspartate oxidase.     

Regulation of eumelanin/pheomelanin synthesis and visible pigmentation in melanocytes by ligands of the melanocortin 1 receptor

The production of melanin in the hair and skin is tightly regulated by the melanocortin 1 receptor (MC1R) whose activation is controlled by two secreted ligands, alpha-melanocyte stimulating hormone (alphaMSH) and agouti signal protein (ASP). As melanin is extremely stable, lasting years in biological tissues, the mechanism underlying the relatively rapid decrease in visible pigmentation elicited by ASP is of obvious interest. In this study, the effects of ASP and alphaMSH on the regulation of melanin synthesis and on visible pigmentation were assessed in normal murine melanocytes and were compared with the quick depigmenting effect of the tyrosinase inhibitor, phenylthiourea (PTU). alphaMSH increased pheomelanin levels prior to increasing eumelanin content over 4 days of treatment. Conversely, ASP switched off the pigment synthesis pathway, reducing eu- and pheo-melanin synthesis within 1 day of treatment that was proportional to the decrease in tyrosinase protein level and activity. These results demonstrate that the visible depigmentation of melanocytes induced by ASP does not require the degradation of existing melanin but rather is due to the dilution of existing melanin by melanocyte turnover, which emphasizes the importance of pigment distribution to visible color.     

Predicting conformational switches in proteins.

We describe a new computational technique to predict conformationally switching elements in proteins from their amino acid sequences. The method, called ASP (Ambivalent Structure Predictor), analyzes results from a secondary structure prediction algorithm to identify regions of conformational ambivalence. ASP identifies ambivalent regions in 16 test protein sequences for which function involves substantial backbone rearrangements. In the test set, all sites previously described as conformational switches are correctly predicted to be structurally ambivalent regions. No such regions are predicted in three negative control protein sequences. ASP may be useful as a guide for experimental studies on protein function and motion in the absence of detailed three-dimensional structural data.     

Structural evidence for variable oligomerization of the N-terminal domain of cyclase-associated protein (CAP)

Cyclase-associated protein (CAP) is a highly conserved and widely distributed protein that links the nutritional response signaling to cytoskeleton remodeling. In yeast, CAP is a component of the adenylyl cyclase complex and helps to activate the Ras-mediated catalytic cycle of the cyclase. While the N-terminal domain of CAP (N-CAP) provides a binding site for adenylyl cyclase, the C-terminal domain (C-CAP) possesses actin binding activity. Our attempts to crystallize full-length recombinant CAP from Dictyostelium discoideum resulted in growth of orthorhombic crystals containing only the N-terminal domain (residues 42-227) due to auto-proteolytic cleavage. The structure was solved by molecular replacement with data at 2.2 A resolution. The present crystal structure allows the characterization of a head-to-tail N-CAP dimer in the asymmetric unit and a crystallographic side-to-side dimer. Comparison with previously published structures of N-CAP reveals variable modes of dimerization of this domain, but the presence of a common interface for the side-to-side dimer.     

Discovery and structural characterization of peficitinib (ASP015K) as a novel and potent JAK inhibitor

Janus kinases (JAKs) are considered promising targets for the treatment of autoimmune diseases including rheumatoid arthritis (RA) due to their important role in multiple cytokine receptor signaling pathways. Recently, several JAK inhibitors have been developed for the treatment of RA. Here, we describe the identification of the novel orally bioavailable JAK inhibitor 18, peficitinib (also known as ASP015K), which showed moderate selectivity for JAK3 over JAK1, JAK2, and TYK2 in enzyme assays. Chemical modification at the C4-position of lead compound 5 led to a large increase in JAK inhibitory activity and metabolic stability in liver microsomes. Furthermore, we determined the crystal structures of JAK1, JAK2, JAK3, and TYK2 in a complex with peficitinib, and revealed that the 1H-pyrrolo[2,3–b]pyridine-5-carboxamide scaffold of peficitinib forms triple hydrogen bonds with the hinge region. Interestingly, the binding modes of peficitinib in the ATP-binding pockets differed among JAK1, JAK2, JAK3, and TYK2. WaterMap analysis of the crystal structures suggests that unfavorable water molecules are the likely reason for the difference in orientation of the 1H-pyrrolo[2,3-b]pyridine-5-carboxamide scaffold to the hinge region among JAKs.     

Association of the common FTO-rs9939609 polymorphism with type 2 diabetes,independent of obesity-related traits in a Vietnamese population

Type 2 diabetes (T2D) is a complex disorder resulting from both genetic and environmental factors in its pathogenesis. A case − control study was designed with subjects recruited from a general population to investigate whether the association between T2D and the common T > A polymorphism (rs9939609) in fat mass and obesity associated (FTO) gene is mediated by obesity-related measurements, considering the contribution of socio-economic status and lifestyle factors. The significant association between the FTO rs9939609 polymorphism and T2D was first observed in the model unadjusted (OR per A allele = 1.61, 95% CI = 1.06–2.44, P = 0.024). It remained consistently replicated in the final model after adjustments for sex, age, systolic blood pressure, socio-economic status, lifestyle factors, and obesity-related measurements (body mass index, waist–hip ratio, body fat percentage, and body adiposity index), showing an increased T2D risk with an additive effect of the alleles (ORs per A allele = 1.80–1.92, 95% CI = 1.09–3.19, P < 0.05). The FTO-rs9939609 polymorphism, systolic blood pressure, and waist–hip ratio were the most significant independent predictors for T2D, in which the power of the adjusted prediction model was 0.769. In conclusion, the study suggested that the FTO-rs9939609 polymorphism was significantly associated with the increased risk of T2D, independent of obesity-related measurements in a Vietnamese population.     

乙酰水杨酸处理对猕猴桃果实成熟衰老的影响及其作用机理

以不同后熟软化阶段猕猴桃果肉组织圆片为材料 ,在 2 0℃下用 1.0mmol L(pH 3.5 )的乙酰水杨酸(ASP)分别处理 4、12和 2 4h后 ,分析其对果实成熟衰老相关因子的影响。结果表明 ,随着果实成熟衰老 ,内源游离SA下降 ,LOX活性增加 ,超氧自由基 (O- ·2 )生成速率增加 ,乙烯释放量加大 ;ASP处理促使组织内源SA水平的增加 ,降低了O- ·2 生成速率 ,抑制了LOX、ACC合成酶和ACC氧化酶的活性以及乙烯的生成。推测ASP可能作为O- ·2 等自由基清除剂 ,通过负反馈调控LOX途径 ,延缓果实的成熟衰老     

阿司匹林和复方新诺明对大豆种子萌发及活力的影响

 以大豆(Glycine max)种子为材料,浓度的阿斯匹林和复方新诺明水溶液,在(20±1)℃条件下分种24h和12h, 测定大豆种子萌发过程中的各项生理生化指标以及萌发后的各形态指标实验结果表明：阿斯匹林和复方新诺明水溶液浸种都能有效地提高大豆种子的发芽率和活力指数,还能促进大豆根系的生长。其中以62.5mg·L-1的阿斯匹林和0.5mg·L-1的复方新诺明处理后的效果最为显著。阿斯匹林浸种能使大豆萌芽的相对电导率显著降低,使活性氧清除酶的活性有所提高。复方新诺明浸种则使大豆萌芽的蛋白质含量以及氨基酸总量都有显著的提高。     

Species composition and toxicity of the genus Pseudo-nitzschia in Taiwan Strait,including P. chiniana sp. nov. and P. qiana sp. nov.

In a field survey in the Taiwan Strait during April 2016, the species composition and the domoic acid production of the diatom genus Pseudo-nitzschia were investigated. A total of 80 strains of Pseudo-nitzschia were established, and species identification was determined based on a combination of morphological and molecular data. Fourteen taxa were recognized, i.e., P. americana, P. brasiliana, P. calliantha, P. cuspidata, P. galaxiae, P. lundholmiae, P. multiseries, P. multistriata, P. pseudodelicatissima, P. pungens var. aveirensis, P. pungenus var. pungens and P. sabit, as well as two novel species P. chiniana C.X. Huang & Yang Li and P. qiana C.X. Huang & Yang Li. Morphologically, P. chiniana is characterized by striae comprising one or two rows of poroids, and valve ends that are normally dominated by two rows of poroids within each stria. Whereas P. qiana is unique by having a narrow valve width (1.3–1.5 μm) and sharply pointed valve ends. Both taxa constitute their own monophyletic lineage in the phylogenetic analyses inferred from LSU and ITS2 rDNA, and are well differentiated from other Pseudo-nitzschia species. Pseudo-nitzschia chiniana forms a group with P. abrensis and P. batesiana in LSU and ITS trees, whereas P. qiana is sister to P. lineola. When comparing ITS2 secondary structure, five CBCs and seven HCBCs are recognized between P. chiniana and P. abrensis, and four CBCs and ten HCBCs between P. chiniana and P. batesiana. Two CBCs and eight HCBCs are found between P. qiana with P. lineola. The ability of the strains to produce domoic acid was assessed, including a potential toxin induction by the presence of brine shrimps. Results revealed production of domoic acid in six strains belonging to three species. Without presence of brine shrimps, cellular DA (pDA) was detected in four P. multiseries strains (1.6 ± 0.3, 26.6 ± 2.7, 68.3 ± 4.2 and 56.9 ± 4.7 fg cell⁻¹, separately), one strain of P. pseudodelicatissima (0.8 ± 0.2 fg cell⁻¹) and one strain of P. lundholmiae (2.5 ± 0.4 fg cell⁻¹). In the presence of brine shrimps, pDA contents increased significantly (p < 0.05) in P. lundholmiae (strain MC4218) and P. multiseries (strain MC4177), from 2.5 ± 0.4 to 8.9 ± 0.7 and 1.6 ± 0.3 to 37.2 ± 2.5 fg cell⁻¹ respectively.     

Design and characterization of electrochromic membrane probes

Electrochromic membrane probes display a spectroscopic response to membrane poteintial by a direct electronic mechanism. This allows such probes to be designed a priori via quantum-chemical techniques. The detailed behavior of potentiometric optical probes can be elucidated with an apparatus based on phase-sensitive detection from a hemispherical lipid bilayer; several different types of response spectra can be obtained with this apparatus allowing distinction between the electrochromic mechanism and the more common molecular-motion based mechanisms. The development of ‘fast’ potentiometri dyes has now reached a stage where practical and exciting applications are rapidly appearing. It is anticipated that the emergence of a complementary set of electrochromic probes will lead to new applications; in particular, it may be possible to elucidate the molecular events which underlie biological or physiological phenomena.