The protein inhibitor of adenosine 3′,5′-monophosphate-dependent protein kinases the NH2-terminal portion of the peptide chain contains the inhibitory site

The protein inhibitor of adenosine 3′,5′-monophosphate-dependent protein kinases from skeletal muscle was subjected to various chemical and enzymatic treatments in an attempt to delineate the part of the molecule responsible for the interaction with the catalytic subunit of the kinase. Only a small portion of the chain seems to be required since thermolysin and staphylococcal protease digestions do not abolish the inhibitory properties. This inhibitory site must contain the essential arginyl side chain(s), whereas lysyl and carboxylic side chains do not appear to be involved in the interaction with the catalytic subunit.Digestion of the COOH-terminus of the inhibitor by carboxypeptidase Y results in a doubling of the K_i value. On the other hand, an inhibitory pentadecapeptide (K_i = 25 nM), presumably NH₂-terminal in the entire molecule, could be isolated from a staphylococcal protease digest by means of gel filtration followed by ion exchange on phosphocellulose. The purified inhibitory peptide contains two out of the four arginyl residues present in the entire molecule. The remarkable affinity and specificity of the protein kinase inhibitor for the catalytic subunit of adenosine 3′,5′-monophosphate-dependent protein kinases may thus be tentatively explained on the basic of a two-prong attachment of the inhibitor. The NH₂-terminal portion of the chain would bind at the substate binding site, whereas the COOH-terminal part would be held elsewhere.     

槐庶尺蛾性信息素腺体EAG活性成分绝对构型的鉴定(英文)

槐庶尺蛾Semiothisa cinerearia Bremer et Grey （鳞翅目： 尺蛾科）是我国北方国槐Sophora japonica L.上的重要食叶害虫。本研究的主要目的是阐明槐庶尺蛾性信息素成分化学结构的绝对构型, 为在城市地区环境友好地防控槐庶尺蛾的为害提供一种新方法。经与标准品比较气相色谱保留时间和质谱特征离子, 从槐庶尺蛾处女雌蛾（2-3日龄）性信息素腺体溶剂提取物中检测到顺6, 顺9-顺-3, 4-环氧-十七碳二烯烃和顺3, 顺6, 顺9-3, 6, 9-十七碳三烯烃2种成分, 在腺体中以100∶4.8±1.3 （N=12）的比例存在。槐庶尺蛾性信息素腺体提取物进一步经手性毛细管色谱柱（CycloSil-B, 30 m×0.25 mm×0.25 μm 液膜厚）分离, 在优化的程序升温条件下发现腺体成分顺6, 顺9-顺-3, 4-环氧-十七碳二烯烃具有3R, 4S的绝对构型。两种合成的对映异构体混合物顺6, 顺9-3R, 4S-环氧-十七碳二烯烃和顺6, 顺9-3S, 4R-环氧-十七碳二烯烃以1.28∶1的比例加到腺体提取物中, 比例变为1.55∶1。根据这一分析, 腺体成分顺6, 顺9-顺-3, 4-环氧-十七碳二烯烃进一步确认具有3R, 4S的绝对构型。该研究结论将为生产上研发高效的槐庶尺蛾性信息素诱芯奠定坚实的基础。     

Analysis of the effects of cesium ions on potassium channel currents in biological membranes

Cesium ions block potassium channels in biological membranes in a voltage dependent manner. For example, external cesium blocks inward current with little or no effect on outward current. Consequently, it produces a characteristic N-shaped current-voltage relationship. We have modeled this result by single file diffusion of ions in a narrow channel spanning the membrane with a special blocking site in the channel for cesium ions. The model enables us to make detailed comparisons of the effects of cesium on potassium channels in different types of biological membranes.     

Mapping of the seed storage protein locus Sec-2 in rye

The segregation of the 75K gamma secalin locus (Sec-2) in combination with five interchanges (reciprocal translocations) and two marker genes was analyzed. The translocations involved chromosome arms 1RL, 1RS, 2RL, 2RS, 4RL, 5RL, 5RS, 6RL and 6RS. The gene loci were both on 2R, but the arm was not known. Although the Sec-2 locus was expected to be on chromosome 2RS, no linkage between Sec-2 and any of the markers was found. This is concluded to be the result of exceptionally frequent recombination between Sec-2 and the break point of one of the translocations, which is the only marker in 2RS.     

红球菌R04苯甲酸转运相关膜蛋白RHOGL009301的生理功能

【目的】探究红球菌(Rhodococcus sp.)R04膜蛋白RHOGL009301的生理功能和突变菌株的代谢特性,确定该膜蛋白的生理功能与苯甲酸转运的关系。【方法】将RHOGL009301基因与绿色荧光蛋白基因在Rhodococcus erythropolis进行融合表达,Delta Vision观察该基因蛋白产物的定位。通过基因同源重组敲除RHOGL009301基因,并对比野生型菌株和缺陷型菌株在不同碳源培养下的生长情况。HPLC测定红球菌R04野生型菌株和缺陷型菌株代谢联苯和苯甲酸时细胞内外代谢物,分析不同生长条件下代谢物的浓度变化。【结果】RHOGL009301基因与绿色荧光蛋白基因在Rhodococcus erythropolis中实现共表达,并定位在细胞膜上。获得了RHOGL009301基因的缺陷型菌株R04ΔMP,与野生型菌株相比,缺陷型菌株在联苯和苯甲酸培养条件下的生物量明显降低,生长速度减慢。HPLC分析表明RHOGL009301基因的缺失抑制了苯甲酸的转运。【结论】膜蛋白RHOGL009301是苯甲酸代谢和转运相关的蛋白,基于序列同源性分析,该膜蛋白是一种新型的苯甲酸转运蛋白。     

Small-molecule active pharmaceutical ingredients of approved cancer therapeutics inhibit human aspartate/asparagine-β-hydroxylase

Human aspartate/asparagine-β-hydroxylase (AspH) is a 2-oxoglutarate (2OG) dependent oxygenase that catalyses the hydroxylation of Asp/Asn-residues of epidermal growth factor-like domains (EGFDs). AspH is reported to be upregulated on the cell surface of invasive cancer cells in a manner distinguishing healthy from cancer cells. We report studies on the effect of small-molecule active pharmaceutical ingredients (APIs) of human cancer therapeutics on the catalytic activity of AspH using a high-throughput mass spectrometry (MS)-based inhibition assay. Human B-cell lymphoma-2 (Bcl-2)-protein inhibitors, including the (R)-enantiomer of the natural product gossypol, were observed to efficiently inhibit AspH, as does the antitumor antibiotic bleomycin A₂. The results may help in the design of AspH inhibitors with the potential of increased selectivity compared to the previously identified Fe(II)-chelating or 2OG-competitive inhibitors. With regard to the clinical use of bleomycin A₂ and of the Bcl-2 inhibitor venetoclax, the results suggest that possible side-effects mediated through the inhibition of AspH and other 2OG oxygenases should be considered.     

Structure of the Human Cation-Independent Mannose 6-Phosphate/IGF2 Receptor Domains 7–11 Uncovers the Mannose 6-Phosphate Binding Site of Domain 9

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