Observations of light-induced structural changes of retinal within rhodopsin

Photo-isomerization of the 11-cis retinal chromophore activates the mammalian light-receptor rhodopsin, a representative member of a major superfamily of transmembrane G-protein-coupled receptor proteins (GPCRs) responsible for many cell signal communication pathways. Although low-resolution (5 A) electron microscopy studies confirm a seven transmembrane helix bundle as a principal structural component of rhodopsin, the structure of the retinal within this helical bundle is not known in detail. Such information is essential for any theoretical or functional understanding of one of the fastest occurring photoactivation processes in nature, as well as the general mechanism behind GPCR activation. Here we determine the three-dimensional structure of 11-cis retinal bound to bovine rhodopsin in the ground state at atomic level using a new high-resolution solid-state NMR method. Significant structural changes are observed in the retinal following activation by light to the photo-activated M(I) state of rhodopsin giving the all-trans isomer of the chromophore. These changes are linked directly to the activation of the receptor, providing an insight into the activation mechanism of this class of receptors at a molecular level.     

Enzyme-linked immunosorbent assay to detect anti-sea nettle venom antibodies

Summary A micro enzyme-linked immunosorbent assay has been developed to detect serum antibodies to sea nettle venom. This sensitive assay is useful for monitoring specific immunological response in envenomated patients or in immunized animals.These experiments were funded in part by grant ES01474 from the National Institutes of Health and the Brandywine Foundation. The authors wish to acknowledge the technical aid and assistance of Helene Rubinstein and Robert Miller.     

大型办公楼配电系统的谐波评估与抑制

为评估大型办公楼配电系统的谐波水平,寻求抑制谐波的方法,对该系统的特点进行了分析．应用公用电网谐波国家标准,确定了两层公共连接点（ＰＣＣ）上的谐波限值．在香港的１４ 座办公楼中对各ＰＣＣ的谐波水平进行了评估．发现有些情况下电压和电流的谐波畸变水平都超出了限定值,租户供电电路的谐波畸变尤其严重,有些直立干线上的电压总谐波畸变率甚至超过１５％ ．对照明、小功率用电和空调电路等分支电路中的谐波情况也进行了调查,总结了其谐波特点．基于对谐波评估结果的分析,提出了控制谐波源,减小直立干线阻抗,均衡布置非线性负荷,利用谐波的集合效应等谐波抑制措施．     

重载流多芯电缆周围的磁场 Ⅱ. 数值计算和测量

重载流无铠装多芯电缆周围磁场的特性可以用载流平行螺旋线理论模型来解释,而据此推导的简化计算公式可方便地估算电缆周围的磁场,为验证该理论模型的有效性和间化公式的准确度,对电缆周围的极低频磁场进行了基于毕奥－沙伐定律的数值计算和实测,通过数值计算结果和实测值与简化公式估算结果之间的比较,证明了该理论模型的有效性,发现简化计算公式对距电缆轴线0．2m以外的磁场有很高的估算精度,另外,还讨论了电缆所载电流的特性对周围磁场的影响,并提出一些降低多芯电缆系统周围磁场的方法。     

The inhibition of cathepsin B by plasma haptoglobin biochemistry (enzymes,metabolism)

Summary Purified haptoglobin partially inhibits the activity of a lysosomal thiol proteinase, cathepsin B. This inhibition is reversible in the presence of monospecific antiserum to haptoglobin.This work was supported by an East Anglian Regional Health Authority Grant.