Hemokinins and endokinins

The mammalian tachykinins are a family of peptides that, until recently, has included substance P (SP), neurokinin A and neurokinin B. Since, the discovery of a third preprotachykinin gene (TAC4), the number of tachykinins has more than doubled to reveal several species-divergent peptides. This group includes hemokinin-1 (HK-1) in mouse and rat, endokinin-1 (EK-1) in rabbit, and EKA, EKB, human HK-1 (hHK-1) and hHK(4–11) in humans. Each exhibits a remarkable selectivity and potency for the tachykinin NK₁ receptor similar to SP. Their peripheral expression has led to the proposal that they are the endogenous peripheral SP-like endocrine/paracrine agonists where SP is not expressed. Moreover, their strong cross-reactivity with a specific SP antibody leads us to question many of the proposed locations and roles of SP in the periphery. Additionally, three orphan tachykinin gene-related peptides are identified on TAC4, in rabbit, EK-2 and in humans, EKC and EKD.Received 25 January 2004; received after revision 18 February 2004; accepted 27 February 2004     

4-Hydroxynonenal-modified amyloid-beta peptide inhibits the proteasome: possible importance in Alzheimer's disease

The amyloid β-peptide (Aβ) is a 4-kDa species derived from the amyloid precursor protein, which accumulates in the brains of patients with Alzheimer’s disease. Although we lack full understanding of the etiology and pathogenesis of selective neuron death, considerable data do imply roles for both the toxic Aβ and increased oxidative stress. Another significant observation is the accumulation of abnormal, ubiquitin-conjugated proteins in affected neurons, suggesting dysfunction of the proteasome proteolytic system in these cells. Recent reports have indicated that Aβ can bind and inhibit the proteasome, the major cytoslic protease for degrading damaged and ubiquitin-conjugated proteins. Earlier results from our laboratory showed that moderately oxidized proteins are preferentially recognized and degraded by the proteasome; however, severely oxidized proteins cannot be easily degraded and, instead, inhibit the proteasome. We hypothesized that oxidatively modified Aβ might have a stronger (or weaker) inhibitory effect on the proteasome than does native Aβ. We therefore also investigated the proteasome inhibitory action of Aβ _1–40 (a peptide comprising the first 40 residues of Aβ) modified by the intracellular oxidant hydrogen peroxide, and by the lipid peroxidation product 4-hydroxynonenal (HNE). H₂O₂ modification of Aβ _1–40 generates a progressively poorer inhibitor of the purified human 20S proteasome. In contrast, HNE modification of Aβ _1–40 generates a progressively more selective and efficient inhibitor of the degradation of fluorogenic peptides and oxidized protein substrates by human 20S proteasome. This interaction may contribute to certain pathological manifestations of Alzheimer’s disease Received 26 September 2000; accepted 26 September 2000     

动物抗菌肽的研究及应用

抗菌肽是具有抗菌活性的一类短肽,广泛存在于生物界.研究表明,除了具有广谱抗菌活性外,抗菌肽还具有抗病毒、抗真菌、抗寄生虫及抗肿瘤等生物活性.基于对抗菌肽的分类与特性、结构与活性、作用机理等方面进行系统的分析,综述了抗菌肽研究进展及应用前景.     

Study on peptide-peptide interaction using high-performance affinity chromatography and quartz crystal microbalance biosensor

The specific interaction between sense and antisense peptides was studied by high-performance affinity chromatography （HPAC） and quartz crystal microbalance （QCM） biosensor. Fragment 1-14 of human interferon-β （hlFN-βwas chosen as sense peptide and its three antisense peptides （AS-IFN 1, AS-IFN 2, and AS-IFN 3） were designed according to the degeneracy of genetic codes. The affinity column was prepared with sense peptide as ligand and the affinity chromatographic behavior was evaluated. Glu-substituted antisense peptide （AS-IFN 3） showed the strongest binding to immobilized sense peptide at pH 7.5. A quartz crystal microbalance-flow injection analysis （QCM-FIA） system was introduced to investigate the recognition process in real-time. The equilibrium dissociation constants between sense peptide and AS-IFN 1, AS-IFN 2 and AS-IFN 3 measured 2.08×10^-4, 1.31×10^-4 and 2.22×10^-5 mol/L, respectively. The mechanism study indicated that the specific recognition between sense peptide and AS-IFN 3 was due to sequence-dependent and multi-modal affinity interaction.     

Transport of a low molecular weight extracellular esterase into membrane vesicles ofCandida lipolytica

Summary The low mol. wt extracellular esterase ofCandida lipolytica is actively transported into membrane vesicles. In the absence of metabolic energy, a proton gradient can drive the transport process. The transport system does not accumulate the enzyme at peak levels due to the presence of a leak pathway.     

抗冻肽基因在热激表达盒式载体中的构建

克隆于细菌表达载体ｐ＾ＧＥＭ－３ｘｆ（－）中的ＡＦＰ基因经ＳａｌＩ和ＫｐｎＩＩ消化后，插入到热激盒式表达载体ｐ＾ＭＡ４１２的ＳａｌＩ和ＫｐｎＩ位点中，连接于可融合的报道基因元。     

固定化风味蛋白酶水解法生产高水解度大豆肽

采用固定化风味蛋白酶水解大豆蛋白生产大豆肽,以降低生产成本,同时提高水解度。通过单因素实验和响应面法对固定化风味蛋白酶法生产大豆肽的条件进行优化。结果表明,固定化风味蛋白酶法生产大豆肽的优化水解条件是65℃、pH值8.0、加酶量50g/L,酶解7h,水解度可达17.72%。固定化风味蛋白酶重复使用7次,相对酶活力仍高达79.1%。交联壳聚糖法制备的固定化风味蛋白酶具有良好的稳定性,可以重复多次使用,用于生产高水解度大豆肽是可行的,有利于降低生产成本。     

肽核酸在分子生物学技术和疾病治疗方面的应用（综述）

肽核酸是一种以多肽为骨架，类似核苷酸的物质，肽核酸与DNA或PNA有高度的亲和力和特异性，能够抑制基因的转录和翻译过程，在分子生物和肿瘤，艾滋病，病毒感染和其它难治性疾病的治疗方面有着广泛的应用前景。     

猪皮胶原肽-锌螯合物的制备工艺研究

研究猪皮胶原肽-锌螯合物的制备工艺。以猪皮为原料，制备猪皮胶原肽-锌螯合物；以螯合率为指标，研究了猪皮胶原肽与锌质量比、pH、温度、时间对螯合率的影响；通过单因素试验、响应面法试验考察优化猪皮胶原肽的富锌工艺。结果显示，猪皮肽-锌螯合的最佳工艺为猪皮肽与锌质量比2:1，螯合pH 7.0，螯合温度50 ℃，螯合时间50 min，在此条件下，试验螯合率最佳，为69.27%，与模型预测值69.92%相近。该研究为新型生物肽 锌螯合物的研制、猪皮的高值化利用提供了依据。