Staurosporine,a Prolyl Endopeptidase Inhibitor

The filamentous fungus Monascus pilosus was genetically transformed with a reporter plasmid, pMS-1.5hp, by aurintricarboxylic acid (ATA) treatment to obtain an efficient red-pigment producing mutant. The transformation efficiency of Monascus pilosus was higher with the ATA-treatment than with either a non-restriction-enzyme-mediated integration (REMI) or a REMI method. This valid and convenient random mutagenesis method shows that ATA can be applied in fungi for efficient genetic transformation.     

脯氨酰内肽酶研究进展

脯氨酰内肽酶(prolyl endopeptidase,PEP)［EC3.4.21.26］是一种能特异性水解多肽链中脯氨酸残基羧基端肽键的丝氨酸蛋白酶,能降解许多多肽类神经递质和激素,其活性的异常会引起精神、认知过程的障碍.一些PEP的专一性抑制剂(如JTP-4819)显示在莨菪胺引起的小鼠记忆障碍模型中有改善记忆的药理作用.猪肌肉PEP晶体结构的解析推动了PEP的研究.     

重组点状产气单胞菌脯氨酰内肽酶的性质

以特异性底物和多态的对大肠杆菌表达的重组点状产气单胞菌脯氨酰内肽酶（简称ａｐＰＥＰ）催化性质的研究表明,ａｐＰＥＰ在４～３２℃比较稳定,最适催化温度为３４℃;在ｐＨ６～１０比较稳定,最适ｐＨ为８．４;ａｐＰＥＰ的比活力为６７．６ｕ／ｍｇ。对Ｚ－Ｇｌｙ－Ｐｒｏ－βＮＡ底物的酶解常数Ｋｍ为０．０３ｍｍｏｌ／Ｌ。一些蛋白酶抑制剂和金属离子的抑制作用结果表明,ａｐＰＥＰ不受ＰＭＳＦ、ＴＬＣＫ、ＴＰＣＫ、胰     

Subcellular Distribution of Prolyl Endopeptidase and Cation-Sensitive Neutral Endopeptidase in Rabbit Brain

Abstract: The subcellular distribution of prolyl endopeptidase, and of cationsensitive neutral endopeptidase, two enzymes actively metabolizing many neuropeptides, was determined in homogenates of rabbit brain. The subcellular distribution of both enzymes was more similar to lactate dehydrogenase, a cytoplasmic enzyme marker, than to choline acetyltransferase, a synaptosomal marker. Only 35% of the activity of these two neutral endopeptidases was found in the crude mitochondrial fraction (P₂), the bulk of the remaining activity being associated with the high-speed supernatant. Prolyl endopeptidase and cation-sensitive neutral endopeptidase thus can be regarded as mainly cytoplasmic enzymes in the rabbit brain.     

重组点状产气单胞菌脯氨酰内肽酶的纯化和鉴定

报道重组点状产气单胞菌脯氨酰内肽酶(简称apPEP)的基因工程下游工艺研究。工程菌株E.coli BL21/pKKH\|PEP表达产物apPEP为可溶性蛋白,在NBS BioFlo 3000型5L自控发酵罐中经14h培养每升发酵液可达到22.5g干重菌体,含apPEP 3.0g左右。发酵菌体经超声破碎、硫酸铵沉淀后,依次经Sephadex G-25、High performance Q sepharose FF(HP\|Q)、Phenyl separose 6 FF柱层析分离纯化,每升发酵产物最终可得0.86g纯度达96%的重组apPEP,比活力达到65.5u/mg,整个纯化工艺的蛋白回收率为8.2%,活力回收率为24.4%。纯化的apPEP经电喷雾质谱测定分子量为76464±30D,N端氨基酸序列与基因序列推导的一致。等电点为pI6.0左右。与Aeromonas hydrophila来源的PEP(pI=5.5)相近。     

Effect of a Novel Prolyl Endopeptidase Inhibitor, JTP-4819, on Prolyl Endopeptidase Activity and Substance P- and Arginine-Vasopressin-Like Immunoreactivity in the Brains of Aged Rats

Abstract: The effects of a novel prolyl endopeptidase (PEP) inhibitor, ( S )-2-[[( S )-2-(hydroxyacetyl)-1-pyrrolidinyl]carbonyl]- N -(phenylmethyl)-1-pyrrolidinecarboxamide (JTP-4819), on the PEP activity in the brain and on the contents of substance P (SP)- and arginine-vasopressin (AVP)-like immunoreactivity (LI) in the cerebral cortex and hippocampus of young and aged rats were investigated using enzyme immunoassay. JTP-4819 exhibited a concentration-dependent in vitro inhibitory action on PEP activity in the brains of both young and aged rats, with IC₅₀ values of ∼0.7 and 0.8 n M , respectively. A single dose of JTP-4819 (3 mg/kg, p.o.) increased the SPLI content in the cerebral cortex but not the hippocampus of aged rats (23–24 months old). In addition, repeated administration of JTP-4819 (1 mg/kg, p.o., for 21 days) increased the SPLI content in the cerebral cortex and restored the SPLI content in the hippocampus, which had decreased with aging. In contrast, single (1 mg/kg, p.o.) and repeated (1 mg/kg, p.o., for 21 days) administration of JTP-4819 only tended to increase the AVPLI content of the hippocampus and cerebral cortex in aged rats, respectively. These results indicate that JTP-4819 increases the cerebral and hippocampal SPLI content in aged rats by inhibiting the action of PEP.     

脯氨酰内肽酶培养条件的优化及高密度发酵

基因工程菌E.coliBL21/pGEMPEP可以组成型表达重组的点状产气单胞菌脯氨酰内肽酶(PEP),但培养条件极大地影响着酶的产量,为了获得高效表达,首先测定了工程菌表达PEP的稳定性并考察了培养温度、pH、发酵时间、碳源、氮源、无机盐等对产酶的影响,得到了优化的发酵条件,L9(3⁴)正交试验进一步明确了摇床转速、培养温度、pH值、培养时间对产酶量的影响都有高度的统计学意义。在此基础上利用NBSBioFlo3000型5L自控发酵罐进行了高密度、高表达发酵、经20h培养,最终菌体密度达OD₆₀₀60(相当于干菌体225g/L),PEP表达量为28%,每升发酵液中含PEP酶315g。     

Inhibition of Rabbit Brain Prolyl Endopeptidase by N-Benzyloxycarbonyl-Prolyl-Prolinal, a Transition State Aldehyde Inhibitor

Prolyl endopeptidase cleaves peptide bonds on the carboxyl side of proline residues within a peptide chain. The enzyme readily degrades a number of neuropeptides including substance P, neurotensin, thyrotropin-releasing hormone, and luteinizing hormone-releasing hormone. The finding that the enzyme is inhibited by benzyloxycarbonyl-prolyl-proline, with a Ki of 50 microM, prompted the synthesis of benzyloxycarbonyl-prolyl-prolinal as a potential transition state analog inhibitor. Rabbit brain prolyl endopeptidase was purified to homogeneity for these studies. The aldehyde was found to be a remarkably potent inhibitor of prolyl endopeptidase with a Ki of 14 nM. This Ki is more than 3000 times lower than that of the corresponding acid or alcohol. By analogy with other transition state inhibitors, it can be assumed that binding of the prolinal residue to the S1 subsite and the formation of a hemiacetal with the active serine of the enzyme greatly contribute to the potency of inhibition. The specificity of the inhibitor is indicated by the finding that a variety of proteases were not affected at concentrations 150 times greater than the Ki for prolyl endopeptidase. The data indicate that benzyloxycarbonyl-prolyl-prolinal is a specific and potent inhibitor of prolyl endopeptidase and that consequently it should be of value in in vivo studies on the physiological role of the enzyme.     

点状产气单胞菌脯氨酰内肽酶在大肠杆菌中的高效表达

采用ＰＣＲ分段克隆法将点状产气单胞菌点状亚种（Ａｅｒｏｍｏｎａｓ ｐｕｃｔａｔａ ｓｕｂｓｐ．ｊｐｕｃｔａｔａ）脯氨酰内肽酶（ｐｒｏｌｙｌ ｅｎｄｏｐｅｐｔｉｄａｓｅ,ａｐＰＥＰ）的编码区基因分成３段扩增并拼接成编码６９０个氨基酸的完整基因ａｐＰＥＰ,将其克隆在表达载体ｐＢＬ和ｐＫＫＨ上,构建成温度和ＩＰＴＧ诱导型高效表达ａｐＰＥＰ的重组大肠杆菌ＢＬ２１／ｐＢＬ－ＰＥＰ和ＢＬ２１／ｐＫＫＨ－ＰＥＰ     

点状产气单胞菌脯氨酰内肽酶基因克隆与序列测定

点状产气单胞菌点状亚种（Ａｅｒｏｍｏｎａｓ ｐｕｎｃａｔａ ｓｕｂｓｐ．ｐｕｎｃｔａｔａ）具有脯氨酰内肽酶（ｐｒｏｌｙｌ ｅｎｄｏｐｅｐｔｉｄａｓｅ ＰＥＰ）活性。将其染色体ＤＮＡ有Ｅｃｏ ＲⅠ部分酶切后回收８－１６ｋｂ的ＤＮＡ片段,与ＥｃｏＲⅠ消化载体ｐＵＣ１８连接后转化Ｅ．ｃｏｉｌ ＤＨ５α,用该酶的专一性底物Ｂｅｎｚｙｌｏｘｙｃａｒｂｏｎｙｌ－Ｇｌｙ－β－ｎａｐｈｔｈｙｌａｍｉｄｅ从质粒库中     

Development of a Membrane-anchored Chemerin Receptor Agonist as a Novel Modulator of Allergic Airway Inflammation and Neuropathic Pain

The chemerin receptor (CMKLR1) is a G protein-coupled receptor found on select immune, epithelial, and dorsal root ganglion/spinal cord neuronal cells. CMKLR1 is primarily coupled to the inhibitory G protein, Gα_i, and has been shown to modulate the resolution of inflammation and neuropathic pain. CMKLR1 is activated by both lipid and peptide agonists, resolvin E1 and chemerin, respectively. Notably, these ligands have short half-lives. To expedite the development of long acting, stable chemerin analogs as candidate therapeutics, we used membrane-tethered ligand technology. Membrane-tethered ligands are recombinant proteins comprised of an extracellular peptide ligand, a linker sequence, and an anchoring transmembrane domain. Using this technology, we established that a 9-amino acid-tethered chemerin fragment (amino acids 149–157) activates both mouse and human CMKLR1 with efficacy exceeding that of the full-length peptide (amino acids 21–157). To enable in vivo delivery of a corresponding soluble membrane anchored ligand, we generated lipidated analogs of the 9-amino acid fragment. Pharmacological assessment revealed high potency and wash resistance (an index of membrane anchoring). When tested in vivo, a chemerin SMAL decreased allergic airway inflammation and attenuated neuropathic pain in mice. This compound provides a prototype membrane-anchored peptide for the treatment of inflammatory disease. A parallel approach may be applied to developing therapeutics targeting other peptide hormone G protein-coupled receptors.     

Prolyl cis-trans isomerization as a molecular timer

Proline is unique in the realm of amino acids in its ability to adopt completely distinct cis and trans conformations, which allows it to act as a backbone switch that is controlled by prolyl cis-trans isomerization. This intrinsically slow interconversion can be catalyzed by the evolutionarily conserved group of peptidyl prolyl cis-trans isomerase enzymes. These enzymes include cyclophilins and FK506-binding proteins, which are well known for their isomerization-independent role as cellular targets for immunosuppressive drugs. The significance of enzyme-catalyzed prolyl cis-trans isomerization as an important regulatory mechanism in human physiology and pathology was not recognized until the discovery of the phosphorylation-specific prolyl isomerase Pin1. Recent studies indicate that both phosphorylation-dependent and phosphorylation-independent prolyl cis-trans isomerization can act as a novel molecular timer to help control the amplitude and duration of a cellular process, and prolyl cis-trans isomerization might be a new target for therapeutic interventions.     

Long-Term Social Isolation Reduces Expression of the BDNF Precursor and Prolyl Endopeptidase in the Rat Brain

Biochemistry (Moscow) - Early-life stress is a risk factor for the development of behavioral and cognitive disorders in humans and animals. Such stressful situations include social isolation in...     

Age-Related Decline of Neutrophilic Inflammation Is Associated with Better Postoperative Prognosis in Non-eosinophilic Nasal Polyps

Background

Innate and adaptive immune responses change with increasing age and affect the course of diseases. Previous study investigated immunologic alteration in Western nasal polyps (NP) which is mostly eosinophilic. However, there are no reports regarding age-related immune changes of non-eosinophilic NP (NE-NP) which is a predominant subtype in Asian population.

Methods

A total of 153 subjects, including 20 with control, 63 with chronic rhinosinusitis (CRS) without NP (CRSsNP), and 70 with CRS with NP were enrolled. Age-related changes in computed tomography (CT), cytokines and clinical information were investigated. Tissue samples were analyzed for protein levels of IL-5, IL-17A, IL-23, interferon (IFN)-γ, CCL-11, and CXCL-8, using Luminex immunoassay and for mRNA expression levels of interleukin (IL)-5, IL-17A, IL-23p19, IFN-γ, CCL-11, CXCL-1, CXCL-2, CXCL-8, and CXCR2 by quantitative RT-PCR. Immunohistochemistry (IHC) was performed for the number of inflammatory cells.

Results

We observed that Lund-Mackay CT scores decreased with age in NE-NP. The number of human neutrophil elastase-positive cells and myeloperoxidase gene expression decreased in older patients with NE-NP, but not in control subjects, CRSsNP, and E-NP. Neutrophil-associated cytokines including IL-17A and IL-23, were negatively correlated with age in NE-NP at the protein and mRNA levels. Additionally, the expression of CXCR2, a receptor for CXCL-1 and CXCL-2, was decreased with age in NE-NP. However, there were no age-related changes in blood neutrophil count, and neutrophil-recruiting chemokines such as CXCL-1, CXCL-2, and CXCL-8. Elderly NE-NP patients showed better endoscopic scores at 12 months after surgery compared with the non-elderly.

Conclusion

Age-related decline in neutrophil inflammation may favorably affect postoperative results in elderly patients with NE-NP.     

Changes in Prolyl Endopeptidase During Maturation of Rat Brain and Hydrolysis of Substance P by the Purified Enzyme

We determined changes in prolyl endopeptidase activity in developing rat brain. A new and highly sensitive fluorogenic substrate, 7-(succinyl-Gly-Pro)-4-methylcoumarinamide, was used for determination of the enzyme activity. The enzyme activity per brain increased until 2 weeks of age, and then decreased during maturation. The enzyme was purified about 7800-fold from the brain of the rat at 2 or 3 weeks of age. The enzyme has a pH optimum of 5.8 to 6.5, and an approximate molecular weight of 70,000. The enzyme activity was completely inhibited by low concentrations of diisopropylfluorophosphate and partially inhibited by high concentrations of phenylmethanesulphonylfluoride, which are potent serine protease inhibitors. Moreover, thiolblocking agents and some heavy metals also have a strong effect on the activity. Bacitracin was found to be a potent inhibitor, with an IC50 value of 2.5 x 10(-6) M at 0.5 mM of the substrate. The enzyme was proved to hydrolyze the NH2-terminal tetrapeptide. Arg1-Pro2-Lys3-Pro4, from substance P to produce the heptapeptide, Gln5-Gln6-Phe7-Phe8-Gly9-Leu10-Met11-CONH2. The Km value of the hydrolysis of substance P was 1.0 mM. This enzyme may be related to the regulation of substance P in the brain, and to the development of neurones by forming the tetrapeptide because the tetrapeptide has almost the same effect as substance P on the neurite extension of neuroblastoma.     

MicroRNA 320a Functions as a Novel Endogenous Modulator of Aquaporins 1 and 4 as Well as a Potential Therapeutic Target in Cerebral Ischemia

Aquaporins facilitate efficient diffusion of water across cellular membranes, and water homeostasis is critically important in conditions such as cerebral edema. Changes in aquaporin 1 and 4 expression in the brain are associated with cerebral edema, and the lack of water channel modulators is often highlighted. Here we present evidence of an endogenous modulator of aquaporin 1 and 4. We identify miR-320a as a potential modulator of aquaporin 1 and 4 and explore the possibility of using miR-320a to alter the expression of aquaporin 1 and 4 in normal and ischemic conditions. We show that precursor miR-320a can function as an inhibitor, whereas anti-miR-320a can act as an activator of aquaporin 1 and 4 expressions. We have also shown that anti-miR-320a could bring about a reduction of infarct volume in cerebral ischemia with a concomitant increase in aquaporins 1 and 4 mRNA and protein expression.     

Delineation of a Particulate Thyrotropin-Releasing Hormone-Degrading Enzyme in Rat Brain by the Use of Specific Inhibitors of Prolyl Endopeptidase and Pyroglutamyl Peptide Hydrolase

The degradation of thyrotropin-releasing hormone in rat brain homogenates was studied in the presence of N-benzyloxycarbonyl-prolyl-prolinal and pyroglutamyl diazomethyl ketone, specific and potent active-site-directed inhibitors of prolyl endopeptidase and pyroglutamyl peptide hydrolase, respectively. Substantial TRH degradation was observed, suggesting the presence of another thyrotropin-releasing hormone-degrading enzyme(s). Reports of a thyrotropin-releasing hormone-degrading enzyme with narrow specificity that cleaves the pGlu-His bond of this tripeptide led us to develop a coupled assay using pGlu-His-Pro-2NA as the substrate to measure this activity. Cleavage of the pGlu-His bond of this substrate under conditions in which pyroglutamyl peptide hydrolase is not expressed occurred in the particulate fraction of a rat brain homogenate. This particulate pyroglutamyl-peptide cleaving enzyme was not inhibited by pyroglutamyl diazomethyl ketone but was inhibited by metal chelators such as EDTA and o-phenanthroline. The particulate pyroglutamyl-peptide cleaving enzyme was found predominantly in the brain. Activity in brain regions varied widely with highest levels present in cortex and hippocampus and very low levels in pituitary. The data suggest that degradation of thyrotropin-releasing hormone by the particulate fraction of a brain homogenate is catalyzed mainly by an enzyme that cleaves the pGlu-His bond of thyrotropin-releasing hormone but is distinct from pyroglutamyl peptide hydrolase.     

Prolyl isomerization as a molecular timer in phage infection

Prolyl cis-trans isomerizations are intrinsically slow reactions and known to be rate-limiting in many protein folding reactions. Here we report that a proline is used as a molecular timer in the infection of Escherichia coli cells by the filamentous phage fd. The phage is activated for infection by the disassembly of the two N-terminal domains, N1 and N2, of its gene-3-protein, which is located at the phage tip. Pro213, in the hinge between N1 and N2, sets a timer for the infective state. The timer is switched on by cis-to-trans and switched off by the unusually slow trans-to-cis isomerization of the Gln212-Pro213 peptide bond. The switching rate and thus the infectivity of the phage are determined by the local sequence around Pro213, and can be tuned by mutagenesis.     

Blood–Brain Barrier Transport of Valproic Acid

Valproic acid distribution in brain is less than that of other anticonvulsants such as phenytoin or phenobarbital. Possible mechanisms for this decreased distribution space in brain include (a) increased plasma protein binding of valproate relative to the other anticonvulsants and (b) asymmetric blood-brain barrier (BBB) transport of valproate such that the brain-to-blood flux exceeds the blood-to-brain flux. These mechanisms are investigated in the present studies using the intracarotid injection technique in rats and rabbits. In the rat, the brain uptake index (BUI) of [14C]valproate relative to [3H]water is 51 +/- 6%, indicating the blood-to-brain transport of water is twofold greater than that of valproate. However, the BUI of [14C]valproate relative to [3H]water decreased with time after carotid injection during a 4-min washout period, which indicates that brain-to-blood transport of valproate is greater than that of water. This suggests that the permeability of the BBB to valproate is polarized, with antiluminal permeability being much greater than luminal permeability. In rabbits, the BUI of [14C]valproate is 47 +/- 7% in newborns and 17 +/- 6% in adult animals. However, the high drug extraction in newborns may be attributed to decreased cerebral blood flow in the neonate as the BBB permeability-surface area (PS) products are unchanged (e.g., PS = 0.13 and 0.11 ml min-1 X g-1 in the newborn and adult rabbit, respectively). With regard to plasma protein binding effects on valproate transport, brain valproate uptake was also measured in the presence of human, lamb, pig, rat, horse, goat, hamster, dog, and mouse sera. Higher brain uptakes were observed when the unbound fraction of drug increased. However, our data indicate that a fraction of the valproic acid entering the capillaries bound to plasma proteins had the capacity to equilibrate with brain because of enhanced drug dissociation from albumin in the brain microcirculation. Since plasma protein-bound valproate is available for uptake by brain, the major factor underlying the diminished distribution of the drug in brain appears to be the asymmetric transport properties of the BBB to valproic acid.     

具靶向性的转铁蛋白—脂质体的制备

具靶向性的转铁蛋白──脂质体的制备杨静平,王瓞,林其谁（中国科学院上海生物化学研究所分子生物学国家重点实验室,２０００３１）关键词脂质体;人转铁蛋白;靶向性;癌细胞;天花粉蛋白利用正常细胞和癌细胞表面受体或抗原物质的差异,用相应配体修饰脂质体表面,使...