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21.
N. Avramovitch A. Hoffman J. Winaver A. Haramati D. Lewinson 《Cell and tissue research》1995,279(3):575-583
The morphometric characteristics of atrial natriuretic peptide-containing granules were studied in atrial myoendocrine cells of rats with aorto-caval fistula, an experimental model of congestive heart failure. A total of 6680 granules of control and aorto-caval rats were analyzed by a computerized image analysis system that evaluated the number and sectioned surface area of granules and their subcellular location. Compared with control animals, rats with congestive heart failure displayed a slight increase in the number of peripheral granules, adjacent to the sarcolemma, but not centrally located in the Golgi areas. The mean sectioned surface area of granules in rats with congestive heart failure was about 50% of that in controls, both in the right and left atria. Rats with aortocaval fistula had a higher percent of small granules and lower percent of large granules compared with controls. The data demonstrate different morphometric characteristics in atrial natriuretic peptide-containing granules in atriocytes in rats with experimental congestive heart failure; this may reflect the enhanced synthesis and release of atrial natriuretic peptide in heart failure. 相似文献
22.
Summary Opioid peptides are thought to interact with the cell membrane in their biological journey to the membrane-bound receptor. Both organic solvents and model membranes have been used previously to determine the stable solution conformations of peptide hormones. Leucine enkephalin has been studied in a number of different environments, but with limited resolution. Here it is shown that leucine enkephalin forms a stable type IV -turn structure in dodecylphosphocholine micelles. We have observed a highly solvent-shielded amide proton with no evidence for a complementary hydrogen bond acceptor. The structural details of the peptide as determined by NMR spectroscopy in solution are described. 相似文献
23.
F. Leboulenger I. Perroteau P. Netchitailo I. Lihrmann P. Leroux C. Delarue D.H. Coy H. Vaudry 《Peptides》1984,5(2):299-303
Vasoactive intestinal peptide (VIP) is located in chromaffin cells of the frog adrenal gland and is able to stimulate corticosteroid secretion in amphibians. In the present study we have investigated the possible involvement of prostaglandins, microfilaments and calcium in the mechanism of action of VIP on frog adrenocortical tissue. Rana ridibunda interrenal dice were perifused with amphibian culture medium for more than 10 hours. Corticosterone and aldosterone concentrations were measured in the effluent perifusate using sensitive and specific radioimmunoassay methods. In the presence of indomethacin (5 μM), a specific blocker of prostaglandin biosynthesis, the spontaneous secretion of corticosteroids was markedly reduced (80%) but the stimulatory effect of VIP was not altered. The administration of the microfilament disrupting agent cytochalasin B (50 μM) inhibited both spontaneous and VIP-induced corticosteroid secretion. In the absence of calcium, the spontaneous level of corticosteroid was reduced to about 60% but VIP was still able to stimulate corticosteroid secretion. From these data we conclude that the integrity of the cytoskeleton is required for the secretory response of adrenocortical cells to VIP, whereas neither prostaglandins nor calcium are involved in VIP-induced adrenocortical stimulation. 相似文献
24.
PHI--a new brain-gut peptide 总被引:3,自引:0,他引:3
K Tatemoto 《Peptides》1984,5(2):151-154
The detection of the C-terminal amide structure in porcine intestinal extracts has led to the discovery of a 27 amino acid residue peptide designated PHI (PHI-27, peptide HI). The peptide was found to have structural homologies to vasoactive intestinal peptide (VIP) and growth hormone-releasing factor (GRF). Subsequent studies have revealed that PHI exhibits a variety of biological activities which resemble those of VIP. Moreover, it was found that the peptide is able to inhibit the binding of VIP to its receptors, and to stimulate cyclic AMP production. PHI is present in both brain and gut in high concentrations and probably acts as a neurotransmitter or neuromodulator rather than a hormone. A comparison of the amino acid sequences of porcine, human and bovine PHI indicated that human PHI differs from the porcine peptide in two positions (12 and 27), and bovine PHI differs in one position (10). The amino acid sequence (deduced from the cDNA sequence) of the VIP precursor recently obtained from human neuroblastoma cells also contains an identical sequence to the newly-isolated human PHI from human colonic extracts. PHI has thus been shown to be co-synthesized with VIP in the same precursor molecule. 相似文献
25.
Stimulation of the adenylate cyclase of A B16 melanoma cell line by pro-opiocortin-related peptides--a structure-activity study 总被引:1,自引:0,他引:1
The ability of alpha-melanotrophin (alpha-MSH or ACTH 1-acetyl-13 amide) and other structurally related peptides derived from the common precursor, pro-opiocortin, to stimulate adenylate cyclase activity in a pigmented B16 mouse melanoma was investigated. The peptides ACTH 1-39, ACTH 1-24, alpha-MSH, ACTH 1-13 amide and beta-MSH all stimulated the enzyme to a similar maximal extent and with similar potency (ED50 = 1.3 . 10(-6) M) except that ACTH 1-39 was slightly less potent (ED50 = 5 . 10(-6) M). ACTH 4-10 (ED50 = 4 . 10(-5) M) and gamma-MSH (ED50 = 5 . 10(-6) M) were partial agonists. ACTH 1-10 was no more effective than ACTH 4-10 in stimulating the enzyme whereas ACTH 1-13 amide was a full agonist. The peptides beta-endorphin and its derivatives, Met-enkephalin and melanotrophin potentiating factor (MPF), failed to stimulate the enzyme. We suggest that the B16 melanoma requires not only the sequence ACTH 4-10 but also some part of the sequence ACTH 11-13, or a similar sequence in the terminal portion of beta-MSH, for full activation of the receptor-linked enzyme. 相似文献
26.
27.
N. C. Smith 《International journal for parasitology》1992,22(8):1047-1082
28.
家蚕神经肽基因的筛查及成熟肽的预测 总被引:1,自引:0,他引:1
神经肽(neuropeptide)是家蚕Bombyx mori体内重要的调控物质。为了充分理解神经肽对家蚕发育的调控, 扩充家蚕神经肽的数量, 本研究利用BLAST的tblastn程序结合OpenOffice软件的查找程序, 基于其他昆虫和无脊椎动物神经肽的同源性和保守的结构特点, 在家蚕基因、理论蛋白质数据库及NCBI中进行全面而系统的基因筛查; 并利用各种在线工具对所筛查到基因和理论蛋白质的结构和成熟肽进行预测分析。结果共获得allatostatin-A (AST-A), allatostatin-B (AST-B), allatostatin-C (AST-C), allatropin (AT), ecdysis-triggering hormone (ETH), crustacean cardioactive peptide (CCAP)和FMRFamide等31个神经肽基因家族, 包括37个神经肽基因亚家族, 共计44个神经肽基因; 预测出193个成熟的神经肽, 其中73个根据家族同源性预测在C末端发生酰胺化, 而6个被预测在N末端发生了环化, 9个被预测酪氨酸发生了硫酸化。大部分成熟神经肽都具有明显的家族结构特征, 但proctolin, CCAP及CAPA-PK成熟肽结构上与其他昆虫相比有所扩展。结果提示, 家蚕神经和内分泌细胞产生了几乎在所有昆虫中具有的神经肽前体; 进化过程中大部分成熟神经肽的氨基酸序列在种间产生了差异, 但家族特征性基序高度保守。本研究为神经肽功能研究以及神经肽对家蚕发育尤其是蛹期发育调控的研究奠定了基础。 相似文献
29.
Peter Hammershøj Mikkel Jessing Anders Ø. Madsen Knud J. Jensen Jørn B. Christensen Ulrik Boas 《International journal of peptide research and therapeutics》2007,13(1-2):209-212
The development of new linkers (handles) for solid-phase synthesis provides new chemical opportunities for peptide synthesis.
To understand the chemical properties of a recently developed backbone amide linker from a structural perspective, the crystal
structure of S-((5-formyl-3,4-ethylenedioxy)thiophene-2-yl)-3-thiopropionic acid (T-BAL2) was studied. Specifically, we wished
to address whether this highly substituted thiophene retained planarity in the aromatic ring as well as between the aromatic
ring and the aldehyde carbonyl. Furthermore, we sought an explanation for the relatively low reactivity in reductive aminations
of the thienylaldehyde with amines in solution and on solid phase. Based on the crystal structure of T-BAL2, the thienyl-C
(aldehyde) and C–O (aldehyde) bond lengths were applied as measures for the electron-deficiency (electrophilicity) of the
aldehyde and compared to similar bond lengths found in previously reported formylated homo- and hetero-aromatic systems, which
show significantly higher reactivity towards imine formation. The bond lengths found in the present structure are in accordance
with normal C–C single bond and C–O double bond lengths. The high similarity in aldehyde bond lengths in the present system
and in the reported systems indicates similar electron distribution in these systems. The lower reactivity of the present
system may therefore not be attributed to electronic factors. 相似文献
30.
HE Xiaolin LIU Xinqi ZENG Zonghao LI Hongmin WANG Miao ZHANG Ying WANG Dacheng 《中国科学C辑(英文版)》2000,43(1):39-46
BmK M4 is a neutral neurotoxin in the BmK toxin series.It is medially toxic and belongs to group III α-toxins.The purified sample was crystallized in rhombic space group P61.Using an X-ray diffraction technique,the crystal structure of BmK M4 was revealed by molecular replacement at 0.20 nm resolution.The model was refined.The final crystallographic R factor was 0.142 and the free R factor was 0.173.The root mean square deviation is 0.001 5 nm for the bond length and 1.753°for the bond angles.64 water molecules were added to the asymmetric unit.The refined structure showed an unusual non-prolyl cis peptide bond at residue 10.The structure was compared with group II α-toxin BmK M8 (an acidic,weak toxin).The potential structural implications of the cis peptide bond were discussed. 相似文献