Carbachol-Induced Cosecretion of Immunoreactive Atrial Natriuretic Peptides with Catecholamines from Cultured Bovine Adrenal Medullary Cells

The distribution and secretion of atrial natriuretic peptides (ANPs) were investigated in bovine adrenal medulla. (1) Cultured bovine adrenal medullary cells (2 x 10(6)/dish) contained 100.4 +/- 6.0 fmol of immunoreactive ANP (IR-ANP) and 207.3 +/- 6.6 nmol of catecholamines as epinephrine plus norepinephrine. (2) Stimulation of nicotinic but not muscarinic acetylcholine receptors caused a cosecretion of IR-ANP and catecholamines corresponding to the ratio of IR-ANP to catecholamines in cultured bovine adrenal medullary cells. (3) Carbachol-stimulated secretion of IR-ANP was dependent on the presence of extracellular Ca2+. (4) Chromaffin granules isolated from bovine adrenal medulla contained large amounts of IR-ANP and catecholamines, in the same ratio as did cultured adrenal medullary cells. (5) Reverse-phase HPLC analysis showed that both stored and secreted IR-ANP consisted of two components, which eluted at the position of ANP(99-126) or ANP(1-126). These results indicate that ANPs are stored as ANP(99-126) and ANP(1-126) in chromaffin granules, and are cosecreted in parallel with catecholamines in a Ca2+-dependent manner by the stimulation of nicotinic acetylcholine receptors.     

Export of the periplasmic maltose-binding protein ofEscherichia coli

The export of the maltose-binding protein (MBP), themalE gene product, to the periplasm ofEschericha coli cells has been extensively investigated. The isolation of strains synthesizing MalE-LacZ hybrid proteins led to a novel genetic selection for mutants that accumulate export-defective precursor MBP (preMBP) in the cytoplasm. The export defects were subsequently shown to result from alterations in the MBP signal peptide. Analysis of these and a variety of mutants obtained in other ways has provided considerable insight into the requirements for an optimally functional MBP signal peptide. This structure has been shown to have multiple roles in the export process, including promoting entry of preMBP into the export pathway and initiating MBP translocation across the cytoplasmic membrane. The latter has been shown to be a late event relative to synthesis and can occur entirely posttranslationally, even many minutes after the completion of synthesis. Translocation requires that the MBP polypeptide exist in an export-competent conformation that most likely represents an unfolded state that is not inhibitory to membrane transit. The signal peptide contributes to the export competence of preMBP by slowing the rate at which the attached mature moiety folds. In addition, preMBP folding is thought to be further retarded by the binding of a cytoplasmic protein, SecB, to the mature moiety of nascent preMBP. In cells lacking this antifolding factor, MBP export represents a race between delivery of newly synthesized, export-competent preMBP to the translocation machinery in the cytoplasmic membrane and folding of preMBP into an export-incompetent conformation. SecB is one of threeE. coli proteins classified as molecular chaperones by their ability to stabilize precursor proteins for membrane translocation.     

Purification of thymocyte growth peptide (TGP) from sheep thymus. Relationship to FTS/thymulin

Thymocyte growth peptide (TGP) initiates DNA synthesis in immature thymocytes and has previously been characterized as an acidic peptide isolated from calf thymus. We now report the isolation of TGP from sheep thymus and show it to be a nonapeptide with a large N-terminal blocking moiety characterized by high UV absorbance. The amino acid composition is identical to FTS, consisting of 2 Gly, 2 Ser, 2 Glx, 1 Ala, 1 Lys, 1 Asx. In contrast to FTS, TGP is acidic with an apparent isoelectric point of 4.2 and a high UV absorbance at 270–280 nm. Reverse phase chromatography of TGP at an acidic pH results in a change of the molecule and the appearance of two new compounds TGP-A and TGP-B, both with less than 50% of the original TGP activity. Full activity could be restored by the addition of ZnCl₂ to TGP-A. Both TGP-A and B have some amino acid composition and high UV absorbance as native TGP. We propose that TGP consists of a non-peptide moiety bound to the N-terminal of the nonapeptide Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn and that the active molecule is stabilized by Zn²⁺.     

Nucleotide regulation of vasoactive intestinal peptide binding to bovine thyroid plasma membranes

The specific binding of vasoactive intestinal peptide (VIP) to bovine thyroid plasma membranes is inhibited by guanine nucleotides. Guanosine 5-triphosphate (GTP) and the non-hydrolyzable GTP analogs guanosine 5-,-imidotriphosphate (Gpp(NH)p) and guanosine 5-O-(3-thiotriphosphate) (GTP--S) inhibited markedly the binding of VIP to its receptors. This inhibition was higher with GTP than with Gpp(NH)p and GTP--S and was due to an increase of the rate of dissociation of peptide bound to membranes. Other nucleotides did not show any effect.     

Microwave irradiation increases recovery of neuropeptides from brain tissues

The effect of focused high energy microwave treatment (MW) on brain concentrations and molecular forms of substance P, neurokinin A, neuropeptide Y, neurotensin, galanin and calcitonin gene-related peptide was investigated. Groups of rats were treated as follows: 1) MW, storage for 60 min at 22°C, 2) Decapitation, storage for 60 min at 22°C, 3) Decapitation, storage for 60 min at 22°C, MW treatment, 4) MW, decapitation, storage for 2 min at 22°C and 5) Decapitation, storage for 2 min at 22°C. Peptide concentrations were in all instances highest in the MW sacrificed groups. MW increased the concentration of intact peptides by rapid inhibition of peptidase activity and increase in peptide solubility/extractability.     

人参多肽基因的化学合成和克隆

 本文报道了具有降血糖作用的人参多肽基因的设计及用固相亚磷酰胺法的合成。再以质粒pUC19作为克隆载体,以大肠杆菌JM101为受体菌,克隆了人参多肽基因,并成功地获得了克隆菌株。     

Activation of Protein Kinase C Augments Peptide Release from Rat Sensory Neurons

Abstract: To determine whether protein kinase C (PKC) mediates release of peptides from sensory neurons, we examined the effects of altering PKC activity on resting and evoked release of substance P (SP) and calcitonin gene-related peptide (CGRP). Exposing rat sensory neurons in culture to 10 or 50 n M phorbol 12,13-dibutyrate (PDBu) significantly increased SP and CGRP release at least 10-fold above resting levels, whereas the inactive 4α-PDBu analogue at 100 n M had no effect on release. Furthermore, 100 n M bradykinin increased peptide release approximately fivefold. Down-regulation of PKC significantly attenuated the release of peptides evoked by either PDBu or bradykinin. PDBu at 1 n M or 1-oleoyl-2-acetyl- sn -glycerol at 50 µ M did not alter resting release of peptides, but augmented potassium- and capsaicin-stimulated release of both SP and CGRP approximately twofold. This sensitizing action of PKC activators on peptide release was significantly reduced by PKC down-regulation or by pretreating cultures with 10 n M staurosporine. These results establish that activation of PKC is important in the regulation of peptide release from sensory neurons. The PKC-induced enhancement of peptide release may be a mechanism underlying the neuronal sensitization that produces hyperalgesia.     

Analysis of the Epitopes Recognized by Mouse Monoclonal Antibodies Directed to Yersinia enterocolitica Heat-Shock Protein 60

To determine amino acid sequences of the epitopes recognized by monoclonal antibodies (mAbs) 3C8 and 5C3 directed against Yersinia enterocolitica heat-shock protein (HSP60), a dot blot analysis was perfomed using synthesized peptides of Y. enterocolitica HSP60 such as peptides p316-342, p327-359, p340-366, p316-326, p316-321, p319-323, and p321-326 which represent positions of amino acids in Y. enterocolitica HSP60. The dot blot analysis revealed that 5C3 mAb reacted with p316-342, p316-326 and p321-326, and 3C8 mAb p316-342 and p316-326. These results indicate that the epitopes recognized by the mAbs were associated with eleven amino acids, Asp Leu Gly Gln Ala Lys Arg Val Val Ile Asn, of p316-326. The sequence homology between p316-326 of Y. enterocolitica HSP60 and the rest of the HSP60 family suggests that the five amino acids of Lys, Arg, Val, Ile and Asn, which are highly conserved in the HSP60 family, might be related with the epitope recognized by 3C8. In contrast, it was also demonstrated that three amino acids of Leu, Gly and Val, which are not well conserved in the HSP60 family, might be related to the epitope recognized by 5C3.     

反复电针对慢性痛的累加治疗作用及其机制研究

本研究从基础和临床两方面观察了反复电针对慢性痛的累加治疗作用,并结合疼痛患者及慢性痛动物模型中几种神经肽的放射免疫测定及相应受体拮抗剂的药理学研究结果,探讨了产生累加效应的可能机制。结果表明,在临床脊髓损伤性痉挛患者,１００Ｈｚ穴位体表电刺激有效地缓解痉挛并有累加效应;在临床慢性痛患者,２／１５Ｈｚ变频ＴＥＮＳ刺激有效地治疗疼痛并具有累加效应。在关节炎模型大鼠,电针刺激能产生明显的镇痛并具有累加效