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J M Conlon

Publications and source records attributed to J M Conlon.

At least 199 records · Page 11Linked to original sources
PubMed1992

Structural characterization of tachykinins (neuropeptide gamma, neurokinin A, and substance P) from a reptile, Alligator mississipiensis.

An extract of the whole brain of the alligator (Alligator mississipiensis) contained very high concentrations of substance P-like immunoreactivity (405 pmol/g wet tissue) and neurokinin A-like immunoreactivity (514 pmol/g), as measured with antisera raised against the mammalian peptides. The primary structure of alligator substance P was established as: Arg-Pro-Arg-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2. This sequence is the same as that of chicken substance P and shows one substitution (Arg for Lys3) as compared with mammalian substance P. The neurokinin A-like immunoreactivity was separated into two components. Neuropeptide gamma was the most abundant peptide and its primary structure was established as Asp-Ala-Gly-Tyr-Gly-Gln-Ile-Ser-His-Lys-Arg-His-Lys-Thr-Asp-Ser- Phe-Val-Gly-Leu-Met-NH2. This sequence shows one substitution (Tyr for His4) compared with mammalian neuropeptide gamma. The second component was identical to mammalian neurokinin A. A peptide with the chromatographic properties of mammalian neuropeptide K was not identified in the extract.

Alligators and Crocodiles↗
PubMed1992

Isolation and structural characterization of peptides related to alpha- and gamma-melanocyte-stimulating hormone (MSH) from the frog brain.

Peptides that are derived from the processing of proopiomelanocortin were isolated in pure form from the brain of the frog Rana ridibunda. The primary structure of the most abundant of those peptides was established as: Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val. This amino acid sequence is identical to that of mammalian and frog pituitary alpha-melanocyte-stimulating hormone (MSH) and the peptide co-eluted with synthetic desacetyl alpha-MSH, indicating that it is COOH-terminally alpha-amidated. A second component, which exhibited a shorter retention time, co-eluted with the glycine-extended form of desacetyl alpha-MSH [ACTH(1-14)]. The primary structure of the third peptide isolated in pure form from the brain extract was established as: Lys-Tyr-Val-Met-Ser-His-Phe-Arg-Trp-Asn-Lys-Phe-NH2. This sequence corresponds to Lys-gamma 1-MSH as predicted from the nucleotide sequence of frog proopiomelanocortin. The presence of substantial amounts of desacetyl alpha-MSH and Lys-gamma 1-MSH in the frog brain supports the concept that, in amphibia, melanotropins may act as neurotransmitters and/or neuromodulators as well as hormonal peptides.

Amino Acid Sequence↗
PubMed1992

Isolation and primary structure of a potent toxin from the venom of the scorpion Centruroides sculpturatus Ewing.

A potent toxin has been purified from the venom of the scorpion Centruroides sculpturatus Ewing using the ion-exchange resin CM-Sepharose CL-6B at basic pH. The toxin, designated CsE M1, comprised 65 amino acid residues and its primary structure was established as: Lys-Glu-Gly-Tyr-Leu-Val-Asn-Ser-Tyr-Thr10-Gly-Cys-Lys-Tyr-Glu-Cys- Leu-Lys-Leu- Gly20-Asp-Asn-Asp-Tyr-Cys-Leu-Arg-Glu-Cys-Arg30-Gln-Gln-Tyr- Gly-Lys-Ser-Gly-Gly - Tyr-Cys40-Tyr-Ala-Phe-Ala-Cys-Trp-Cys-Thr-His-Leu50-Tyr-Glu- Gln-Ala-Val-Val-Trp - Pro-Leu-Pro60-Asn-Lys-Thr-Cys-Asn. CsE M1 is the most lethal protein to be identified in C. sculpturatus venom and the LD50 of the toxin, determined by subcutaneous injection into Swiss mice, is 87 micrograms/kg. CsE M1 shows strong structural similarity (92% positional identity) to the most potent beta-toxin, Css II, from the Mexican scorpion, Centruroides suffusus suffusus but is quite dissimilar to the previously characterized toxins with low potency isolated from C. sculpturatus Ewing.

Amino Acid Sequence↗
PubMed1992

Purification and biological activity of alligator bradykinin.

Incubation of plasma form the alligator (Alligator mississipiensis) with glass beads in the presence of a kininase inhibitor resulted in the activation of the kallikrein-kinin system and generation of bradykinin-like immunoreactivity. The kinin peptides were purified to homogeneity and were shown to comprise [Thr6]-bradykinin and des-Arg9[Thr6]bradykinin in the molar ratio of approximately 10:1. Bolus injections of synthetic [Thr6]bradykinin into the jugular vein of the anesthetized alligator resulted in a dose-dependent decrease in mean arterial blood pressure. The minimum dose of kinin producing a significant fall in pressure was 0.07 micrograms/kg body wt and the maximum response (25 +/- 6% fall; mean +/- SD, n = 8) was produced by a dose of 0.56 micrograms/kg body wt. The dose producing a half-maximum response was 0.19 +/- 0.08 micrograms/kg. The data indicate that alligator plasma contains all the components of the kallikrein-kinin system found in mammals and suggest that the system may be of physiological importance in the regulation of cardiovascular function in these reptiles.

Alligators and Crocodiles↗
PubMed1992

Purification and characterization of urotensin II and parvalbumin from an elasmobranch fish, Scyliorhinus canicula (common dogfish).

The caudal portion of the spinal cord of elasmobranch fish incorporates a diffuse neuroendocrine system. Using an antiserum raised against urotensin II from a teleost fish (goby) to facilitate purification, a peptide structurally related to urotensin II was isolated in pure form from an extract of neuroendocrine tissue from the spinal cord of the European common dogfish, Scyliorhinus canicula. The primary structure of the peptide was established as: Asn-Asn-Phe-Ser-Asp-Cys-Phe-Trp-Lys-Tyr-Cys-Val. The amino acid sequence was confirmed by chemical synthesis. A comparison of this sequence with those of the known teleost urotensin II peptides shows that the cyclic region of the molecule has been fully conserved between species and suggests that the presence of an acidic residue at position 5 and a hydrophobic residue at position 12 are important features for the biological activity of the peptide. The dogfish spinal cord extract also contained a high concentration of the calcium-binding protein, parvalbumin and the amino acid sequence at its NH2 terminus [residues (1-50)] was determined.

Amino Acid Sequence↗
PubMed1992

Role of peptidases in bradykinin-induced increase in vascular permeability in vivo.

The purpose of this study was to examine whether neutral endopeptidase and angiotensin I-converting enzyme, two membrane-bound metalloenzymes that are widely distributed in the microcirculation, play a role in bradykinin-induced increase in vascular permeability in the hamster cheek pouch. Changes in vascular permeability were quantified by counting the number of leaky sites and by calculating the clearance of fluorescein isothiocyanate (FITC)-dextran (molecular mass, 70,000 d) during suffusion of the cheek pouch with bradykinin. Bradykinin produced a concentration- and time-dependent increase in the number of leaky sites and clearance of FITC-dextran. The selective, active site-directed neutral endopeptidase inhibitors phosphoramidon (1.0 microM) and thiorphan (10.0 microM) and the selective angiotensin I-converting enzyme inhibitor captopril (10.0 microM) each shifted the concentration-response curve to bradykinin significantly to the left. During suffusion with bradykinin (1.0 microM) and phosphoramidon, the number of leaky sites increased significantly from 17 +/- 2 to 27 +/- 4 sites per 0.11 cm2 (mean +/- SEM, p less than 0.05), and FITC-dextran clearance increased significantly from 1.0 +/- 0.2 to 2.1 +/- 0.3 ml/sex x 10(-6).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Primary structures of the bombesin-like neuropeptides in frog brain show that bombesin is not the amphibian gastrin-releasing peptide.

Peptides displaying gastrin-releasing peptide/bombesin-like immunoreactivity were isolated in pure form from an extract of the brain of the European green frog, Rana ridibunda. The primary structure of the more abundant peptide was established as: Gly-Ser-His-Trp-Ala-Val-Gly-His-Leu-Met. NH2. This sequence shows one substitution (Ser for Asn) compared with mammalian gastrin-releasing peptide (18-27) (neuromedin C). The extract also contained gastrin-releasing peptide but bombesin was absent. The data indicate that bombesin is not the amphibian counterpart of gastrin-releasing peptide.

Amino Acid Sequence↗
PubMed1991

Primary structure and conformational analysis of peptide methionine-tyrosine, a peptide related to neuropeptide Y and peptide YY isolated from lamprey intestine.

A peptide belonging to the pancreatic-polypeptide-fold family of regulatory peptides has been isolated from the intestine of an Agnathan, the sea lamprey (Petromyzon marinus). The primary structure of the peptide (termed peptide methionine-tyrosine) was established as Met-Pro-Pro-Lys-Pro-Asp-Asn- Pro-Ser-Pro10-Asp-Ala-Ser-Pro-Glu-Leu-Ser-Lys-Tyr20-Met-Leu- Ala-Val-Arg-Asn- Tyr-Ile-Asn-Leu30-Ile-Thr-Arg-Gln-Arg-Tyr CONH2. This sequence shows stronger structural similarity with pig neuropeptide Y (64%), particularly in the COOH-terminal region, than with pig peptide tyrosine--tyrosine (61%) or with pig pancreatic polypeptide (42%). Molecular modelling and dynamic simulation, based upon sequence similarity with turkey pancreatic polypeptide, indicates that the conformations of the polyproline-helix-like region (residues 1-8) and the alpha-helical region (residues 15-30) in turkey pancreatic polypeptide are conserved in peptide methionine-tyrosine, and that non-bonded interactions between these domains have preserved the overall polypeptide fold in the molecule. The substitution of the otherwise totally conserved Gly9 residue by serine in lamprey peptide methionine-tyrosine, however, results in a preferred structure in which the conformation of the beta-turn between the two helical domains (residues 9-14) is appreciably different.

Amino Acid Sequence↗
PubMed1991

Identification of a peptide arising from the specific post-translation processing of secretogranin II.

The biological role of secrotogranin II is unknown but it has been suggested that the protein may function as a precursor of one or more biologically active neuroendocrine peptides. We have isolated a 33 amino acid-residue peptide from the brain of the frog Rana ridibunda that shows strong (82%) homology with human presecretogranin II-(182-204)-peptide. This region of secretogranin II has also been very strongly conserved in the rat and bovine proteins. Analysis of the nucleotide sequence of the mammalian secretogranin II cDNAs indicates that the peptide sequence is flanked by two Lys-Arg dibasic residue processing sites. It is proposed, therefore, that this fragment represents a specific product of the post-translational processing of secretogranin II and, by analogy with peptides derived from chromogranin A, may be important in the regulation of neurosecretion.

Amino Acid Sequence↗
PubMed1991

Substance P, neurokinin A and calcitonin gene-related peptide during development of the rat gastrointestinal tract.

Substance P, neurokinin A and calcitonin gene-related peptide (CGRP) were determined in the stomach and small intestine of rats during late foetal development and up to 35 days postnatal life. Concentrations of substance P in stomach and intestine increased from 14 gestational days to 3 days postpartum, and declined thereafter. Concentrations of neurokinin A in stomach declined from 14 days gestation over the period 3-35 postnatal days. In the intestine, concentrations of neurokinin A increased steadily from 14 days gestation to 21-35 postnatal days. Concentrations of CGRP in stomach and intestine declined from 14 days gestation to 7 postnatal days. Thereafter, concentrations of CGRP increased in both stomach and intestine. Total contents of each of the three peptides increased progressively with gestational and postnatal age in parallel with increasing stomach and intestinal weights. The results demonstrate different patterns of change in the concentrations of substance P, neurokinin A and CGRP during the dynamic phases of growth and maturation of the gastrointestinal tract in the foetal and postnatal rat.

Animals↗
PubMed1991

Structure and receptor-binding activity of insulin from a holostean fish, the bowfin (Amia calva).

The holostean fishes are the extant representatives of the primitive ray-finned fishes from which the present-day teleosts may have evolved. The primary structure of insulin from a holostean fish, the bowfin (Amia calva), was established as: A-chain: Gly-Ile-Val-Glu-Gln-Cys-Cys-Leu-Lys-Pro-Cys-Thr-Ile-Tyr-Glu-Met-Glu- Lys-Tyr-Cys-Asn B-chain: Ala-Ala-Ser-Gln-His-Leu-Cys-Gly-Ser-His-Leu-Val-Glu-Ala-Leu-Phe-Leu- Val-Cys-Gly-Glu-Ser-Gly-Phe-Phe-Tyr-Asn-Pro-Asn-Lys-Ser This amino acid sequence contains several substitutions (methionine at A16, phenylalanine at B16 and serine at B22) at sites that have been strongly conserved in other vertebrate species and that may be expected to influence biological activity. Consistent with this prediction, bowfin insulin was approx. 14-fold less potent than pig insulin in inhibiting the binding of [125I-Tyr-A14](human insulin) to transfected mouse NIH 3T3 cells expressing the human insulin receptor.

Amino Acid Sequence↗
PubMed1991

Characterization of melanotropin-release-inhibiting factor (melanostatin) from frog brain: homology with human neuropeptide Y.

A polypeptide was purified from frog brain extracts on the basis of its ability to inhibit alpha-melanotropin release from perifused frog neurointermediate lobes. Based on Edman degradation, amino acid analysis, and peptide mapping, the primary structure of this frog melanotropin-release-inhibiting factor (melanostatin) was determined to be H-Tyr-Pro-Ser-Lys-Pro-Asp-Asn-Pro-Gly-Glu-Asp-Ala-Pro-Ala-Glu-Asp-Met- Ala-Lys-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg- Tyr-NH2 . Frog melanostatin belongs to the pancreatic polypeptide/neuropeptide Y/peptide YY family, and the structure of this peptide differs from that of human neuropeptide Y by only one amino acid substitution in position 19. A synthetic replicate of frog melanostatin is coeluted with the native peptide on HPLC and is highly potent in inhibiting alpha-melanotropin secretion in vitro (IC50 = 60 nM).

Amino Acid Sequence↗
PubMed1991

Rabbit neuromedin U-25: lack of conservation of a posttranslational processing site.

The rabbit small intestine contains neuromedin U-like immunoreactivity (22 pmol/g wet tissue weight) that was resolved into a single major molecular form by reversed-phase HPLC. The primary structure of the peptide was established as: Phe-Pro-Val-Asp-Glu-Glu-Phe-Gln-Ser-Pro10-Phe-Gly-Ser-Arg-Ser-Arg- Gly-Tyr-Phe- Leu20-Phe-Arg-Pro-Arg-Asn.NH2. In rabbit neuromedin U, the Arg16-Arg17 dibasic residue processing site that is found in pig and dog neuromedin U-25 is replaced by Arg-Gly, but this potential monobasic processing site is not utilized by cleavage enzyme(s) in the intestine.

Amino Acid Sequence↗
PubMed1991

Regulatory peptide and serotonin content and brush-border enzyme activity in the rat gastrointestinal tract following neonatal treatment with capsaicin; lack of effect on epithelial markers.

The possible trophic influence of the capsaicin-sensitive extrinsic innervation of the gastrointestinal mucosa was investigated. Rats were treated neonatally with capsaicin. The gastrointestinal content of serotonin and glucagon-like immunoreactivity were used as a measure of the effect on the endocrine gut mucosa and gastrointestinal aminopeptidase and alkaline phosphatase activities were used as a measure of the effect on the gut brush-border. The gastrointestinal content of the neuropeptides substance P, VIP and CGRP were used to monitor effects on the innervation of the gut. The depletion of substance P-immunoreactivity(-IR) and calcitonin gene-related peptide(CGRP)-IR in extracts of urinary bladder and lung from the capsaicin-treated rats is evidence of the efficacy of capsaicin treatment in affecting a loss of C-fibre sensory nerves. The significant depletion of CGRP-IR measured in the stomach and duodenum of capsaicin-treated rats indicated the loss of the C-fibre sensory innervation to the gastrointestinal tract. The gastrointestinal content of VIP and substance P, which are predominantly within intrinsic gut neurones, were unaffected by capsaicin treatment. In all regions of the gastrointestinal tract of capsaicin-treated rats, the serotonin and glucagon-IR levels were not significantly different from those in controls. Similarly the levels of activity of the brush-border enzymes were not significantly effected by capsaicin treatment. This suggest the absence of any major trophic influence of capsaicin-sensitive sensory nerves on the gut endocrine mucosa and the brush border.

Alkaline Phosphatase↗
PubMed1991

Isolation and structural characterization of a molecular variant of dog pancreatic secretory trypsin inhibitor.

A rapid two-step method has been developed for the purification of pancreatic secretory trypsin inhibitor (PSTI) from pancreatic juice obtained from dogs, stimulated with secretin and the octapeptide of cholecystokinin. The PSTI was isolated in two biologically active molecular forms. Determination of amino acid compositions and NH2-terminal amino acid sequences demonstrated that the major form represented the intact 57-amino-acid residue peptide, and the minor form (comprising 5-10% of the total activity) represented des[Asn1 Asn2 Met3] PSTI. The metabolite arises from cleavage of a Met-Leu bond, and its formation may be a consequence of incomplete inhibition of chymotrypsinogen activation in the juice.

Amino Acid Sequence↗
PubMed1991

Primary structure of pancreatic polypeptide from four species of Perissodactyla (Przewalski's horse, zebra, rhino, tapir).

Pancreatic polypeptide (PP) has been purified from extracts of the pancreas of four species of odd-toed ungulates (Perissodactyla): Przewalski's horse, mountain zebra, white rhinoceros, and mountain tapir. The amino acid sequence of Przewalski's horse pancreatic polypeptide was established as Ala-Pro-Met-Glu-Pro-Val-Tyr-Pro-Gly-Asp10-Asn- Ala-Thr-Pro-Glu-Gln-Met-Ala-Gln-Tyr20-Ala-Ala-Glu-Leu-Arg-Arg-Tyr- Ile-Asn-Met30 - Leu-Thr-Arg-Pro-Arg-Tyr.NH2. Zebra PP was identical to Przewalski's horse PP, rhinoceros PP contained three substitutions relative to the horse (Ser for Ala1, Leu for Met3, and Glu for Gln16), and tapir PP contained one substitution relative to the horse (Leu for Met3). On the basis of morphological characteristics and the fossil record, the rhinocerotids are classified with the tapirids in the suborder Ceratomorpha, whereas the horse and zebra belong to a separate suborder, Hippomorpha. On the basis of structural similarity of the PP molecules, however, it would appear that the tapir is more closely related to the horse than to the rhinoceros. These observations provide a further example of the need for extreme caution when inferring taxonomic or phylogenetic relationships between species from the structures of homologous peptides.

Amino Acid Sequence↗
PubMed1991

The primary structure of glucagon-like peptide but not insulin has been conserved between the American eel, Anguilla rostrata and the European eel, Anguilla anguilla.

Insulin was isolated from the pancreas of the American eel, Anguilla rostrata, and its primary structure was established as (Formula: see text). Eel insulin contains unusual substitutions at B-21, B-22, and B-26 in the putative receptor-binding region of the molecule compared with other mammalian and fish insulins. The A-chain of insulin from the European eel contains an asparagine rather than a serine residue at position A-12. Similarly, amino acid composition data indicate the B-chain of insulin from the European eel is appreciably different from that from the American eel. The primary structure of glucagon-like peptide (GLP) from the American eel is identical to that from the European eel, Anguilla anguilla. The primary structure of the peptide was established as (Formula: see text). Fast-atom bombardment mass spectrometry demonstrated that the COOH-terminal arginyl residue is alpha-amidated. The strong evolutionary pressure to conserve the structure of GLP provides further support for the assertion that the peptide plays an important regulatory role in teleost fish.

Amino Acid Sequence↗