Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A chemical method has been established for the detection of carboxyl-terminally amidated peptides in tissue extracts. Tissue was homogenized in an acidic medium designed to solubilize peptides while precipitating high-molecular-weight protein. The homogenate supernatant was in turn subjected to reversed-phase extraction with C18 Sep-Pak cartridges. The eluates were fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC). Individual fractions were exhaustively digested with thermolysin, derivatized with phenylisothiocyanate (PITC), and then subjected to ethyl acetate extraction under basic conditions. The phenylthiocarbamyl (PTC)-amino acid amide derivatives were selectively taken up into the organic phase, while the other digestion products remained in the aqueous phase. The organic phase was analyzed by RP-HPLC on a Pico-Tag amino acid analysis column, monitoring eluates at 254 nm. PTC-amino acid amides were identified and quantitated by comparing their elution positions and peak areas, respectively, with those of standards. Their identities were confirmed by amino acid analysis, following hydrolysis with hydriodic acid. The technique was applied to extracts of bovine posterior pituitaries and a human medullary thyroid carcinoma. Vasopressin (-Leu-Gly-amide), oxytocin (-Gly-amide), Lys1 gamma 1-melanotropin (-Phe-amide), and various acetylated and non-acetylated forms of alpha-melanotropin (-Val-amide) were identified in the posterior pituitary extract. Various forms of calcitonin (-Val-Gly-Ala-Pro-amide) were detected in the tumour extract. For vasopressin and calcitonin the thermolytic digest resulted in di- and tetra-peptides, respectively, reflecting thermolytic cleavage at more favoured sites.
 ...
PMID:Use of Pico-Tag methodology in the chemical analysis of peptides with carboxyl-terminal amides. 373 29

Recent advances in peptidomics have enabled the identification of previously uncharacterized peptides. However, sequence information alone does not allow us to identify candidates for bioactive peptides. To increase an opportunity to discover bioactive peptides, we have focused on C-terminal amidation, a post-translational modification shared by many bioactive peptides. We analyzed peptides secreted from human medullary thyroid carcinoma TT cells that produce amidated peptides, and we identified two novel amidated peptides, designated neuroendocrine regulatory peptide (NERP)-1 and NERP-2. NERPs are derived from distinct regions of the neurosecretory protein that was originally identified as a product of a nerve growth factor-responsive gene in PC12 cells. Mass spectrometric analysis of the immunoprecipitate using specific antibodies as well as reversed phase-high performance liquid chromatography coupled with radioimmunoassay analysis of brain extract demonstrated the endogenous presence of NERP-1 and NERP-2 in the rat. NERPs are abundant in the paraventricular and supraoptic nuclei of the rat hypothalamus and colocalized frequently with vasopressin but rarely with oxytocin. NERPs dose-dependently suppressed vasopressin release induced by intracerebroventricular injection of hypertonic NaCl or angiotensin II in vivo. NERPs also suppressed basal and angiotensin II-induced vasopressin secretion from hypothalamic explants in vitro. Bioactivity of NERPs required C-terminal amidation. Anti-NERP IgGs canceled plasma vasopressin reduction in response to water loading, indicating that NERPs could be potent endogenous suppressors of vasopressin release. These findings suggest that NERPs are novel modulators in body fluid homeostasis.
 ...
PMID:Peptidomic identification and biological validation of neuroendocrine regulatory peptide-1 and -2. 1760 9