Imidazole C-2 hydrogen/deuterium exchange reaction at histidine for probing protein structure and function with matrix-assisted laser desorption ionization mass spectrometry.

We present a mass spectrometric method for analyzing protein structure and function, based on the imidazole C-2 or histidine C hydrogen/deuterium (H/D) exchange reaction, which is intrinsically second order with respect to the concentrations of the imidazolium cation and OD in DO. The second-order rate constant () of this reaction was calculated from the pH-dependency of the pseudo-first-order rate constant () obtained from the change of average mass Δ (0 ≤ Δ < 1) of a peptide fragment containing a defined histidine residue at incubation time () such that = − [ln(1−Δ)]/. We preferred using rather than because (maximal value of ) was empirically related to p as illustrated with a Brønsted plot: ( is an arbitrary constant), so that we could analyze the effect of structure on the H/D-exchange rate in terms of representing the deviation of from .

Effects of adrenomedullin on acute ischaemia-induced collateral development and mobilization of bone-marrow-derived cells.

Adrenomedullin exerts not only vasodilatory effects, but also angiogenic effects. In the present study, we investigated the effects of adrenomedullin on collateral formation and circulating bone-marrow-derived cells after acute tissue ischaemia. Bone marrow of 8-10-week-old female C57BL/6J mice was replaced with that from GFP (green fluorescent protein) transgenic mice (GFP mice).

Bone morphogenetic protein-3 family members and their biological functions.

Bone morphogenetic protein-3 and 3b (BMP-3 and BMP-3b) together represent a unique subgroup of the BMP family. BMP-3b shares 82% amino acid identity with BMP-3 in the mature region (ligand domain), but only 37% in the pro-region (pro-domain). In osteoblasts, BMP-3 and 3b have similar antagonistic activity against BMP-2, but they are differentially regulated.

Coordination of BMP-3b and cerberus is required for head formation of Xenopus embryos.

Bone morphogenetic proteins (BMPs) and their antagonists are involved in the axial patterning of vertebrate embryos. We report that both BMP-3b and BMP-3 dorsalize Xenopus embryos, but act as dissimilar antagonists within the BMP family. BMP-3b injected into Xenopus embryos triggered secondary head formation in an autonomous manner, whereas BMP-3 induced aberrant tail formation.

Adrenomedullin augments collateral development in response to acute ischemia.

Expression of adrenomedullin, discovered as a vasodilatory peptide, is markedly up-regulated under pathological conditions such as tissue ischemia and inflammation, which are associated with neovascularization. Here, we tested the hypothesis that overly expressed adrenomedullin may augment collateral flow to ischemic tissues. We induced hindlimb ischemia in wild-type mice and injected a naked plasmid expressing human adrenomedullin or an empty vector into the ischemic muscle, followed by in vivo electroporation.

Endothelial responses of the aorta from adrenomedullin transgenic mice and knockout mice.

Adrenomedullin (AM) is a potent vascular wall-derived vasorelaxing peptide which induces the release of nitric oxide (NO). To explore the role of endogenous AM in vascular function, we examined the effects of acetylcholine (ACh), AM, and AM receptor antagonists [AM (22-52), and calcitonin gene-related peptide (CGRP) (8-37)] on the isometric tension of aortic rings isolated from AM transgenic (TG) and knockout (KO) mice and wild type littermates (WT). ACh and AM caused a dose-dependent reduction of the isometric tension of aortic rings, but the degree of vasodilatation was smaller in TG than in KO or WT (% delta tension [10(-6) mol/l ACh]: KO -69 +/- 10%, WT -39 +/- 8%, TG -29 +/- 1%, p < 0.

Somatostatin suppresses ghrelin secretion from the rat stomach.

Ghrelin is an acylated peptide that stimulates food intake and the secretion of growth hormone. While ghrelin is predominantly synthesized in a subset of endocrine cells in the oxyntic gland of the human and rat stomach, the mechanism regulating ghrelin secretion remains unknown. Somatostatin, a peptide produced in the gastric oxyntic mucosa, is known to suppress secretion of several gastrointestinal peptides in a paracrine fashion.

Calcitonin receptor-stimulating peptide, a new member of the calcitonin gene-related peptide family. Its isolation from porcine brain, structure, tissue distribution, and biological activity.

We isolated a novel biologically active peptide, designated calcitonin receptor-stimulating peptide (CRSP), from the acid extract of the porcine brain by monitoring cAMP production in the porcine kidney cell line LLC-PK(1). Determination of the amino acid sequence and cDNA analysis encoding a CRSP precursor showed that this peptide has approximately 60% identity in the amino acid sequence with human calcitonin gene-related peptide type-alpha (alphaCGRP), type-beta (betaCGRP), and porcine CGRP. Northern blot analysis and radioimmunoassay demonstrated that CRSP is expressed mainly in the thyroid gland and the central nervous system, in which the calcitonin receptor was abundantly expressed.

The effect of pituitary adenylate cyclase activating polypeptide on cultured rat cardiocytes as a cardioprotective factor.

In the cardiovascular system, pituitary adenylate cyclase activating polypeptide (PACAP) exhibits not only vasodilation but also positive inotropic action by increasing cardiac output. Then the effect of PACAP in cultured cardiovascular cells was examined. In neonatal rat myocytes, PACAP evoked concentration-dependent increase in intracellular cyclic AMP content more potently than vasoactive intestinal polypeptide (VIP).

The role of the gastric afferent vagal nerve in ghrelin-induced feeding and growth hormone secretion in rats.

Background & Aims: Visceral sensory information is transmitted to the brain through the afferent vagus nerve. Ghrelin, a peptide primarily produced in the stomach, stimulates both feeding and growth hormone (GH) secretion. How stomach-derived ghrelin exerts these central actions is still unknown.

Role of endogenous adrenomedullin in the regulation of vascular tone and ischemic renal injury: studies on transgenic/knockout mice of adrenomedullin gene.

Adrenomedullin (AM) is a potent depressor peptide whose vascular action is suggested to involve nitric oxide (NO) release. To explore the role of endogenous AM in vascular and renal function, we examined the effects of acetylcholine (ACh), AM, and AM receptor antagonists AM(22-52) and CGRP(8-37) on the renal perfusion pressure (RPP) of kidneys isolated from AM transgenic (TG)/heterozygote knockout (KO) mice and wild-type littermates (WT). Furthermore, we evaluated the renal function and histology 24 hours after bilateral renal artery clamp for 45 minutes in TG, KO, and WT mice.

Possible involvement of oxidative stress in hypoxia-induced adrenomedullin secretion in cultured rat cardiomyocytes.

Although hypoxia induces adrenomedullin gene expression in cultured rat cardiac myocytes, it is still unknown whether oxidative stress is involved in the hypoxia-induced adrenomedullin production. We investigated whether oxidative stress might participate in hypoxia-induced adrenomedullin secretion and whether adrenomedullin might have a protective effect on damaged myocytes. Hypoxia increased adrenomedullin secretion and its gene expression in cardiac myocytes, but not in nonmyocytes.

Plasma atrial natriuretic peptide concentration inversely correlates with left atrial collagen volume fraction in patients with atrial fibrillation: plasma ANP as a possible biochemical marker to predict the outcome of the maze procedure.

Objectives: We hypothesized that the plasma atrial natriuretic peptide (ANP) level reflects atrial degenerative change and may predict the outcome of the maze procedure.

Background: Although a larger preoperative left atrial dimension and longer duration of atrial fibrillation (AF) have been reported in patients with persistent AF than in those with sinus rhythm (SR), these individual factors were not enough to predict the outcome of the maze procedure.

Methods: Preoperative plasma ANP levels were measured in consecutive 62 patients who underwent the Kosakai's modified maze procedure.

Ghrelin is present in pancreatic alpha-cells of humans and rats and stimulates insulin secretion.

Ghrelin, a novel growth hormone-releasing peptide isolated from human and rat stomach, is a 28-amino acid peptide with a posttranslational acylation modification that is indispensable for stimulating growth hormone secretion by increasing intracellular Ca(2+) concentration. It also functions in the regulation of feeding behavior, energy metabolism, and gastric acid secretion and motility. Using two different antibodies against the NH(2)- and COOH-terminal regions of ghrelin, we studied its localization in human and rat pancreas by immunohistochemistry.