Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Immunoreactivity to the amphibian peptide bombesin was found in instant nonfat dry milk (ca. 0.7 ng/ml) and in the whey of whole or skim bovine milk (ca. 1.2 ng/ml) even after ultracentrifugation. The soluble immunoreactivity was associated with a peptide exhibiting the following characteristics: (i) parallel displacement in an immunoassay using an antiserum recognizing bombesin amino acid residues 5-8; (ii) separation from both gastrin-releasing peptide and amphibian bombesin by gel filtration--the approximate Mr was 3,200; (iii) denaturation in urea, reduction by dithiothreitol, and acetylation by iodoacetamide had no effect on its elution profile by gel-filtration chromatography and the aggregation of added bombesin to milk proteins or peptides was not observed; (iv) reversed-phase HPLC separated milk immunoreactivity from gastrin-releasing peptide and bombesin; (v) digestion by trypsin yielded a smaller immunoreactive peptide fragment, whereas nearly all immunoreactivity was lost by treatment with alpha-chymotrypsin; and (vi) the level of immunoreactivity was unaffected by boiling. These data show that milk is an exogenous source of bombesin-like immunoreactivity, which may account for the increase of gastric acid and gastrointestinal hormone levels after the consumption of milk.
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PMID:A bombesin immunoreactive peptide in milk. 658 13

The effect of infusion of bombesin (60 pmol/kg 20 min) on pancreatic enzymes in serum was studied in 13 normal subjects and 12 patients with pancreatic insufficiency. In normal subjects administration of bombesin induced large increases in serum trypsin (p less than 0.01), while serum total alpha-amylase and pancreatic alpha-amylase did not change and serum lipase showed only a modest rise (0.01 less than p less than 0.05). Patients with pancreatic insufficiency had significantly lower serum concentrations of all enzymes studied (p less than 0.01) and in such patients bombesin did not change the concentrations of pancreatic enzymes in serum. It is concluded that determination of the serum trypsin response to bombesin may be of help in the diagnosis of pancreatic insufficiency.
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PMID:Serum trypsin, alpha-amylase and lipase during bombesin stimulation in normal subjects and patients with pancreatic insufficiency. 660 37

We studied the effect of bombesin (9 ng/kg X min for 30 min by intravenous infusion) on serum immunoreactive trypsin in healthy subjects and in chronic pancreatitis patients. Bombesin administration caused a marked and significant increase of serum immunoreactive trypsin concentration in healthy subjects. The increase occurred in the first 15 min after the beginning of bombesin infusion and persisted for the duration of the study (2 h). In patients with chronic pancreatitis, the increase was much less pronounced. In these patients, the integrated immunoreactive trypsin response to bombesin was significantly correlated with bicarbonate, lipase, and chymotrypsin outputs into the duodenum. The response of serum immunoreactive trypsin to bombesin stimulation seems to vary according to the degree of pancreatic exocrine dysfunction and to reflect the functional capacity of acinar cell mass.
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PMID:Effect of bombesin on serum immunoreactive trypsin in healthy subjects and in patients with chronic pancreatitis. 686 57

We have developed a method to rapidly identify the antigenic determinant for an antibody using in situ proteolysis of an immobilized antigen-antibody complex followed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI/TOF). A mouse anti-bombesin monoclonal antibody was immobilized to agarose beads and then the antigen, gastrin-releasing peptide (GRP), was allowed to bind. Direct analysis of the immobilized antigen-antibody complex by MALDI/TOF is demonstrated and allows identification of ca. 1 pmol of the bound GRP. To identify the epitope, the immobilized antigen-antibody complex was subjected to proteolysis with trypsin, chymotrypsin, thermolysin, and aminopeptidase M. Following proteolysis, the part of the antigen in contact with the antibody and protected from proteolysis was identified directly by MALDI/TOF. Subsequently, the epitope was eluted from the immobilized antibody with 0.1 M glycine buffer (pH 2.3), separated by reversed-phase HPLC, and its identity confirmed by MALDI/TOF. Using this approach, the epitope for the anti-bombesin monoclonal antibody was shown to comprise the last 7-8 residues (HWAVGHLM-NH2) of GRP.
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PMID:Epitope mapping of the gastrin-releasing peptide/anti-bombesin monoclonal antibody complex by proteolysis followed by matrix-assisted laser desorption ionization mass spectrometry. 753 May 43

Prostate-specific antigen (PSA), a M(r) 34,000 serine protease, is recognized as a useful marker for the detection and prognosis of patients with prostate cancer. Although serum PSA is an excellent prognostic indicator, an increasing number of factors were found to regulate the PSA expression of prostatic cancer cells, which include androgenic steroids, the growth factors (GFs) and the extracellular matrix. The purpose of this study is to define a novel protein factor that may be responsible for regulating PSA expression by androgen-independent (AI) human prostate cancer cells. We have established a LNCaP subline (C4) from a parental LNCaP tumor grown in a castrated host. The C4 subline overexpressed PSA mRNA and protein. Serum-free conditioned medium (CM) isolated from the C4 subline is able to stimulate PSA gene expression in parental LNCaP cells in a concentration-dependent manner. This autocrine PSA-inducing activity was found to be organ specific because CMs from other fibroblast cell lines (such as bone, prostate, kidney, and lung fibroblasts) and the CMs from several prostatic carcinoma cell lines (such as parental LNCaP, PC-3, DU-145) and a bladder transitional carcinoma cell line (WH) fail to exhibit similar activity. The activity of the CM from the C4 subline cannot be substituted by GFs such as TGF-alpha, TGF-beta, bFGF, HGF, KGF, or NGF; neuropeptide (bombesin/GRP); secondary messenger analogue (dibutyryl cAMP); beta 2-adrenergic agonist (isoproterenol); or alpha 1-adrenergic agonist (phenylephrine), indicating that the factor(s) may be a novel prostate-specific autocrine factor (PSAF). Both androgen and PSAF exhibit an additive effect on up-regulating PSA gene expression, suggesting that the signal transduction pathway elicited by PSAF may differ from that mediated by the androgen receptor. Further characterization of PSAF by heat, acid, and trypsin digestion revealed that the PSAF may be a protein factor with a unique amino acid composition. These observations suggest that a novel autocrine pathway mediated by PSAF may be responsible for the overexpression of PSA mRNA and protein in a human prostatic cancer cell line. The potential clinical significance of this factor will be discussed.
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PMID:Autocrine regulation of prostate-specific antigen gene expression in a human prostatic cancer (LNCaP) subline. 768 49

Bombesin is known to induce pancreatic growth. In aged animals, reduced responsiveness of tissues of the gastrointestinal tract to a number of hormones/peptides, including bombesin, has been demonstrated, yet the effects of chronic bombesin administration on the aging pancreas is poorly understood. In the present study, groups of 4- and 20- to 22-month-old male Fischer 344 rats were infused by osmotic minipump with saline (control) or bombesin (300 ng/kg/h) for 14 days. In young rats, bombesin administration increased trypsin activity in the pancreas, which was accompanied by an increase in trypsinogen steady-state mRNA levels. However, this response to bombesin was not observed in aged rats. Bombesin also increased pancreatic glutathione peroxidase and reductase, but not superoxide dismutase activity in young rats, whereas activity of these antioxidant enzymes was not affected by bombesin in old rats. These data further support the observation that responsiveness of the pancreas to hormones is diminished with advancing age.
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PMID:Bombesin-induced changes in expression of pancreatic enzymes in young and old rats. 768 18

Characterization of bombesin binding sites in healthy human lung was performed through direct binding techniques. There was limited binding in the absence of trypsin and chymotrypsin inhibitors, suggesting important activities of both enzymes in human lung and/or increased sensitivity of the bombesin sites toward them. In human lung membranes, bombesin, gastrin releasing peptide (GRP) and GRP-preferring bombesin receptor antagonists displaced [125I-Tyr4]bombesin binding with high affinities (36-177 nM), whereas neuromedin B possessed a lower affinity of 2878 nM. [D-F5Phe6,D-Ala11]bombesin-(6-13)-methyl ester, the most active GRP-preferring bombesin antagonist as yet reported, had the highest affinity among all antagonists tested whereas neuromedin B had the lowest affinity. These data demonstrate that the bombesin binding sites in the human lung are of the GRP-preferring type.
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PMID:Gastrin releasing peptide-preferring bombesin binding sites in human lung. 788 24

Gastrin-releasing peptide (GRP) and other bombesin-like peptides (BLP) play an important role in lung development, response to injury, and carcinogenesis. However, the mRNAs from previously cloned BLP receptors are not detectable on Northern blots of normal lung. The purpose of this study was to isolate and characterize BLP binding proteins from normal mouse lung. Soluble cytoplasmic and detergent-solubilized membrane fractions were prepared from mouse lung and evaluated for specific 125I-GRP binding. Unexpectedly, not only the solubilized membrane but also the soluble cytoplasmic fractions demonstrated saturable, high-affinity, specific GRP binding activity with Kd = 1.6 nM, Bmax = 135 fmol/mg protein and Kd = 7.5 nM, Bmax = 323 fmol/mg protein, respectively. BLP binding proteins were isolated using GRP14-27 affinity chromatography and analyzed by SDS-PAGE. In each fraction, a major unique band of approximate M(r) = 70 kD was obtained and flanked by two weaker bands of approximate M(r) = 65 and 75 kD. Preincubating samples of the cytoplasmic fraction with various neuropeptides demonstrated specificity in that only incubation with GRP14-27, the bioactive portion of the molecule, blocked affinity purification of these BLP binding proteins. The BLP binding proteins isolated from the cytoplasmic fraction were purified by HPLC, digested with trypsin, and sequenced via Edman degradation. These BLP binding proteins yielded peptides with the sequences IXGIYTDGQNTPXG and RAIMVEXXSEAXXSLLTP, both of which are unique compared with the GenBank/EMBL data base.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Novel bombesin-like peptide binding proteins from lung. 811 51

The binding characteristics of histogranin (HN), an endogenous peptide first recognized for its antagonism of N-methyl-D-aspartate (NMDA) responses, were determined in membrane preparations of rat brain. [125I][Ser1]HN, a stable bioactive analog of HN, bound specifically and reversibly to a homogenous population of high-affinity sites with a Kd of 25 nM and a Bmax of 410 fmol/mg protein. The binding of [125I][Ser1]HN increased linearly with membrane protein concentration and was destroyed upon membrane pretreatment with trypsin. The binding displayed rapid association and dissociation kinetics and was blocked by peptides possessing close homology with HN in the following order: [Ser1]HN-(1-15) > HN > [Ser1]HN-(1-14) > HN-(2-15) > [Ser1]-HN-(1-10) > HN-(6-10). Unrelated peptides such as substance P, beta-endorphin, neuropeptide Y, [Met5]enkephalin, [Leu5]enkephalin, dynorphin A(1-13) and neuromedin C were inactive in competition binding assays against [125I]Ser1]HN. Ligands of the binding domains of the NMDA receptor, such as (+)3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid, (+) 5-methyl-10,11-dihydro 5H-dibenzo[a, d]cyclohepten-5,10-imine hydrogen maleate, 1-N-(2-thienyl)cyclohexylpiperidine, glycine and glutamate were also ineffective in competing for [125I][Ser1]HN binding sites. Interestingly, specific ligands for the polyamine site on the NMDA receptor, as well as the cations Mg++ and Zn++ inhibited [125I][Ser1]HN binding. The polyamine antagonist diethylenetriamine produced a noncompetitive inhibition with an IC50 (175 nM) comparable to that of HN (75 nM). The cations Zn++ and Mg++ displaced [125I][Ser1]HN binding with IC50 values of 18 and 240 microM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Characterization of [125I][Ser1]histogranin binding sites in rat brain. 822 61

Food ingestion stimulates cholecystokinin (CCK) release from the proximal intestine, but the mechanisms involved are not well understood. To investigate this effect in vivo in intact rats, plasma CCK was measured after orogastric feeding of proteins, protein hydrolysates, amino acids, glucose, and starch. Intact proteins were the only nutrients to stimulate CCK release. The possibility of direct interaction between different dietary constituents and intestinal CCK-secreting endocrine cells was then examined using a perfusion system containing isolated mucosal cells from the rat duodenojejunum. The functional validity of this system was established by demonstrating that monitor peptide and bombesin both stimulated CCK release in a dose-dependent manner. The stimulatory effect of bombesin required extracellular calcium and was not inhibited by addition of tetrodotoxin. Perifusion of proteins, protein digests, and carbohydrates did not stimulate CCK release. These results indicate that proteins stimulate CCK release postprandially via an indirect mechanism, most likely related to inhibition of intraluminal trypsin. Perifusion of dispersed mucosal cells constitutes a reproducible model to investigate hormonal and peptidergic regulation of CCK release in vitro.
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PMID:Evidence for indirect dietary regulation of cholecystokinin release in rats. 833 59


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