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)

Isolated from an Escherichia coli strain MEN-1 is a plasmid-mediated beta-lactamase that confers resistance to methoxy imino third-generation cephalosporins. The protein purified to homogeneity was digested by trypsin, chymotrypsin and endoproteinase Asp-N. Amino acid sequence determinations of the resulting peptides gave rise to the alignment of the 263 residues of the beta-lactamase. From amino acid sequence comparison MEN-1 was found to share more than 72% identity with the chromosomally mediated beta-lactamases of Klebsiella oxytoca. Therefore, MEN-1 is the first transferable extended-spectrum beta-lactamase which is not directly derived from the widespread TEMs or SHV-1 penicillinases with which it presents less than 39% identity.
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PMID:Close amino acid sequence relationship between the new plasmid-mediated extended-spectrum beta-lactamase MEN-1 and chromosomally encoded enzymes of Klebsiella oxytoca. 163 93

A novel growth factor for bone marrow derived murine mucosal type mast cells has been isolated from the conditioned medium of the Mlsa-reactive mouse Th cell line MLS-4.2. In proliferation assays this growth factor synergizes, like IL-4, with IL-3 on established mast cell lines and was therefore termed MEA: mast cell growth enhancing activity. MEA was characterized as a glycoprotein with a Mr range between 37,000 and 43,000. Apparent homogeneity was obtained by using a four-step purification scheme including cation exchange chromatography, Procion red affinity chromatography, IEF, and gel filtration. Inasmuch as MEA was N-terminally blocked during automated Edman-degradation, peptide fragments after digestion with trypsin were used for partial amino acid sequence determination. All evaluable MEA peptide fragments showed complete sequence homology to a recently purified and cloned novel T cell growth factor (P40/TCGF III), the mouse homologue of human IL-9.
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PMID:Purification of MEA, a mast cell growth-enhancing activity, to apparent homogeneity and its partial amino acid sequencing. 214 Mar 90

Growth hormone (GH)-releasing activity has been detected in extracts of carcinoid and pancreatic islet tumors from three patients with GH-secreting pituitary tumors and acromegaly. Bioactivity was demonstrated in 2 N acetic acid extracts of the tumors using dispersed rat adenohypophyseal cells in primary monolayer culture and a rat anterior pituitary perifusion system. The GH-releasing effect was dose responsive and the greatest activity was present in the pancreatic islet tumor. Small amounts of activity were also found in two other tumors (carcinoid and small cell carcinoma of lung) unassociated with GH hypersecretion. Each of the tumors contained somatostatin-like immunoreactivity but the levels did not correlate with the net biologic expression of the tumor. Sephadex G-75 gel filtration indicated the GH-releasing activity to have an apparent molecular size of slightly greater than 6,000 daltons. The GH-releasing activity was adsorbed onto DEAE-cellulose at neutral pH and low ionic strength, from which it could be eluted by increasing ionic strength. The GH-releasing activity was further purified by high pressure liquid chromatography using an acetonitrile gradient on a cyanopropyl column to yield a preparation that was active at 40 ng protein/ml. Partially purified GH-releasing activity, from which most of the bioactive somatostatin had been removed, increased GH release by pituitary monolayer cultures to five times base line. Enzymatic hydrolysis studies revealed that the GH-releasing activity was resistant to carboxypeptidase, leucine-aminopeptidase, and pyroglutamate-amino-peptidase but was destroyed by trypsin and chymotrypsin, indicating that internal lysine and/or arginine and aromatic amino acid residues are required for biologic activity and that the NH2-terminus and CO9H-terminus are either blocked or not essential. The results provide an explanation for the presence of GH-secreting tumors in some patients with the multiple endocrine neoplasia syndrome, type I, and warrant the addition of GH-releasing activity to the growing list of hormones secreted by tumors of amine precursor uptake and decarboxylation cell types.
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PMID:Partial purification and characterization of a peptide with growth hormone-releasing activity from extrapituitary tumors in patients with acromegaly. 624 40

Serratia fonticola CUV produces two isoenzymes (forms I and II) with beta-lactamase activity which were purified by a five-step procedure. The isoenzymes had identical kinetic parameters and isoelectric point (pI = 8.12). They were characterized by a specific activity towards benzylpenicillin of 1650 U/mg. The beta-lactamase hydrolyzed benzylpenicillin, amoxycillin, ureidopenicillins, first- and second-generation cephalosporins. Carboxypenicillins and isoxazolylpenicillins were hydrolyzed to a lesser extent. Towards cefotaxime and ceftriaxone (third-generation cephalosporins), the S. fonticola enzyme exhibited catalytic efficiencies much higher than those of MEN-1 and extended-spectrum TEM derivative beta-lactamases. The beta-lactamase from S. fonticola was markedly inhibited by beta-lactamase inhibitors such as clavulanic acid, sulbactam and tazobactam. The purified isoenzymes were digested by trypsin, endoproteinase Asp-N and chymotrypsin. Amino acid sequence determinations of the resulting peptides allowed the alignment of 267 amino acid residues (Swiss-Prot, accession number P 80545) for form I beta-lactamase. Form II is five residues shorter than form I at its N-terminus. From amino acid sequence comparisons, S. fonticola CUV beta-lactamase was found to share more than 69.3% identity with the chromosomally encoded beta-lactamases of Klebsiella oxytoca, Proteus vulgaris, Citrobacter diversus and the plasmid-mediated enzymes MEN-1 and Toho-1. Therefore, the oxyimino cephalosporin-hydrolyzing beta-lactamase of S. fonticola belongs to Ambler's class A. Contribution of the serine at ABL 237 in the broad-spectrum activity of these beta-lactamases is discussed.
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PMID:Characterization and amino acid sequence analysis of a new oxyimino cephalosporin-hydrolyzing class A beta-lactamase from Serratia fonticola CUV. 930 Aug 9

Medullary thyroid cancer (MTC) shares biochemical features with other neuroendocrine tumors but the particular characteristics are largely unexplored. We investigated the biochemical neuroendocrine profile of MTC and whether specific markers could be useful in follow-up. In addition to the standard tumor marker calcitonin, plasma carcino-embryonic antigen (CEA), plasma catecholamines, (platelet) serotonin, chromogranin A, tryptase, and urinary markers of catecholamine, histamine, and serotonin metabolism were prospectively determined in 46 patients with histologically proven MTC. Patients were divided according to the stage of disease: group 1, no evidence; group 2, stable disease (SD); and group 3, progressive disease (PD). Plasma dopamine was increased in the majority of the patients with SD and PD; however it did not correlate with extent of disease. Elevated plasma platelet levels of serotonin were only present in patients with multiple endocrine neoplasia 2 with SD or PD but did not differ between those groups. Histamine metabolites were elevated in 20% of patients with SD and PD. In addition to plasma calcitonin, only CEA and chromogranin A could differentiate between stable and progressive MTC. MTCs are capable of synthesizing catecholamines, serotonin, and histamine metabolites underscoring that MTCs have metabolic characteristics in common with other neuroendocrine tumors. Thus far, clinical usefulness and relevance seems limited. The most useful markers in the follow-up of MTC are plasma calcitonin and CEA.
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PMID:Biochemical markers in the follow-up of medullary thyroid cancer. 1712 44

Amyloid is a characteristic histologic feature in medullary thyroid carcinomas (MTC). We utilized a novel mass spectrometry-based proteomic analysis to determine if we could identify specific proteins associated with amyloid in MTC. We studied 9 MTC (1 multiple endocrine neoplasia type 2A, 1 familial MTC, and 7 sporadic). Laser microdissection was utilized to sample the amyloid which was then trypsin digested and evaluated by liquid chromatography electrospray tandem MS (LC-MS/MS) which identified the presence of amyloidogenic proteins in all cases of MTC. High levels of calcitonin were identified in all 9 cases of MTC. Secretogranin-1 was identified in 6 of 9 MTC. Calcitonin gene-related peptide was identified in 4 of 9 cases of MTC. LC-MS/MS proteomic analysis provides a rapid, highly specific, and sensitive method for identification of the specific type of amyloid in these endocrine tumors. This approach may allow classification of different forms of endocrine amyloid present in neuroendocrine tumors.
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PMID:Analysis of Amyloid in Medullary Thyroid Carcinoma by Mass Spectrometry-Based Proteomic Analysis. 2630 52

Menin is encoded by the MEN1 gene, which is mutated in an inherited human syndrome, multiple endocrine neoplasia type 1(MEN1). Menin is primarily nuclear protein, acting as a tumor suppressor in endocrine organs, but as an oncogenic factor in the mixed lineage leukemia, in a tissue-specific manner. Recently, the crystal structures of menin with different binding partners reveal menin as a key scaffold protein that functionally interacts with various partners to regulate gene transcription in the nucleus. However, outside the nucleus, menin also regulates multiple signaling pathways that traverse the cell surface membrane. The precise nature regarding to how menin associates with the membrane fraction is poorly understood. Here we show that a small fraction of menin associates with the cell membrane fraction likely via serine palmitoylation. Moreover, the majority of the membrane-associated menin may reside inside membrane vesicles, as menin is protected from trypsin-mediated proteolysis, but disruption of the membrane fraction using detergent abolishes the detection. Consistently, cellular staining for menin also reveals the distribution of menin in the cell membrane and the punctate-like cell organelles. Our findings suggest that part of intracellular menin associates with the cell membrane peripherally as well as resides within the membrane vesicles.
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PMID:Menin localization in cell membrane compartment. 2656 Sep 42