Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sera from patients with a variety of cancers, including solid carcinomas, leukemias, and lymphomas, contain a ca. 33.5-kDa protein absent from sera of healthy volunteers or patients not diagnosed as having cancer. The protein exhibits an NADH oxidase activity inhibited by 8-methyl-N-vanillyl-6-noneamide (capsaicin). The activity and the protein are resistant to digestion by proteases (trypsin, chymotrypsin, proteinase K, subtilisin) and to heat. Following protease digestion to reduce the content of major serum proteins, the 33.5-kDa protein could be detected on Western blots of SDS-PAGE transferred to nitrocellulose membranes using polyclonal antisera to a corresponding partially purified 33.5-kDa protein shed into culture media conditioned by growth of HeLa cells. No corresponding protein was seen with control sera. The findings confirm the capsaicin-inhibited NADH oxidase activity of cancer sera as a circulating marker potentially specific to sera of cancer patients and identify a ca. 33.5-kDa protein resistant to proteases and heat as the source of the circulating capsaicin-inhibited NADH oxidase activity.
 ...
PMID:A 33.5-kDa heat- and protease-resistant NADH oxidase inhibited by capsaicin from sera of cancer patients. 918 12

It has been shown that treatment of bovine mitochondrial complex I (NADH-ubiquinone oxidoreductase) with NADH or NADPH, but not with NAD or NADP, increases the susceptibility of a number of subunits to tryptic degradation. This increased susceptibility involved subunits that contain electron carriers, such as FMN and iron-sulfur clusters, as well as subunits that lack electron carriers. Results shown elsewhere on changes in the cross-linking pattern of complex I subunits when the enzyme was pretreated with NADH or NADPH (Belogrudov, G., and Hatefi, Y. (1994) Biochemistry 33, 4571-4576) also indicated that complex I undergoes extensive conformation changes when reduced by substrate. Furthermore, we had previously shown that in submitochondrial particles the affinity of complex I for NAD increases by >/=20-fold in electron transfer from succinate to NAD when the particles are energized by ATP hydrolysis. Together, these results suggest that energy coupling in complex I may involve protein conformation changes as a key step. In addition, it has been shown here that treatment of complex I with trypsin in the presence of NADPH, but not NADH or NAD(P), produced from the 39-kDa subunit a 33-kDa degradation product that resisted further hydrolysis. Like the 39-kDa subunit, the 33-kDa product bound to a NADP-agarose affinity column, and could be eluted with a buffer containing NADPH. It is possible that together with the acyl carrier protein of complex I the NADP(H)-binding 39-kDa subunit is involved in intramitochondrial fatty acid synthesis.
 ...
PMID:Mitochondrial NADH-ubiquinone oxidoreductase (Complex I). Effect of substrates on the fragmentation of subunits by trypsin. 952 11

The NADH oxidase of Amphibacillus xylanus shows high NADH-peroxide reductase activity for hydrogen peroxide and alkyl hydroperoxides in the presence of a 22-kDa disulfide-containing protein component (Y. Niimura, L. B. Poole, and V. Massey, J. Biol.Chem. 270, 25645-25650, 1995). It was found that the membrane-bound NADH dehydrogenase of an alkaliphilic Bacillus (YN-1) involved in the respiratory chain also exhibits reductase activity for hydrogen peroxide and cumene hydroperoxide in the presence of the 22-kDa component from Amphibacillus xylanus. Vmax values for these substrates were as high as those of the NADH oxidase of A. xylanus. Although the 38-kDa protein produced by trypsin treatment of NADH dehydrogenase retains NADH dehydrogenase activity, it exhibited no peroxide reductase activity in the presence of the 22-kDa component from A. xylanus. The NADH dehydrogenase of YN-1 might not only catalyze electron flow from NADH to the respiratory chain, but also function for scavenging peroxide.
 ...
PMID:Peroxide reductase activity of NADH dehydrogenase of an alkaliphilic Bacillus in the presence of a 22-kDa protein component from Amphibacillus xylanus. 964 49

The alimentary tocopherol deficiency is accompanied by decreased hydroxylase, demethylase, NADH- and NADPH-reductase, aldehyde dehydrogenase, arylesterase and glutathione reductase activity in rat's liver. It decreased the reduced glutathione and increased it's oxidized form concentration in the tocopherol deficient animals. The stability of microsomal membrane is decreased to solubilizing action of deoxycholate and trypsin. This changes, possibly, caused elevation of alteration of function enzyme's and microsomal membrane after nitrosodimethylamine (NDMA) administration in deficient rats. The 7-days injection of tocopherol (20 and 100 mg/kg), dibunol (80 mg/kg), sodium selenite (30 mkg/kg) increased aldehyde dehydrogenase, esterase, glutathione-dependent enzymes activity and increased of reduced glutathione concentration in liver, suppressed lipid peroxidation and increased survival rats after lethal dose carcinogen treatment. Supplementation of tocopherol decreased harmful action of nitrosodimethylamine on microsomal membrane and enzymes activity.
 ...
PMID:[Effect of tocopherol deficiency and additional administration of tocopherol, dibunol and disodium selenite on enzyme activity in rat liver, which take part in the biotransformation of nitrosodimethylamine]. 984 11

Alpha1 Protease inhibitor (alpha1PI) modulates serine protease activity in the lung. Reactive oxygen species inactivate alpha1PI, and this process has been implicated in the pathogenesis of a variety of forms of lung injury. An imbalance of protease-antiprotease activity is also detected in the airways of patients with cystic fibrosis-associated lung disease who are infected with Pseudomonas aeruginosa. P. aeruginosa secretes pyocyanin, which, through its ability to redox cycle, induces cells to generate reactive oxygen species. We tested the hypothesis that redox cycling of pyocyanin could lead to inactivation of alpha1PI. When alpha1PI was exposed to NADH and pyocyanin, a combination that results in superoxide production, alpha1PI lost its ability to form an inhibitory complex with both porcine pancreatic elastase (PPE) and trypsin. Similarly, addition of pyocyanin to cultures of human airway epithelial cells to which alpha1PI was also added resulted in a loss of the ability of alpha1PI to form a complex with PPE or trypsin. Neither superoxide dismutase, catalase, nor dimethylthiourea nor depletion of the media of O2 to prevent formation of reactive oxygen species blocked pyocyanin-mediated inactivation of alpha1PI. These data raise the possibility that a direct interaction between reduced pyocyanin and alpha1PI is involved in the process. Consistent with this possibility, pretreatment of alpha1PI with the reducing agent beta-mercaptoethanol also inhibited binding of trypsin to alpha1PI. These data suggest that pyocyanin could contribute to lung injury in the P. aeruginosa-infected airway of cystic fibrosis patients by decreasing the ability of alpha1PI to control the local activity of serine proteases.
 ...
PMID:The Pseudomonas aeruginosa secretory product pyocyanin inactivates alpha1 protease inhibitor: implications for the pathogenesis of cystic fibrosis lung disease. 1002 62

Creatine kinase (CK) will autoincorporate radiolabel from [gamma32P]ATP and has thus been reported to be autophosphorylated. Also, in contrast to normal brain enzyme, CK in Alzheimer-diseased brain homogenate shows greatly decreased activity, abolished photolabeling with [32P]8N3ATP, and no detectable autoincorporation of radiolabel by [gamma32P]ATP. Surprisingly, our studies with both human brain and purified CK showed that [alpha32P]ATP, [gamma32P]ATP, [alpha32P]ADP, [2,8H3]ATP, [gamma32P]2',3'-O-(2,4, 6-trinitrophenyl)-ATP, and [gamma32P]benzophenone-gammaATP all autoincorporate radiolabel into CK with good efficiency. This demonstrates that the gamma-phosphate and the 2' and 3' hydroxyls are not involved in the covalent linkage and that all three phosphates, the ribose and base of the ATP molecule are retained upon autoincorporation (nucleotidylation). Treatment with NaIO3 to break the 2'-3' linkage effected total loss of radiolabel indicating that nucleotidylation resulted in opening of the ribose ring at the C1' position. Nucleotidylation with increasing [alpha32P]ATP at 37 degrees C gives an approximate k0.5 of 125 microM and saturates at 340 microM nucleotide. Modification of 8-10% of the copy numbers occurs at saturation, and CK activity is inhibited to approximately the same degree. Low micromolar levels of native substrates such as ADP, ATP, and phosphocreatine substantially reduce [alpha32P]ATP nucleotidylation. In contrast, AMP, GTP, GMP, NADH, and creatine did not effectively reduce nucleotidylation. When [alpha32P]ATP-nucleotidylated or [alpha32P]8N3ATP-photolabeled CK is treated with trypsin a single, identical radiolabeled peptide (V279-R291) is generated that comigrates on reverse phase HPLC and Tris-tricine electrophoresis. Nucleotidylation into this peptide was prevented 86% by the presence of ATP. We conclude that CK is nucleotidylated within the active site by modification at the C1'position and that autophosphorylation of this enzyme does not occur.
 ...
PMID:ATP nucleotidylation of creatine kinase. 1038 96

Reduction of extracellular ferricyanide by intact cells reflects the activity of an as yet unidentified trans-plasma membrane oxidoreductase. In human erythrocytes, this activity was found to be limited by the ability of the cells to recycle intracellular ascorbic acid, its primary trans-membrane electron donor. Ascorbate-dependent ferricyanide reduction by erythrocytes was partially inhibited by reaction of one or more cell-surface sulfhydryls with p-chloromercuribenzene sulfonic acid, an effect that persisted in resealed ghosts prepared from such treated cells. However, treatment of intact cells with the sulfhydryl reagent had no effect on NADH-dependent ferricyanide or ferricytochrome c reductase activities of open ghosts prepared from treated cells. When cytosol-free ghosts were resealed to contain trypsin or pronase, ascorbate-dependent reduction of extravesicular ferricyanide was doubled, whereas NADH-dependent ferricyanide and ferricytochrome c reduction were decreased by proteolytic digestion. The trans-membrane ascorbate-dependent activity was also found to be inhibited by reaction of sulfhydryls on its cytoplasmic face. These results show that the trans-membrane ferricyanide oxidoreductase is limited by the ability of erythrocytes to recycle intracellular ascorbate, that it does not involve the endofacial NADH-dependent cytochrome b(5) reductase system, and that it is a trans-membrane protein that contains sensitive sulfhydryl groups on both membrane faces.
 ...
PMID:Ascorbate-dependent electron transfer across the human erythrocyte membrane. 1056 68

Incubation of two types of glutamate dehydrogenase (GDH) isoproteins from bovine brain with o-phthalaldehyde resulted in a time-dependent loss of enzyme activity. The inactivation was partially prevented by preincubation of the GDH isoproteins with 2-oxoglutarate or NADH. Spectrophotometric studies indicated that the inactivation of GDH isoproteins with o-phthalaldehyde resulted in isoindole derivatives characterized by typical fluorescence emission spectra with a stoichiometry of one isoindole derivative per molecule of enzyme subunit. There were no differences between the two GDH isoproteins in sensitivities to inactivation by o-phthalaldehyde indicating that the microenvironmental structures of the GDH isoproteins are very similar to each other. Tryptic peptides of the isoproteins, modified with and without protection, identified a selective modification of one lysine as in the region containing the sequence L-Q-H-G-S-I-L-G-F-P-X-A-K for both GDH isoproteins. The symbol X indicates a position for which no phenylthiohydantoin-amino acid could be assigned. The missing residue, however, can be designated as an o-phthalaldehyde-labeled lysine since the sequences including the lysine residue in question have a complete identity with those of the other mammalian GDHs. Also, trypsin was unable to cleave the labeled peptide at this site. Both amino acid sequencing and compositional analysis identified Lys-306 as the site of o-phthalaldehyde binding within the brain GDH isoproteins.
 ...
PMID:Identification of lysine residue involved in inactivation of brain glutamate dehydrogenase isoproteins by o-phthalaldehyde. 1060 7

Recessive congenital methemoglobinemia due to nicotinamide adenine dinucleotide (NADH)-cytochrome b5 reductase (b5R) deficiency is classified into 2 clinical types: type 1 (erythrocyte type) and type 2 (generalized type). We found a Chinese family with type 1 recessive congenital methemoglobinemia, the patients from which were diagnosed according to clinical symptoms and b5R enzyme activity in the blood cells. To learn the molecular basis of type 1 recessive congenital methemoglobinemia in this Chinese family, we isolated total RNA from the peripheral leukocytes of the propositus and b5R complementary DNA (cDNA) by reverse transcription- polymerase chain reaction (RT-PCR). The coding region of the b5R cDNA was analyzed by sequencing the cloned PCR products. The results showed that the propositus was homozygous for a G-->A transition at codon 203 in exon 7, changing a cysteine to a tyrosine (Cys203Tyr). To characterize the mutant enzyme, both glutathione S-transferase (GST)-fused wild-type b5R and GST-fused mutant Cys203Tyr b5R were expressed in Escherichia coli and affinity purified. The results showed that the catalytic activity of the enzyme was not much affected by this amino acid substitution, but the mutant enzyme exhibited decreased heat stability and increased susceptibility to trypsin. These properties of the mutant enzyme would account for the restricted b5R deficiency and mild clinical manifestations of these type 1 patients. The finding of this novel mutation makes codon 203 the only position within the b5R gene at which more than 1 mutation has been found.
 ...
PMID:A novel mutation in the NADH-cytochrome b5 reductase gene of a Chinese patient with recessive congenital methemoglobinemia. 1080 96

Nicotinamide nucleotide transhydrogenase from Escherichia coli is composed of two subunits, the alpha and the beta subunits, each of which contains a hydrophilic domain, domain I and III, respectively, as well as several transmembrane helices, collectively denoted domain II. The interactions between domain I from Rhodospirillum rubrum (rrI) and the intact or the protease-treated enzyme from E. coli was investigated using the separately expressed and purified domain I from R. rubrum, and His-tagged intact and trypsin-treated E. coli transhydrogenase. Despite harsh treatments with, e.g. detergents and denaturing agents, the alpha and beta subunits remained tightly associated. A monoclonal antibody directed towards the alpha subunit was strongly inhibitory, an effect that was relieved by added rrI. In addition, rrI also reactivated the trypsin-digested E. coli enzyme in which domain I had been partly removed. This suggests that the hydrophilic domains I and III are not in permanent contact but are mobile during catalysis while being anchored to domain II. Replacement of domain I of intact, as well as trypsin-digested, E. coli transhydrogenase with rrI resulted in a markedly different pH dependence of the cyclic reduction of 3-acetyl-pyridine-NAD+ by NADH in the presence of NADP(H), suggesting that the protonation of one or more protonable groups in domain I is controlling this reaction. The reverse reaction and proton pumping showed a less pronounced change in pH dependence, demonstrating the regulatory role of domain II in these reactions.
 ...
PMID:Interactions between the soluble domain I of nicotinamide nucleotide transhydrogenase from Rhodospirillum rubrum and transhydrogenase from Escherichia coli. Effects on catalytic and H+-pumping activities. 1082 14


<< Previous 1 2 3 4 5 6 7 8 9 10