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

---

Query: EC:3.4.25.1 (proteasome)
28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A multicatalytic proteinase from rat skeletal muscle contains active site(s) catalysing the degradation of benzoyl-Val-Gly-Arg 4-methyl-7-coumarylamide, succinyl-Ala-Ala-Phe 4-methylcoumarylamide and [14C]methylcasein as well as benzyloxy-carbonyl-Leu-Leu-Glu 2-naphthylamide. These activities are 7-14-fold activated by 1 mM-sodium dodecyl sulphate. The activation leads to a higher susceptibility to the proteinase inhibitor chymostatin and to a lower ability to be inhibited and precipitated by antibodies raised against the non-activated enzyme. Since no changes in Mr or subunit composition were observed in the SDS-activated form, some conformational changes seem to occur during the activation step. More pronounced activation was observed in the presence of physiological concentrations of fatty acids; oleic acid at 100 microM concentrations stimulated the proteinase about 50-fold. In contrast with the non-activated proteinase, the activated enzyme considerably degrades muscle cytoplasmic proteins in vitro. Thus it is not unlikely that, in vivo, potential activators such as fatty acids can induce the multicatalytic proteinase to participate in muscle protein breakdown.
...
PMID:Activation of the multicatalytic proteinase from rat skeletal muscle by fatty acids or sodium dodecyl sulphate. 389 Aug 40

Two forms of a neutral protease that catalyzed the hydrolysis of succinyl-Leu-Leu-Val-Tyr-MCA were isolated from porcine skeletal muscle cytosol by fractionation on DEAE-cellulose, hydroxyapatite and Sephadex G-100. The native enzyme had a molecular mass of above 1000 kDa. Peak A, which was eluted from hydroxyapatite at 50 mM phosphate, was activated 37-fold by the detergent, SDS, while peak B which was eluted at 150 mM phosphate, was activated only 2-fold. After dialysis against water, the B form showed restored ability to be activated by SDS (9.6-fold with 0.04% SDS). The activated peak B was extremely sensitive to divalent and monovalent cations such as Ca2+, Mg2+, Na+, K+ and NH+4 as well as protease inhibitors such as leupeptin, chymostatin and DFP. These results suggest that these proteases are generally latent in the cells and may be regulated by changes in the concentrations of cations in the cytosol. We call this new type of protease, ingensin.
...
PMID:Isolation of two forms of the high-molecular-mass serine protease, ingensin, from porcine skeletal muscle. 389 52

The present study was designed to examine the effect of Pseudomonas aeruginosa alkaline protease and elastase on human polymorphonuclear leukocyte chemiluminescence. Both a luminol-enhanced and a nonenhanced chemiluminescence system using opsonized zymosan were utilized. It was found that alkaline protease and elastase at concentrations of 25 micrograms/ml strongly inhibited luminol-enhanced myeloperoxidase-mediated chemiluminescence, whereas inhibition of the nonenhanced chemiluminescence response was about 50%. In an attempt to determine the mechanism of inhibition of neutrophil chemiluminescence by these proteases, we examined the effect of various inhibitors of neutrophil oxidative metabolism on chemiluminescence, namely, superoxide dismutase, sodium azide, and catalase. It was shown that the pattern of inhibition of chemiluminescence by alkaline protease and elastase was similar to that of sodium azide, inhibitor of myeloperoxidase. The present study demonstrates that alkaline protease and elastase, extracellular products of P. aeruginosa, are capable of inhibiting myeloperoxidase-mediated chemiluminescence, one of the major antimicrobial systems of polymorphonuclear leukocytes. These findings provide further evidence for the role of P. aeruginosa exoproteases as virulence factors in the pathogenesis of infections caused by this microorganism.
...
PMID:Pseudomonas aeruginosa exoproteases inhibit human neutrophil chemiluminescence. 632 28

The effect on the electrolyte balance of a dopaminergic agonist (bromocriptine) and an antagonist (metoclopramide) and their effect on renal aldosterone and kallikrein excretion were investigated. Ten normotensive Wistar rats and ten spontaneously hypertensive rats (SHR-Wistar Kioto) were treated with BCR (4 mg/Kg weight b.i.d.) for 4 days; after a week of pharmacological wash-out they received MCP (0,5 mg/Kg weight b.i.d.) for 4 days. Before and after treatment and at the 2nd and 4th day of each treatment diuresis, urinary excretion of aldosterone, kallikrein, sodium, potassium and proteins were measured. During the 24-hour urine collections the rats were kept in separate metabolic cages with free access to food and water. Kallikrein urinary excretion was lower in SHR than in normotensive rats under basal conditions (p 0.05); urinary sodium, potassium, proteins and sodium/potassium rate were also reduced in SHR. After treatment with bromocriptine a further reduction in urinary kallikrein excretion was observed in SHR. After MCP all the parameters were unchanged both in normotensive rats and in SHR, but SHR showed a significant correlation between aldosterone and kallikrein excretion (p less than 0,001); in this condition it seems that in SHR the control exerted by aldosterone on kallikrein excretion is greater than the one exerted by dopamine. It may indicate a defect of the natriuretic and vasodilator dopaminergic system in spontaneously hypertensive rats.
...
PMID:[The effect of dopaminergic stimulation and inhibition on the urinary excretion of aldosterone and kallikrein in spontaneously hypertensive rats]. 655 80

Two-dimensional analysis of tryptic peptides from [35S]methionine-labeled methyl-accepting chemotaxis proteins, MCP I and MCP II, demonstrates a high degree of homology between the two proteins. After the methylation sites were labeled with S-adenosyl-L-methyl-3H]methionine, peptides of three distinct migrations in each protein were found to carry a methyl group. These multiple methylations appear to be responsible in part for the observed multiple banding patterns on sodium dodecyl sulfate/polyacrylamide slab gels.
...
PMID:Structural studies of methyl-accepting chemotaxis proteins of Escherichia coli: evidence for multiple methylation sites. 699 98

It has previously been demonstrated in our laboratory that patients with pseudohypoparathyroidism (PsHP) have impaired PRL responses to TRH and chlorpromazine. We have also observed that these patients have low basal plasma renin activity (PRA) and decreased aldosterone responses to upright posture and isometric handgrip exercise. Since inhibitory dopaminergic modulation of PRL and aldosterone is well established, we have examined whether PsHP is associated with altered dopaminergic inhibition of PRL and aldosterone secretion. To investigate this possibility, we compared the plasma PRL, aldosterone, and PRA responses to the dopamine antagonist metoclopramide (MCP; 10 mg iv) in seven normocalcemic PsHP patients and twelve normal controls. These patients were on no medications except calcium and vitamin D for 2 weeks; they were maintained on a diet containing 50 meq of sodium and 80 meq of potassium for 5 days. Although basal PRL levels were similar in the two groups of subjects, the maximal incremental PRL response in PsHP patients (38.7 +/- 12.6 ng/ml) was less (P less than 0.01) than in normal subjects (61.6 +/- 9.6 ng/ml). Basal supine plasma aldosterone was less (P less than 0.01) in PsHP patients (8.0 +/- 1.1 ng/dl) than in normal subjects (13.4 +/- 2.1 ng/dl). Maximum incremental aldosterone response to MCP (8.7 +/- 1.9 ng/dl) in PsHP patients was also less (P less than 0.01) than in normal subjects (13.4 +/- 2.1 ng/dl). Basal supine PRA was lower (P less than 0.05) in PsHP patients (1.3 +/- 0.3 ng/ml.h) than in normal subjects (2.8 +/- 0.4 ng/ml.h). However, the PRA responses to MCP were similar in both groups. Tonic dopaminergic inhibition of PRL and aldosterone secretion, but not renin secretion, appears to be less pronounced in PsHP patients. This is the first disease state in which reduced aldosterone responses to dopamine antoganism have been observed. Decreased PRL and aldosterone responses to MCP may reflect decreased ambient dopamine levels and/or a reduction in dopamine receptor number or binding affinity.
...
PMID:Altered dopaminergic modulation of prolactin and aldosterone secretion in pseudohypoparathyroidism. 701 87

High-alkaline protease (HAP) has been entrapped in Manugel DMB (an alginate gel) and assayed with two sizes and types of substrates: neutral protein casein and synthetic chromogenic tripeptide substrate, Z-Gly-Pro-Cit-PNA. Increasing the concentration of calcium chloride used for capsule formation decreased the measured enzyme activity with both substrates. Capsules were found to be stable in water for long periods of time, but they dissolved in both phosphate and carbonate-bicarbonate buffers. The pH vs activity profiles of encapsulated enzyme showed pH optima between 10 and 11 with both substrates. The calcium alginate matrix surrounding the enzyme was quite effective in stabilizing the enzyme at 20-25 degrees C and even more so at 4 degrees C. Enzyme stability at 50 degrees C was quite impressive, some enzyme activity being evident even after remaining for 1 wk at this temperature in water. Increasing concentrations of sodium dodecyl sulfate (SDS) were also found to inhibit the protease progressively, whereas a polyhexamethylene biguanidium chloride (PHMBH+Cl-) and SDS:PHMBH+Cl- combination showed the opposite effect. Optical microscopy, especially polarized light microscopy, provided a sensitive physical means of ascertaining some of the structural properties (sphericity, disorganization or organization, distinct layer enveloping the capsules, intensity of the maltese cross) of the capsules with and without enzyme before and after different chemical treatments and the presence or absence of the substrate.
...
PMID:High-alkaline protease from Bacillus PB92 entrapped in calcium alginate gel. Physicochemical and microscopic studies. 749 34

We have identified and characterized a specific nuclease activity to be tightly associated with proteasomes. Using tobacco mosaic virus RNA (TMV-RNA) as substrate to analyze and quantify the cleavage reaction, we supply several lines of evidence that this nuclease activity is an integral part of proteasomes. Thus, RNase activity was coincident with the elution profiles of proteasomes at each stage of purification. Proteasomal nuclease activity was resistant to strong dissociation conditions using 480 mM KCl, 0.5% sodium lauroylsarcosinate, and 6 M urea. This nuclease activity remained associated with an urea-resistant subcomplex of the proteasome comprising a specific set of proteins. Finally the digestion of TMV-RNA led to a well defined pattern of RNA fragments while 5 S ribosomal RNA and globin mRNA were not degraded. These results provide further evidence that proteasomes are able to discriminate between different RNAs, and the possible involvement of proteasomes in translation control is discussed.
...
PMID:Identification and initial characterization of a specific proteasome (prosome) associated RNase activity. 754 75

We have identified and purified an endogenous inhibitor of multicatalytic proteinase (MCP) from human erythrocyte membranes. The inhibitor showed a molecular mass of 90 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The inhibitor protein was purified from the erythrocyte membranes using Heparinagarose and hydroxylapatite chromatography and the size exclusion on a Biogel A 1.5 m column in the presence of high salt. The 90-kDa protein inhibited all three peptidase activities of MCP; trypsin-like, chymotrypsin-like and peptidyl glutamyl peptide hydrolyzing (PGPH). However, it failed to cause any significant inhibition of caseinolytic activity of MCP, suggesting that the regulation of proteinase and peptidase activities is distinct. The inhibition of the chymotrypsin-like activity was noncompetitive. The results suggest that the 90-kDa inhibitor protein may be an important regulator of membrane-bound MCP.
...
PMID:Identification and purification of a 90-kDa membrane-bound endogenous inhibitor of multicatalytic proteinase from human erythrocytes. 757 69

The peptidase activity of the 20S proteasome (multicatalytic protease complex) was examined in the 100,000g supernatant fraction prepared from rat liver tissue. Fluorogenic substrates for three proteasome peptidase activities were selected on the basis of (i) observation of an accelerated degradation in the presence of sodium dodecyl sulfate (SDS) and (ii) preferential degradation by the proteasome. Peptidase activities were assayed using an immunoprecipitation technique utilizing polyclonal antibodies raised against the purified rat proteasome. The ability to demonstrate SDS activation of the proteasome is shown to be dependent upon the choice of substrate. In addition, among the cytosolic peptidases, the property of SDS activation appears to be unique to the proteasome. SDS activation profiles were determined for each peptidase activity. Chymotrypsin-like and peptidylglutamyl peptide-hydrolyzing activities exhibit a broad plateau of activation between 0.04 and 0.05% SDS. Trypsin-like activity exhibits a sharp peak of activation at an SDS concentration of 0.04%. The SDS activation profile can be altered by changing the protein (proteasome) concentration, i.e., increasing protein (proteasome) concentration of the reaction mixture produces a marked rightward shift of the activation profile. On the other hand, changing the substrate concentration does not alter the profile. In conclusion, a technique for measuring proteasome peptidase activity in the 100,000g supernatant has been described. This approach increases the ease of measurement of peptidase activity and provides data which may more closely reflect the in vivo activity of the proteasome.
...
PMID:Sodium dodecyl sulfate (SDS) activation of the 20S proteasome in rat liver. 763 16


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

---