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)

The 1.8-A resolution structure of the ATP-Mg(2+)-Ca(2+)-pyruvate quinary complex of Escherichia coli phosphoenolpyruvate carboxykinase (PCK) is isomorphous to the published complex ATP-Mg(2+)-Mn(2+)-pyruvate-PCK, except for the Ca(2+) and Mn(2+) binding sites. Ca(2+) was formerly implicated as a possible allosteric regulator of PCK, binding at the active site and at a surface activating site (Glu508 and Glu511). This report found that Ca(2+) bound only at the active site, indicating that there is likely no surface allosteric site. (45)Ca(2+) bound to PCK with a K(d) of 85 micro M and n of 0.92. Glu508Gln Glu511Gln mutant PCK had normal activation by Ca(2+). Separate roles of Mg(2+), which binds the nucleotide, and Ca(2+), which bridges the nucleotide and the anionic substrate, are implied, and the catalytic mechanism of PCK is better explained by studies of the Ca(2+)-bound structure. Partial trypsin digestion abolishes Ca(2+) activation (desensitizes PCK). N-terminal sequencing identified sensitive sites, i.e., Arg2 and Arg396. Arg2Ser, Arg396Ser, and Arg2Ser Arg396Ser (double mutant) PCKs altered the kinetics of desensitization. C-terminal residues 397 to 540 were removed by trypsin when wild-type PCK was completely desensitized. Phe409 and Phe413 interact with residues in the Ca(2+) binding site, probably stabilizing the C terminus. Phe409Ala, DeltaPhe409, Phe413Ala, Delta397-521 (deletion of residues 397 to 521), Arg396(TAA) (stop codon), and Asp269Glu (Ca(2+) site) mutations failed to desensitize PCK and, with the exception of Phe409Ala, appeared to have defects in the synthesis or assembly of PCK, suggesting that the structure of the C-terminal domain is important in these processes.
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PMID:Mechanisms of activation of phosphoenolpyruvate carboxykinase from Escherichia coli by Ca2+ and of desensitization by trypsin. 1283 99

Phosphenolpyruvate (PEP) carboxylase from leaves of Crassula argentea displays varying levels of sensitivity to inactivation by various proteolytic enzymes. In general, the native enzyme is sensitive to proteinases known to attack at the carbonyl end of lysine or arginine (trypsin, papain, or bromelain). The ineffective proteolytic enzymes are those which have low specificity or which attack at the N-terminal end of hydrophobic amino acids, or which cannot attack lysine. The lack of an effect of endoproteinase arginine C, which is specific for arginine, probably indicates that lysine is the critical residue. When the native enzyme, which is comprised of an equilibrium of dimers with tetramers in approximately equal quantities, is treated by preincubation with 5 millimolar PEP, the enzyme becomes much more resistant to proteolytic inactivation. When the preincubation is with 5 millimolar malate rather than buffer alone, the effect is to slightly increase (ca. 15%) the sensitivity of the enzyme to inactivation by trypsin as measured by estimates of the pseudo-first order rate constant for inactivation. PEP carboxylase from corn leaves appears to be relatively susceptible to inactivation by trypsin, but is unaffected by preincubation with malate or PEP. The sensitivity of this C(4) enzyme to inhibition by malate is also unaffected by preincubation with these ligands.
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PMID:Oligomerization and the sensitivity of phosphoenolpyruvate carboxylase to inactivation by proteinases. 1666 31

In order to investigate differences in fat metabolism during embryonic development, a comparative proteomics strategy was employed using Arbor Acres (AA) and San Huang (SH) broiler chickens with different growth and fat deposition characteristics. These birds were floor-reared and fed identical diets, and embryonic livers were collected from AA and SH chicken embryos on days 9, 14 and 19 of incubation and hatching. Proteins were extracted and fractionated by two-dimensional electrophoresis (2-DE), Neuhoff's colloidal Coomassie Blue G-250 staining was carried out, and stained gels were scanned and analyzed using PDQuest7.3 software (Bio-Rad). In-gel trypsin digestion of the differential protein spots and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) were subsequently assessed. Peptide mass fingerprinting of the differentially expressed proteins was performed using the server from MASCOT or either Prospector or ProFound, and 37 proteins were successfully identified. In the present study, embryo and liver weights showed a trend toward enhanced growth during embryonic development. Of the 37 identified differential proteins, phosphoenolpyruvate carboxykinase (PEPCK), apolipoprotein A-I (Apo A-I), fatty acid-binding protein (L-FABP) and 3-hydroxy-3-methylglutaryl-Coenzyme A synthase (HMG-CoA synthase) were up-regulated in SH chickens to a greater extent than they were in AA chickens. These observations suggest that the lipid metabolic proteins and enzymes are inherent characteristics that contribute to the apparent differences in fat deposition between the two strains.
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PMID:Use of comparative proteomics to identify key proteins related to hepatic lipid metabolism in broiler chickens: evidence accounting for differential fat deposition between strains. 2004 84

Benzothiazole (BT) has a strong inhibitory effect on the growth and development of a wide spectrum of fungi and insects, such as Botrytis cinerea and Bradysia odoriphaga, that cause serious losses in agriculture. To investigate the underlying antifungal and insecticidal mechanisms of BT, RNA-seq analysis was performed for B. cinerea after BT treatment for 12, 24, and 48 h and for B. odoriphaga after BT treatment for 6 and 24 h. In B. cinerea, the pectin degradation process was inhibited, suggesting a low utilization of carbohydrate sources. As the treatment time was extended, the cell walls of B. cinerea thickened, and increases in melanin synthesis and ion transport were observed. In B. odoriphaga, signaling pathways including MAPK, insulin, adipocytokine, forkhead box class O, and peroxisome proliferator-activated receptor were activated at 6 h, and phosphoenolpyruvate carboxykinase was the core gene in the signal transduction pathways that responded to BT; digestive system and melanogenesis genes were obviously altered at 24 h. In addition, we identified several insecticidal target genes, such as trypsin, aminopeptidase N, and tyrosinase. Benzothiazole significantly affected nutrient metabolism, especially carbohydrate metabolism, in both species, and the pentose and glucuronate interconversions pathway was shared by both species, although the individual genes were different in each species. Overall, our results suggested that BT was a melanogenesis disrupter for the insect but an activator for the fungus. Our findings are helpful for deeply exploring the genes targeted by BT and for developing new pesticide compounds with unique mechanisms of action.
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PMID:Comparison of Transcriptome Profiles of the Fungus Botrytis cinerea and Insect Pest Bradysia odoriphaga in Response to Benzothiazole. 3265 8


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