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)

Human (HGL) and rabbit (RGL) gastric lipases were cleaved by trypsin and the resulting peptides were characterized. Exposure of HGL to trypsin led to the production of three identified fragments (H1, H2 and H3) resulting from cleavage sites at Lys-4 and Arg-229. Fragments H2 (Lys-4-Arg-229) and H3 (Glu-230-Lys-379) were derived from fragment H1 (Lys-4-Lys-379). The single disulfide bridge (Cys-236-Cys-244) of the molecule is localized in fragment H3. Out of the three cysteine residues conserved in all known gastric lipases, the free sulfhydryl group (Cys-227) was localized in fragment H2. Immunoblots, carried out with the tryptic fragments of HGL and anti-HGL mAbs, revealed that five inhibitory mAbs immunoreacted selectively with the N-terminal fragment H2, whereas two other non inhibitory mAbs immunoreacted exclusively with the C-terminal fragment H3. Trypsin also cleaved RGL at two sites (Arg-55 and Arg-229) leading to four identifiable fragments (R1, R2, R3 and R4). One cleavage site (Arg-229) was found to be identical in both RGL and HGL. We propose that this latter site is localized between the two domains of native gastric lipases.
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PMID:Tryptic cleavage of gastric lipases: location of the single disulfide bridge. 804 45

Rabbit gastric lipase (RGL) was subjected to proteolysis with trypsin and led to cleavage occurring at three defined sites (Lys-4, Arg-55 and Arg-229). The tryptic hydrolysate contained four fragments: Gly-230-Lys-379 (T1), Gly-56-Arg-229 (T2), Ser-5-Arg-55 (T3), as well as a 45 kDa molecular form consisting of peptides T1 and T2 linked by a disulfide bridge. The tryptic hydrolysate of RGL as well as the 55 N-terminal amino acid deleted forms conserved 30% of the initial enzymatic activity in a tributyrin assay. Two out of the three cysteine residues which are present in all the known gastric lipases were found to be involved in a disulfide bridge. Unlike HGL, RGL appears to have a heterogenous pattern of cysteine residues. The 30% enzymatic activity of RGL persisting after trypsin treatment may be attributable to the 45 kDa molecular form (with the Cys-227-Cys-236 or Cys-227-Cys-244 disulfide bridge). Trypsin-treated HGL, which was completely inactivated, showed that a single location of the disulfide bridge existed between cysteine residues 236 and 244. It can be concluded that the existence of one disulfide bridge is necessary to maintain the lipase activity of the 45 kDa form of RGL.
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PMID:An enzymatically active truncated form (-55 N-terminal residues) of rabbit gastric lipase. Correlation between the enzymatic activity and disulfide bond oxydo-reduction state. 967 39

In bioassays with artificial diets, the 17-hydroxygeranyllinalool diterpenoid glycosides (HGL-DTGs) of Nicotiana attenuata function as antifeedants for the plant's adapted herbivore, tobacco hornworm (Manduca sexta). To determine whether HGL-DTGs have a defensive function in planta, we suppressed HGL-DTG production by silencing the source of the geranylgeranyl diphosphates (GGPPs) required for geranyllinalool biosynthesis, a key intermediate. We used virus-induced gene silencing to suppress transcript levels of GGPP synthase gene (Naggpps) and farnesyl diphosphate (FPP) synthase gene (Nafpps), northern blotting and real-time polymerase chain reaction to quantify transcript accumulations, and radio gas chromatography to analyze prenyltransferase specificity. Silencing Nafpps had no effect on the accumulation of HGL-DTGs but decreased leaf steroid content, demonstrating that DTG-synthesizing enzymes do not use GGPP derived from FPP and confirming FPP's role as a steroid precursor. Unlike plants silenced in the phytoene desaturase gene (Napds), which rapidly bleached, Naggpps-silenced plants had reduced HGL-DTG but not carotenoids or chlorophyll contents, demonstrating that Naggpps supplies substrates for GGPP biosynthesis for HGL-DTGs, but not for phytoene or phytol. Expression of Naggpps in Escherichia coli revealed that the recombinant protein catalyzes the GGPP synthesis from isopentenyl diphosphate and dimethylallyl diphosphate. When fed on silenced plants, hornworm larvae gained up to 3 times more mass than those that fed on empty vector control plants or plants silenced in Nafpps, the trypsin protease inhibitor gene, or the putrescine N-methyltransferase gene. We conclude that HGL-DTGs or other minor undetected diterpenoids derived from GGPP function as direct defenses for N. attenuata and are more potent than nicotine or trypsin protease inhibitors against attack by hornworm larvae.
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PMID:Silencing geranylgeranyl diphosphate synthase in Nicotiana attenuata dramatically impairs resistance to tobacco hornworm. 1796 75

In the Great Basin Desert, Nicotiana obtusifolia (synonymous with Nicotiana trigonophylla) and Nicotiana attenuata co-occur, but the former is frequently less attacked by larvae of the tobacco hornworm than the latter, despite having lower nicotine and trypsin protease inhibitor defenses. Glycosides of the diterpene, 17-hydroxygeranyllinalool (HGL-DTGs) have recently been found to be important defenses of N. attenuata. Total HGL-DTG levels are 5-fold higher in N. obtusifolia than in N. attenuata, and we characterize the three major HGL-DTGs purified from N. obtusifolia leaves as: 3-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-17-hydroxygeranyllinalool-17-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranoside; nicotinoside III and its malonic acid conjugates. Using APCI- and ESI-LC-MS, we also identified mono- and diacetyl-nicotinoside III and quercetin glycosides. To evaluate the defensive value of these HGL-DTGs, we used virus-induced-gene silencing to reduce the transcript levels of geranylgeranyl diphosphate synthase and total HGL-DTG levels in both species. When fed on silenced plants, larvae gained up to about two times more mass than those that fed on empty vector control plants of both species. We conclude that HGL-DTGs function as the most important direct defenses for both N. attenuata and N. obtusifolia.
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PMID:17-Hydroxygeranyllinalool glycosides are major resistance traits of Nicotiana obtusifolia against attack from tobacco hornworm larvae. 2045 33