Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have shown that depletion of monocytes from human peripheral blood mononuclear cells (PBMC) by L-phenylalanine methyl ester (PheOMe) enhanced lymphokine-activated killer cell (LAK) generation by recombinant interleukin-2 (rIL-2) at high cell density. In this study, we have investigated the mechanism of action of PheOMe on LAK activation by using trypsin, chymotrypsin, tosylphenylalaninechloromethanol (TPCK, a chymotrypsin inhibitor), tosyl-L-lysinechloromethane (TLCK, a trypsin inhibitor), phenylalaninol (PheOH), and benzamidine. PBMC were treated with 1-5 mM PheOMe for 40 min at room temperature in combination with the various agents, washed and assessed for their effects on natural killer (NK) activity against K562 cells and monocyte depletion. The treated cells were then cultured with or without rIL-2 for 3 days. LAK cytotoxicity was assayed against 51Cr-labeled K562 and Raji tumor target cells. TPCK at 10 micrograms/ml partially inhibited depletion of monocytes by PheOMe. TLCK did not prevent depletion of monocytes nor inhibition of NK activity induced by PheOMe. TPCK and TLCK inhibited NK activity by themselves. TPCK but not TLCK inhibited rIL-2 induction of LAK cells. On the other hand, PheOH and benzamidine (analogs of PheOMe) lacked any effect on monocyte depletion but abrogated the inhibitory effect of PheOMe on NK activity. They had no effect on rIL-2 activation of LAK activity enhanced by PheOMe. Trypsin potentiated the inhibitory effect of PheOMe on NK activity and monocyte depletion. Trypsin partially inhibited IL-2 activation of LAK activity enhanced by PheOMe. Chymotrypsin had little effect on NK activity but prevented the inhibitory effect of PheOMe on NK activity. It had little effect on monocyte depletion induced by PheOMe. PheOMe was hydrolysed by monocytes and chymotrypsin to Phe and methanol as determined by HPLC. TPCK inhibited hydrolysis of PheOMe by monocytes. Our data suggest that the effects of PheOMe on monocytes, NK cells and LAK activation involve protease activities of monocytes.
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PMID:Human lymphokine-activated killer (LAK) cells: III. Effect of L-phenylalanine methyl ester on LAK cell activation from human peripheral blood mononuclear cells: possible protease involvement of monocytes, natural killer cells and LAK cells. 176 Aug 8

The requirement for serine esterase activity in antibody-dependent cellular cytotoxicity (ADCC) in human neutrophils against Raji target cells has been investigated. The lysis was prevented when the serine esterase inhibitors TPCK and TLCK (chloromethyl-ketone derivatives of tosylamino acids) were introduced into the system. Moreover, neutrophils pretreated with TPCK or TLCK and washed were inhibited as well, via a process unaffected by the presence of adequate amounts of enzymatic substrates. This suggests that the inhibition mediated by TPCK and TLCK is independent of serine esterase blockade, therefore implying the inactivation of some other step crucial to the lysis. The addition of synthetic chymotrypsin substrates (tyrosine and phenylalanine esters) impaired the Raji cell lysis in a dose-related manner without altering the constitution of neutrophil-target conjugates. Trypsin ester substrates were ineffective. These results are in agreement with the involvement of a serine esterase activity with chymotrypsin-like specificity, which should participate in the lysis at a post-binding step. We conclude that neutrophil-mediated ADCC, as developed in our model system, needs the intervention of a serine esterase or esterases, like other systems of cell-mediated cytotoxicity.
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PMID:Antibody-dependent tumour cytolysis by human neutrophils: effect of synthetic serine esterase inhibitors and substrates. 366 87

Conditioned medium from a human myelomonocytic cell line THP-1 promoted the growth of a wide variety of cell types, i.e., human and mouse myeloid cells (HL-60, U937, K562, and M1), mouse T-cells (EL-4), human B cells (Daudi and Raji), mouse mastocytoma cells (IC-2), human melanoma cells (A375-C6), mouse transformed fibroblast cells (L929), human lung fibroblast cells (TIG-1), and mouse bone marrow fibroblast/stromal-like cells. The growth-promoting activity was acid-labile. The activity was resistant to 50 degrees C for 5 min but completely lost in 5 min at 70 degrees C. The activity was resistant to treatment with trypsin but sensitive to chymotrypsin alpha, Pronase E, and proteinase K, indicating the proteinous nature of this activity. The activity was lost by dithiothreitol and 2-mercaptoethanol. Molecular weight (M(r) 50,000-70,000) was estimated by gel filtration-high performance liquid chromatography. After the sequential anion exchange, hydrophobic, and hydroxylapatite high performance liquid chromatography, the partially purified factor exhibited the same target cell spectrum as the conditioned medium.
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PMID:Human myelomonocytic cell line THP-1 produces a novel growth-promoting factor with a wide target cell spectrum. 846 8

The GC-rich segment containing GGAGGC (Alu core) is conserved within the RNA polymerase III (pol III) promoters of Alu family sequences. We have shown that the GGAGGC motif functions as a modulator of DNA replication as well as of transcription, and identified the proteins binding to the motif in human HeLa cells. In this study, the Alu core binding proteins were partially purified from human Raji cells by using an Alu core DNA affinity column. Both the proteins thus purified were implied to be subunits of Ku antigen based on the following criteria: The molecular weights of the proteins estimated on gel electrophoreses were 70 and 85 kDa, respectively, under denaturing conditions, while under non-denaturing conditions only one band was observed for the same sample at 150 kDa, probably representing hetero-dimer formed between the 70 and 85 kDa proteins. The sizes and the hetero-dimer formation are reminiscent of the 70 and 80 kDa subunits of Ku antigen (Ku-p70 and Ku-p80). Moreover, the purified proteins were immunoreactive with anti-Ku antibodies, and the specific DNA-protein complex on the Alu core element was cancelled by the anti-Ku antibodies. The nucleoprotein complex showed the same clipping patterns as those of the complex between the Alu core element and an authentically purified Ku antigen after proteolytic cleavage with trypsin and chymotrypsin.
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PMID:Ku antigen binds to Alu family DNA. 950 18