Boc-Asp-OBzl

Boc-Asp-OBzl

HIV-1 coat protein gp120 stimulates interleukin-1beta secretion from human neuroblastoma cells: evidence for a role in the mechanism of cell death.[Pubmed:11704656]

Br J Pharmacol. 2001 Nov;134(6):1344-50.

1. The role of the pro-inflammatory cytokine interleukin-1beta (IL-1beta) in the mechanism of cell death induced by the human immunodeficiency virus type 1 (HIV-1) recombinant coat glycoprotein, gp120 IIIB, has been studied in the human CHP100 neuroblastoma cell line maintained in culture. 2. Death of neuroblastoma cells typically elicited by 10 pM gp120 or by human recombinant IL-1beta (10 ng x ml(-1)) has been minimized by the antagonist of IL-1 receptor, i.e. IL-1ra (0.5 and 50 ng x ml(-1), respectively), an endogenous molecule that antagonizes most of the biological actions of IL-1beta, or by an antibody (5 and 50 ng x ml(-1)) which blocks the human IL-1 receptor type I (IL-1RI). 3. ELISA experiments have established that gp120 enhances immunoreactive IL-1beta levels in the culture medium and this is prevented by exposure to the IL-1 converting enzyme (ICE) inhibitor t-butoxycarbonyl-L-aspartic acid benzyl ester-chloromethylketone [Boc-Asp(OBzl)-CMK] used at a concentration (2.5 microM) which significantly (P<0.001) reduces cell death. 4. Death of CHP100 cells induced by gp120 is also prevented by acetyl-Tyr-Val-Ala-Asp-chloromethylketone (Ac-YVAD-CMK; 10-100 microM), a second inhibitor of ICE, supporting the concept that the viral protein stimulates the conversion of the 31 kDa pro-IL-1beta in to the 17 kDa mature cytokine which is then secreted to cause death. 5. In conclusion, our present data demonstrate that gp120 stimulates the secretion of IL-1beta which then triggers CHP100 neuroblastoma cell death via stimulation of IL-1 receptor type I.

Transesterification and amide cis-trans isomerization in Zn and Cd complexes of the chelating amino acid ligand Boc-Asp(Dpa)-OBzl.[Pubmed:17160185]

Dalton Trans. 2007 Jan 7;(1):154-62.

The amino acid derivative Boc-Asp-OBzl (Boc=N-butyloxycarbonyl; Asp=aspartic acid; Bzl=benzyl) was functionalized by coupling its carboxylate side chain to dipicolylamine. This yielded the tridentate nitrogen donor ligand Boc-Asp(Dpa)-OBzl (-OBzl). The compound -OBzl contains three different carbonyl groups: a tertiary amide linkage between Asp and Dpa, a C-terminal benzyl ester function, and an N-terminal urethane protecting group. NMR spectra were used to compare the reactivity of these moieties. The Boc protecting group gives rise to two isomers, (E, 9%) and (Z, 91%). Coordination of Cd(NO3)2 and Zn(NO3)2 yielded the complexes and. These compounds have significantly reduced barriers to rotation about the tertiary amide C-N bond compared with the free ligand (-OBzl:18.5 kcal mol-1 in CDBr3;: 12.9 kcal mol-1 in (CD3)2CO;: 13.8 kcal mol-1 in (CD3)2CO). Both complexes readily undergo transesterification in methanol or CD3OD. Experimental pseudo-first order rate constants were determined in CD3OD and (CD3)2CO:CD3OD (3:1;). It was found that the zinc complex (k=(2.28+/-0.02)x10(-4) s-1) is significantly more reactive than the cadmium complex (k=(1.41+/-0.03)x10(-6) s-1). In order to study their tertiary amide cis-trans isomerization, the cadmium complex [(-OCH3)Cd(NO3)2] was synthesized, and the zinc complex [(-OCD3)Zn(NO3)2] was generated in situ in (CD3)2CO:CD3OD (3:1). The barriers to rotation were determined (:14.1 kcal mol-1 in CD3OD;: 13.4 kcal mol-1 in (CD3)2CO:CD3OD (3:1)). Our results show that the stronger Lewis-acid zinc(II) is significantly more active than cadmium(II) in the acceleration of the transesterification. This is in marked contrast to the tertiary amide bond rotation which is comparably fast with both metal ions.

Purification and characterization of novel trypsin-like serine proteases from mouse spleen.[Pubmed:8743562]

J Biochem. 1996 Apr;119(4):633-8.

Novel trypsin-like serine proteases (mouse trypsin-type serine proteases 1 and 2 [MTSP-1 and -2]) were purified to homogeneity from mouse spleen. Each protease consisted of a single polypeptide with a molecular mass of about 29 kDa, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing conditions. Both were totally inhibited by diisopropylfluorophosphate, soybean trypsin inhibitor, aprotinin, antipain, and leupeptin and partially inhibited by chymostatin and dithiothreitol, suggesting that they are trypsin-like serine proteases. They hydrolyzed synthetic substrates for trypsin-like proteases but not those for chymotrypsin-like proteases, elastase and kallikrein. MTSP-1 hydrolyzed tert-butyloxycarbonyl (Boc)-Asp(OBzl)Pro-Arg-amino-4-methyl-coumaryl-7-amide (MCA) and Boc-Ile-Glu-Gly-Arg-MCA faster than Boc-Phe-Ser-Arg-MCA. On the other hand, MTSP-2 hydrolyzed Boc-Phe-Ser-Arg-MCA most rapidly, with a specific activity 15 times higher than that of MTSP-1. The N-terminal amino acid sequence of MTSP-1 was Ile-Val-Gly-Gly-Tyr-Thr-His-Leu-Asp-Asn-Gln-Val-Pro-Tyr. This sequence was 71% homologous with the N-terminal of bovine trypsin. The Boc-Phe-Ser-Arg-MCA hydrolyzing activity of mouse spleen significantly (p < 0.01) increased to about 1.5-fold the basal activity 2 weeks after an injection of Freund's complete adjuvant, suggesting that these proteases are involved in the immune response.

A novel histochemical method for the visualization of thrombin activity in the nervous system.[Pubmed:26851772]

Neuroscience. 2016 Apr 21;320:93-104.

Although thrombin has an important role in both central and peripheral nerve diseases, characterization of the anatomical distribution of its proteolytic activity has been limited by available methods. This study presents the development, challenges, validation and implementation of a novel histochemical method for visualization of thrombin activity in the nervous system. The method is based on the cleavage of the substrate, Boc-Asp(OBzl)-Pro-Arg-4MbetaNA by thrombin to liberate free 4-methoxy-2-naphthylamine (4MbetaNA). In the presence of 5-nitrosalicylaldehyde, free 4MbetaNA is captured, yielding an insoluble yellow fluorescent precipitate which marks the site of thrombin activity. The sensitivity of the method was determined in vitro using known concentrations of thrombin while the specificity was verified using a highly specific thrombin inhibitor. Using this method we determined the spatial distribution of thrombin activity in mouse brain following transient middle cerebral artery occlusion (tMCAo) and in mouse sciatic nerve following crush injury. Fluorescence microscopy revealed well-defined thrombin activity localized to the right ischemic hemisphere in cortical areas and in the striatum compared to negligible thrombin activity contralaterally. The histochemical localization of thrombin activity following tMCAo was in good correlation with the infarct areas per triphenyltetrazolium chloride staining and to thrombin activity measured biochemically in tissue punches (85 +/- 35 and 20 +/- 3 mU/ml, in the cortical and striatum areas respectively, compared to 7 +/- 2 and 13 +/- 2 mU/ml, in the corresponding contralateral areas; mean +/- SEM; p<0.05). In addition, 24 h following crush injury, focal areas of highly elevated thrombin activity were detected in teased sciatic fibers. This observation was supported by the biochemical assay and western blot technique. The histochemical method developed in this study can serve as an important tool for studying the role of thrombin in physiological and pathological conditions.

Caspase-1 inhibitors abolish deleterious enhancement of COX-2 expression induced by HIV-1 gp120 in human neuroblastoma cells.[Pubmed:12628757]

Toxicol Lett. 2003 Apr 4;139(2-3):213-9.

The human CHP100 neuroblastoma cell line has been shown to provide an useful in vitro model to elucidate the mechanisms underlying HIV-1 gp120 neurotoxicity. Here we report western blotting evidence demonstrating that exposure to a cytotoxic concentration of the viral coat protein up-regulates expression of the inducible isoform of cyclooxygenase (COX-2) in neuroblastoma cells and this seems to be due to the previously observed increase in secreted IL-1beta. In fact, here we show that acetyl-Tyr-Val-Ala-Asp-chloromethylketone (Ac-YVAD-CMK) and t-butoxycarbonyl-L-aspartic acid benzyl ester-chloromethylketone (Boc-Asp-(OBzl)-CMK), two inhibitors of Interleukin-1 Converting Enzyme (ICE; also referred to as caspase-1), abolish COX-2 expression enhanced by gp120 and consequent cell death. In addition, NS-398, a selective inhibitor of COX-2 activity, affords neuroprotection strengthening the role of COX-2 in the mechanisms of death. In conclusion, the present data support the notion that IL-1beta is the signal through which gp120 elevates COX-2 expression and the latter is strongly implicated in the mechanisms underlying cytotoxicity.