Peptide inhibitors of converting enzyme.

Human plasma and atypical lung converting enzyme, and porcine plasma converting enzyme are substantially inhibited by other components of the renin-angiotensin system, and by angiotensin II and its analogues. Des-Asp¹ angiotensin II (angiotensin III) 0.1 mM and tridecapeptide renin substrate 0.1 mM are both effective inhibitors of human lung, plasma and porcine plasma converting enzymes. Des-Asp¹-Arg² angiotensin II also was an effective inhibitor of plasma enzymes. Bradykininase activity (kininase II) of the converting enzymes was also inhibited by angiotensin I, angiotensin III, tetradecapeptide renin substrate and tridecapeptide renin substrate. The substantial kininase and converting enzyme inhibitory effects of components of the renin-angiotensin system, suggest a potential close physiologic relationship between the kallikrein-kinin system and the renin-angiotensin system.     

New potent inhibitors of angiotensin converting enzyme

Using an earlier model of the favoured orientation of binding functions of angiotensin converting enzyme (ACE) inhibitors, it has been possible to postulate a new, 7,6-bicyclic system, based on hexahydropyridazine, which might be expected to have high potency. Some members of this system which have been synthesised have been shown to be very active ACE inhibitors, in vitro and in vivo.     

Antiviral compounds from traditional Chinese medicines Galla Chinese as inhibitors of HCV NS3 protease

Under the guidance of bioassay, the EtOAc extract fraction of the Traditional Chinese Medicine (TCM) Galla Chinese was found to be efficient in inhibiting the NS3 protease of HCV and purified the fraction to get three polyphenol compounds 1,2,6-tri-O-galloyl-β-D-glucose (1), 1,2,3,6-tetra-O-galloyl-β-D-glucose (2), and 1,2,3,4,6-penta-O-galloyl-β-D-glucose (3), which were identified as inhibitors of Hepatitis C Virus (HCV) NS3 protease. Compounds 1, 2, and 3 inhibited HCV NS3 protease with IC₅₀ of 1.89, 0.75, and 1.60 μM, respectively.     

The history of inhibitors of angiotensin converting enzyme.

This review paper by Sir John Vane, The Nobel Prize Laureate for the first time reveals the insides of discovery of inhibitors of angiotensin converting enzyme (ACE-1), presently known as important drugs for the treatment of hypertension, congestive heart failure and coronary artery disease.     

Design of peptide derived amino alcohols as transition-state analog inhibitors of angiotensin converting enzyme

A new amino alcohol modification designed to mimic the putative transition-state of amide bond cleavage by proteolytic enzymes has been incorporated into the scissile bond position of N-benzoyl-Phe-Ala-Pro, a known substrate of angiotensin converting enzyme (ACE). The resulting modified tripeptides (i.e. 4) are shown to be a new class of potent inhibitors of converting enzyme.     

Perindopril and ramipril phosphonate analogues as a new class of angiotensin converting enzyme inhibitors

A series of phosphonate analogues related to perindopril and ramipril were prepared and tested to estimate their ability to inhibit angiotensin converting enzyme. These new synthesized compounds were active ACE inhibitors with a promising activity.     

Kinetics of slow, tight-binding inhibitors of angiotensin converting enzyme

Five phosphorus-containing inhibitors of angiotensin converting enzyme were found to exhibit slow, tight-binding kinetics by using furanacryloyl-L-phenylalanylglycylglycine as substrate at pH 7.50 and T = 25 degrees C. Two of the inhibitors, (O-ethylphospho)-Ala-Pro (2) and (O-isopropylphospho)-Ala-Pro (3), are found to follow at minimum a two-step mechanism of binding (mechanism B) to the enzyme. This mechanism consists of an initial fast formation of a weaker enzyme-inhibitor complex (Ki = 130 nM for 2 and 180 nM for 3) followed by a slow reversible isomerization to a tighter complex with measurable forward (K3) and reverse (k4) rate constants (k3 = 4.5 X 10(-2) s-1 for 2 and 5.4 X 10(-2) s-1 for 3; k4 = 9.2 X 10(-3) s-1 for 2 and 3.5 X 10(-3) s-1 for 3). For the remaining three inhibitors, phospho-Ala-Pro (1), (O-benzyl-phospho)-Ala-Pro (4), and (P-phenethylphosphono)-Ala-Pro (5), a one-step binding mechanism (mechanism A) is observed under the conditions of the experiment. The second-order rate constants k1 (M-1 s-1) for the binding of these inhibitors to converting enzyme are found to have values more than 3 orders of magnitude lower than the diffusion-controlled limit for a bimolecular reaction involving the enzyme, viz., 3.9 X 10(5) for 1, 2.2 X 10(5) for 4, and 4.8 X 10(5) for 5.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synthesis and evaluation of thiazepines as interleukin-1beta converting enzyme (ICE) inhibitors

A series of monocyclic thiazepine inhibitors of interleukin-1beta converting enzyme (ICE) were synthesized in eight steps from commercially available intermediates. In vitro biological evaluation showed the thiazepines to be moderately potent ICE inhibitors, with the most active compound exhibiting an IC50 value of 30 nM in an enzyme inhibition assay. Compounds of this class possessed good selectivity against the related enzymes caspase-3 and caspase-8.     

Non-hydroxamate 5-phenylpyrimidine-2,4,6-trione derivatives as selective inhibitors of tumor necrosis factor-alpha converting enzyme

New inhibitors of tumor necrosis factor-alpha converting enzyme (TACE) were discovered with a pyrimidine-2,4,6-trione in place of the commonly used hydroxamic acid. These non-hydroxamate TACE inhibitors were developed by incorporating a 4-(2-methyl-4-quinolinylmethoxy)phenyl group, an optimized TACE selective P1' group. Several leads were identified with IC50 values around 100 nM in a porcine TACE assay and selective over MMP-1, -2, -9, -13, and aggrecanase.     

Ketomethylureas. A new class of angiotensin converting enzyme inhibitors

The design rationale for a new series of tripeptide derived angiotensin converting enzyme (ACE) inhibitors, which we term "ketomethylureas", is described. Analogs of tripeptide substrates (i.e. N-benzoyl-Phe-Ala-Pro) in which the nitrogen atom of the scissile amide bond and the adjacent asymmetric carbon atom of the penultimate amino acid residue are formally transposed give rise to this novel class of inhibitors. The most potent ketomethylureas inhibit ACE with I50 values in the nM range.     

Large-scale analysis of small RNAs derived from traditional Chinese herbs in human tissues

Plant-derived microRNAs have recently been reported to function in human blood and tissues. Controversy was immediately raised due to possible contamination and the lack of large sample sizes. Here, we report thousands of unique small RNAs derived from traditional Chinese medicine(TCM) herbs found in human blood cells and mouse lung tissues using a large-scale analysis.We extracted small RNAs from decoctions of 10 TCM plants(Ban Zhi Lian, Chai Hu, Chuan Xin Lian, Di Ding Zi Jin, Huang Qin, Jin Yin Hua, Lian Qiao, Pu Gong Ying, Xia Ku Cao, and Yu Xing Cao) and obtained millions of RNA sequences from each herb. We also obtained RNA-Seq data from the blood cells of humans who consumed herbal decoctions and from the lung tissues of mice administered RNAs from herbal decoctions via oral gavage. We identified thousands of unique small RNA sequences in human blood cells and mouse lung tissues. Some of these identified small RNAs from Chuan Xin Lian and Hong Jing Tian could be mapped to the genomes of the herbs, confirming their TCM plant origin. Small RNAs derived from herbs regulate mammalian gene expression in a sequence-specific manner, and thus are a superior novel class of herbal drug components that hold great potential as oral gene-targeted therapeutics, highlighting the important role of herbgenomics in their development.     

酶法辅助强化中药提取过程研究进展

利用酶法强化中药提取已成为中药开发的重要手段,酶法提取因其反应特异性强、高效、条件温和、易于控制等优点而具有广阔的应用前景。介绍了应用于中药材提取过程中的酶法辅助技术,归纳了酶法在中药材重要活性成分提取、中药提取液的澄清纯化中的应用,分析了酶法辅助提取对中药活性组成的影响,提出了酶法与超声技术的结合应用方法。     

Synthesis and evaluation of unsaturated caprolactams as interleukin-1beta converting enzyme (ICE) inhibitors

Peptidomimetic compounds possessing a caprolactam ring constraint were prepared and evaluated as interleukin-1beta converting enzyme (ICE) inhibitors. The caprolactam ring was used to constrain the P3 region of our inhibitors. This strategy proved to be effective for the synthesis of ICE inhibitors, maintaining key hydrogen bond interactions with the enzyme and invoking a preferred conformation for binding. Several compounds exhibited IC(50) values less than 10nM in a caspase-1 enzyme assay and less than 100nM in a THP-1 whole cell assay measuring IL-1beta production. Two compounds, 13c and 13j, were found to have good oral bioavailability (>50%) in rats when administered as prodrugs.     

Purification and characterization of a fibrinolytic enzyme of Bacillus subtilis DC33, isolated from Chinese traditional Douchi

Bacillus subtilis DC33 producing a novel fibrinolytic enzyme was isolated from Ba-bao Douchi, a traditional soybean-fermented food in China. The strong fibrin-specific enzyme subtilisin FS33 was purified to electrophoretic homogeneity using the combination of various chromatographic steps. The optimum temperature, pH value, and pI of subtilisin FS33 were 55°C, 8.0, and 8.7, respectively. The molecular weight was 30 kDa measured by SDS–PAGE under both reducing and non-reducing conditions. The enzyme showed a level of fibrinolytic activity that was about six times higher than that of subtilisin Carlsberg. The first 15 amino acid residues of N-terminal sequence of the enzyme were A-Q-S-V-P-Y-G-I-P-Q-I-K-A-P-A, which are different from that of other known fibrinolytic enzymes. The amidolytic activities of subtilisin FS33 were inhibited completely by 5 mM phenylmethanesulfonyl fluoride (PMSF) and 1 mM soybean trypsin inhibitor (SBTI), but 1,4-dithiothreitol (DTT), β-mercaptoethanol, and p-hydroxymercuribenzoate (PHMB) did not affect the enzyme activity; serine and tryptophan are thus essential in the active site of the enzyme. The highest affinity of subtilisin FS33 was towards N-Succ-Ala-Ala-Pro-Phe-pNA. Therefore, the enzyme was considered to be a subtilisin-like serine protease. The fibrinolytic enzyme had a high degrading activity for the Bβ-chains and Aα-chain of fibrin(ogen), and also acted on thrombotic and fibrinolytic factors of blood, such as plasminogen, urokinase, thrombin, and kallikrein. So subtilisin FS33 was able to degrade fibrin clots in two ways, i.e., (a) by forming active plasmin from plasminogen and (b) by direct fibrinolysis.     

Phenylalkyl ketones as potent reversible inhibitors of interleukin-1β converting enzyme

Phenylalkyl ketones are potent reversible inhibitors of interleukin-1β converting enzyme (ICE). The extended alkyl chain ketones AcTyrValAlaAspCO(CH₂)_nPh display increased potency over the simple aryl ketone. In particular, the tetrapeptide AcTyrValAlaAspCOPh has a K_i of 10μM while AcTyrValAlaAspCO(CH₂)₅Ph has a K_i of 18.5nM.     

Inhibition by angiotensin converting enzyme inhibitors of endothelin secretion from cultured human endothelial cells.

We conducted a study to determine whether angiotensin converting enzyme inhibitors (ACEIs) inhibit endothelin secretion from cultured human endothelial cells. Confluent umbilical vein endothelial cells were incubated in multi-well plates with culture medium containing either captopril (10(-6), 10(-5), 10(-4) M) or enalaprilat (10(-7), 10(-6), 10(-5) M) for 6 hours. Immunoreactive endothelin in the medium was measured by radioimmunoassay. Calf serum (CS) stimulated endothelin release in a concentration-dependent manner, and both ACEIs inhibited 5% CS-stimulated endothelin release in a concentration-dependent manner. To explore the mechanisms of ACEI-induced suppression of endothelin release, the effects of angiotensin II (10(-8), 10(-7), 10(-6) M), angiotensin converting enzyme (0.1, 1, 10 mU/ml), bradykinin (10(-8), 10(-7), 10(-6) M), and sodium nitroprusside (10(-6), 10(-5), 10(-4) M) on endothelin release were also examined. Although angiotensin II and angiotensin converting enzyme had no significant effect on endothelin release, concentration-dependent suppression occurred with bradykinin and sodium nitroprusside. These results indicate that ACEIs inhibit the stimulated release of endothelin from human endothelial cells, and provide indirect evidence that ACEI-induced ET suppression may be mediated via potentiation of autacoid formation from the cells.     

TNF—α转换酶的结构特征及抑制剂

肿瘤环因子－α转换酶（ｔｕｍｏｒ ｎｒｃｒｏｓｉｓ ｆａｃｔｏｒ－α ｃｏｎｖｅ ｒｔｉｎｇ ｅｎｚｙｍｅ,ＴＡＣＥ）将２６ｋＤ膜结合型ＴＮＦ－α前体水解为具有生物活性的可溶性１７ｋＤ ＴＮＦ－α。ＴＡＣＥ基因克隆的成功,主宰其为金属水解蛋白（ａｄａｍａｌｙｓｉｎ）家族的膜结合型异整合素金属蛋白酶。发现许多金属蛋白酶抑制剂ｈｙｄｒｏｘａｍａｔｅ类化全物能抑制ＴＡＣＥ活性阻断ＴＮＦ－α释放,并保护脓毒