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151.
Wysocka M Legowska A Bulak E Jaśkiewicz A Miecznikowska H Lesner A Rolka K 《Molecular diversity》2007,11(2):93-99
Specificity of human cathepsin G was explored using combinatorial chemistry methods. Deconvolution of a tetrapeptide library,
where 5-amino-2-nitrobenzoic acid served as a chromophore attached at the C-terminus, yielded the active sequence Phe-Val-Thr-Tyr-Anb5,2-NH2. This sequence was used for a second-generation library with the general formula Ac-Phe-Val-Thr-X-Anb5,2-NH2, where position X was replaced with several amino acids: l-pyridyl- alanine (Pal), 4-nitro-l-phenylalanine (Nif), 4-amino-l- phenylalanine (Amf), 4-carboxy-l-phenylalanine (Cbf), 4-guanidine-l-phenylalanine (Gnf), 4-methyloxycarbonyl- l-phenylalanine (Mcf), 4-cyano-l-phenylalanine (Cyf), Phe, Tyr, Arg and Lys. Specificity ligand parameters, k
cat and K
M, with human cathepsin G were determined for all chromogenic substrates synthesized. The highest value of the specificity
constant (k
cat/K
M) was obtained for a substrate with the Gnf residue in position P1. This peptide was 10 times more active than the second most active substrate which contained the Amf residue. The following
order of potency was established: Gnf > > Amf > Tyr = Phe > Arg= Lys > Cyf. Substrate specificity for cathepsin G is greatly
enhanced when an aromatic side chain and a strong positive charge are incorporated in residue P1. 相似文献
152.
A rapid, homogenous, antibody-free assay for phosphatase enzymes was developed using the phosphorescent platinum (II)-coproporphyrin label (PtCP) and time-resolved fluorescent detection. An internally quenched decameric peptide substrate containing a phospho-tyrosine residue, labeled with PtCP-maleimide and dabcyl-NHS at its termini was designed. Phosphatase catalysed dephosphorylation of the substrate resulted in a minor increase in PtCP signal, while subsequent cleavage by chymotrypsin at the dephosphorylated Tyr-Leu site provided a 3.5 fold enhancement of PtCP phosphorescence. This phosphorescence phosphatase enhancement assay was optimized to a 96 well plate format with detection on a commercial TR-F plate reader, and applied to measure the activity and inhibition of alkaline phosphatase, recombinant human CD45, and tyrosine phosphatases in Jurkat cell lysates within 40 min. Parameters of these enzymatic reactions such as Km's, limits of detection (L.O.D's) and IC50 values for the non-specific inhibitor sodium orthovanadate were also determined. 相似文献
153.
Non-invasive measurements of cellular function in in vitro cultured cell lines using vibrational spectroscopy require the
use of spectroscopic substrates such as quartz, ZnSe and MirrIR etc. These substrates are generally dissimilar to the original
in vivo extracellular environment of a given cell line and are often tolerated poorly by cultured cell lines resulting in
morphological and functional changes in the cell. The present study demonstrates various correlations between vibrational
spectroscopic analyses and biochemical analyses in the evaluation of the interaction of a normal human epithelial keratinocyte
cell line (HaCaT) with MirrIR and quartz substrates coated with fibronectin, laminin and gelatin. The findings of this study
suggest that there is a correlation between quantitative measurements of cellular proliferative capacity and viability and
peak area ratios in FTIR spectra, with replicated differences in similar areas of the observed Raman spectra. Differences
in the physiology of cells were observed between the two spectroscopic substrates coated in fibronectin and laminin, but little
differences were observed when the cells were attached to gelatin-coated quartz and MirrIR slides. The correlations demonstrate
the sensitivity of the spectroscopic techniques to evaluate the physiology of the system. Furthermore the study suggests that
gelatin is a suitable coating for use in spectroscopic measurements of cellular function in human keratinocytes, as it provides
a material that normalises the effect of substrate attachment on cellular physiology. This effect is likely to be cell-line
dependent, and it is recommended that similar evaluations of this effect are performed for those combinations of spectroscopic
substrate and cell lines that are to be used in individual experiments. 相似文献
154.
155.
A new crystal growth theoretical model is established for the low-dimensional nanocrystals on an isotropic and quasifree sustained substrate. The driven mechanism of the model is based on the competitive growth among the preferential growth directions of the crystals possessing anisotropic crystal structures, such as the hexagonal close-packed and wurtzite structures. The calculation results are in good agreement with the experimental findings in the growth process of the lowdimensional Zn nanocrystals on silicone oil surfaces. Our model shows a growth mechanism of various low-dimensional crystals on/in the isotropic substrates. 相似文献
156.
染料敏化太阳电池研究进展 总被引:7,自引:0,他引:7
本文介绍了染料敏化太阳电池(DSC)的结构和基本原理,综述了DSC各项关键技术的实验和产业化研究最新成果。对DSC中的几个重要组成部分:纳米半导体薄膜、染料敏化剂、氧化还原电解质、对电极和导电基底材料等几个方面的研究进展进行了详细的评述。回顾了DSC从实验室小电池研究到大规模产业化研究的发展,对该领域未来发展前景进行了展望。 相似文献
157.
158.
透明基底表面双向反射分布函数及粗糙度特性研究 总被引:1,自引:1,他引:0
采用双向反射分布函数定量分析透明基底表面粗糙度,考虑到透明基底第二个界面的影响,从不透明基底双向反射分布函数入手,推导了实际测量的透明基底表面双向反射分布函数的表达式.依据此理论提出了通过分别测量两个表面的散射强度来联立求解透明基底实际表面反射分布函数和表面粗糙度谱的新方法.并将此结果与用原子力显微镜测量所获得的结果进行了比较,两者吻合较好. 相似文献
159.
Rodrigo Lira de Oliveira Suzana Pedroza da Silva Attilio Converti Tatiana Souza Porto 《Molecules (Basel, Switzerland)》2022,27(19)
Inulinases are enzymes involved in the hydrolysis of inulin, which can be used in the food industry to produce high-fructose syrups and fructo-oligosaccharides. For this purpose, different Aspergillus strains and substrates were tested for inulinase production by solid-state fermentation, among which Aspergillus terreus URM4658 grown on wheat bran showed the highest activity (15.08 U mL−1). The inulinase produced by this strain exhibited optimum activity at 60 °C and pH 4.0. A detailed kinetic/thermodynamic study was performed on the inulin hydrolysis reaction and enzyme thermal inactivation. Inulinase was shown to have a high affinity for substrate evidenced by very-low Michaelis constant values (0.78–2.02 mM), which together with a low activation energy (19.59 kJ mol−1), indicates good enzyme catalytic potential. Moreover, its long half-life (t1/2 = 519.86 min) and very high D-value (1726.94 min) at 60 °C suggested great thermostability, which was confirmed by the thermodynamic parameters of its thermal denaturation, namely the activation energy of thermal denaturation (E*d = 182.18 kJ mol−1) and Gibbs free energy (106.18 ≤ ΔG*d ≤ 111.56 kJ mol−1). These results indicate that A. terreus URM4658 inulinase is a promising and efficient biocatalyst, which could be fruitfully exploited in long-term industrial applications. 相似文献
160.
Vivien Herrscher Clea Witjaksono Dr. Marie Buchotte Dr. Claire Ferret Dr. Fabien Massicot Dr. Jean-Luc Vasse Dr. Franck Borel Prof. Dr. Jean-Bernard Behr Dr. Myriam Seemann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(30):e202200241
IspG (also called GcpE) is an oxygen-sensitive [4Fe-4S] enzyme catalyzing the penultimate step of the methylerythritol phosphate (MEP) pathway, a validated target for drug development. It converts 2-C-methyl-d -erythritol-2,4-cyclo-diphosphate (MEcPP) into (E)-4-hydroxy-3-methyl-but-2-enyl-1-diphosphate (HMBPP). The reaction, assimilated to a reductive dehydration, involves redox partners responsible for the formal transfer of two electrons to substrate MEcPP. The 2-vinyl analogue of MEcPP was designed to generate conjugated species during enzyme catalysis, with the aim of providing new reactive centers to be covalently trapped by neighboring amino acid residues. The synthesized substrate analogue displayed irreversible inhibition towards IspG. Furthermore, we have shown that electron transfer occurs prior to inhibition; this might designate conjugated intermediates as probable affinity tags through covalent interaction at the catalytic site. This is the first report of an irreversible inhibitor of the IspG metalloenzyme. 相似文献