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971.
Fangyu Zhou Andrew Kroetsch Vyncent P. Nguyen Xiao Huang Ogechi Ogoke Natesh Parashurama Sheldon Park 《Biotechnology journal》2019,14(5)
Direct chemical labeling of antibody produces molecules with poorly defined modifications. Use of a small antibody‐binding protein as an adapter can simplify antibody functionalization by forming a specific antibody‐bound complex and introducing site‐specific modifications. To stabilize a noncovalent antibody complex that may be used without chemical crosslinking, a bivalent antibody‐binding protein is engineered with an improved affinity of interaction by joining two Z domains with a conformationally flexible linker. The linker is essential for the increase in affinity because it allows simultaneous binding of both domains. The molecule is further circularized using a split intein, creating a novel adapter protein (“lasso”), which binds human immunoglobulin G1 (IgG1) with K D = 0.53 n m and a dissociation rate that is 55‐ to 84‐fold slower than Z. The lasso contains a unique cysteine for conjugation with a reporter and may be engineered to introduce other functional groups, including a biotin tag and protease recognition sequences. When used in enzyme‐linked immunosorbent assay (ELISA), the lasso generates a stronger reporter signal compared to a secondary antibody and lowers the limit of detection by 12‐fold. The small size of the lasso and a long half‐life of dissociation make the peptide a useful tool in antibody detection and immobilization. 相似文献
972.
973.
Carbon dots (CDs), as an attractive zero-dimensional carbon nanomaterial with unique photoluminescent merits, have recently exhibited significant application potential in gas sensing as a result of their excellent optical/electronic characteristics, high chemical/thermal stability, and tunable surface states. CDs exhibit strong light absorption in the ultraviolet range and tunable photoluminescence characteristics in the visible range, which makes CDs an effective tool for optical sensing applications. Optical gas sensor based on CDs have been investigated, which generally responds to the target gas by corresponding changes in optical absorption or fluorescence. Moreover, electrical gas sensor and quartz crystal microbalance sensor whose sensing layer involves CDs have also been designed. Electrical gas sensor exhibits an increase or a decrease in electrical current, capacitance, or conductance once exposed to the target gas. Quartz crystal microbalance sensor responds to the target gas with a frequency shift. CDs greatly promote the absorption of the target gas and improve the sensitivity of both sensors. In this review, we aim to summarize different types of gas sensors involving CDs, and sensing performances of these sensors for monitoring diverse gases or vapors, as well as the mechanisms of CDs in different types of sensors. Moreover, this review provides the prospect of the potential development of CDs based gas sensors. 相似文献
974.
Protein ubiquitination regulates almost all eukaryotic cellular processes, and is of very high complexity due to the diversity of ubiquitin (Ub) modifications including mono-, multiply mono-, homotypic poly-, and even heterotypic poly-ubiquitination. To accurately elucidate the role of each specific Ub signal in different cells with spatiotemporal resolutions, a variety of chemical biology tools have been developed. In this review, we summarize some recently developed chemical biology tools for ubiquitination studies and their applications in molecular and cellular biology. 相似文献
975.
Phosphatidic acid (PA) is the simplest phospholipid and is involved in the regulation of various cellular events. Recently, we developed a new PA sensor, the N-terminal region of α-synuclein (α-Syn-N). However, whether α-Syn-N can sense physiologically produced, endogenous PA remains unclear. We first established an inactive PA sensor (α-Syn-N-KQ) as a negative control by replacing all eleven lysine residues with glutamine residues. Using confocal microscopy, we next verified that α-Syn-N, but not α-Syn-N-KQ, detected PA in macrophagic phagosomes in which PA is known to be enriched, further indicating that α-Syn-N can be used as a reliable PA sensor in cells. Finally, because PA generated during neuronal differentiation is critical for neurite outgrowth, we investigated the subcellular distribution of PA using α-Syn-N. We found that α-Syn-N, but not α-Syn-N-KQ, accumulated at the peripheral regions (close to the plasma membrane) of neuronal growth cones. Experiments using a phospholipase D (PLD) inhibitor strongly suggested that PA in the peripheral regions of the growth cone was primarily produced by PLD. Our findings provide a reliable sensor of endogenous PA and novel insights into the distribution of PA during neuronal differentiation. 相似文献
976.
Summary From equilibrium thermodynamics an equation is given to show that in a liquid negative pressures (tensions) are physical reality and may reliably be recorded from any point of the aqueous phase within the xylem conduit by the xylem pressure probe introduced by Balling et al. (Naturwissenschaften 75: 409–411, 1988). 相似文献
977.
A theoretical model is developed for an electrochemical sensor for toxic substances which works by measuring the inhibition of the enzyme activity. The enzyme is assumed to follow Michaelis-Menten kinetics and the diffusion kinetic equation describing the concentration profile of the enzyme's substrate in the electrolyte layer between the electrode and the membrane covering the electrode is solved. A complete set of analytical solutions is found which corresponds to a number of different rate limiting processes. The set of solutions is described in a case diagram. The use of cytochrome oxidase in particular is discussed. 相似文献