The specific interaction between sense and antisense peptides was studied by high-performance affinity chromatography (HPAC) and quartz crystal microbalance (QCM) biosensor. Fragment 1-14 of human interferon-β (hIFN-β) was chosen as sense peptide and its three antisense peptides (AS-IFN 1, AS-IFN 2, and AS-IFN 3) were designed according to the degeneracy of genetic codes. The affinity column was prepared with sense peptide as ligand and the affinity chromatographic behavior was evaluated. Glu-substituted antisense peptide (AS-IFN 3) showed the strongest binding to immobilized sense peptide at pH 7.5. A quartz crystal microbalance-flow injection analysis (QCM-FIA) system was introduced to investigate the recognition process in real-time. The equilibrium dissociation constants between sense peptide and AS-IFN 1, AS-IFN 2 and AS-IFN 3 measured 2.08×10-4, 1.31×10-4 and 2.22× 10-5 mol/L, respectively. The mechanism study indicated that the specific recognition between sense peptide and AS-IFN 3 was due to sequence-dependent and multi-modal affinity interaction.
LUO Jia HUANG YanYan XIONG ShaoXiang LIU GuoQuan ZHAO Ruit
1-Imino nitroxide pyrene 1 has been characterized as a H^＋ fluorescent switch. The effects of various interfering species, solvents and the irradiation of ultraviolet light on the fluorescence intensity of 1 are also investigated. 1 fluoresces weakly in the 85% ethanol media containing no more than 4.5x10-5 mol/L of H^＋ （HCI）, but can produce a burst increase of about 4 times in the fluorescence intensity when the concentration of H＋ is increased to or over 4.9×10^-5mol/L. The extremely sharp response of 1 to H＋ occurs only within such a narrow concentration range. Moreover, the decrease of H^＋ concentration through adding sodium hydroxide causes the fluorescence quenching, suggesting that 1 may serve as a fluorescent switch for monitoring the concentration change of H＋ around the point of 4.5×10^-5 mol/L.
Jun LIHong Mei WANGHui Min MADe Qing ZHANGShao Xiang XIONG
New matrix, metal-phthalocyanine （MPc）, of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF MS） was used for analysis of small molecules （usually 〈500 Da）. By using MPcs as matrices, small molecular samples were moved to high mass-to-charge region where there was no interference caused by the traditional matrices. The mass of the target analvte was obtained by simple calculation.
Shu ZhangYi ChenJian An LiuShao Xiang XiongGuang Hui WangxJun ChenGuo Qiang Yang
A method of color surface plasmon resonance imaging was developed and true color SPR images of solvents and BSA microdot arrays were recorded by using our laboratory-built device.The color signals,which were observed to be complementary to the resonance absorption of the incident light,depended on the feature of samples and the incident angle as expected.This new method looks to be a potential color analytical tool for high throughput detection of biochips.
A method for the fast and accurate measurement of diffusion coefficient of minute proteins was developed. A protein sample plug was introduced into the capillary and forced to flow through a capillary coated dynamically by poly(diallyldimethylammonium chloride). Its concentration profile was then monitored by the UV absorption detector mounted on Beckman MDQ capillary electrophoresis system. Accurate diffusion coefficient was obtained. The key conditions for the accurate measurement include: (1) systematic peak should be developed in a laminar flow; (2) radius diffusion is negligible compared with the longitudinal diffusion; (3) the capillary is well thermostated and (4) the solute should not be overloaded. In common case, the deviation of the measurement was kept within 4%.
