Homogeneous preparation of fluorescent-derivatized insulin and its application to competitive chromatographic immunoassays

Determination of hemocoagulase agkistrodon in a pharmaceutical preparation by high-performance liquid chromatography with pre-column derivatization and fluorescence detection

Currently, there is no analytical method for the quantification of hemocoagulase agkistrodon (HCA) in pharmaceutical preparations. This study presents a pre-column derivatization method for the quantification of HCA, a compound extracted from the venom of Agkistrodon acutus, in a pharmaceutical preparation (trade name Suling). In the proposed method, 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate was used to tag the HCA substrate, and the derivatives were analyzed by high-performance liquid chromatography with fluorescence detection. Complete and homogeneous derivatization of HCA was confirmed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry analysis. The specificity of the method was validated by forced degradation, and interference was assessed using a placebo. Under the optimum chromatographic conditions, the calibration curve was linear over a range of 10 to 500 ng/mL, featuring a correlation coefficient of 0.9999. The limits of detection and quantification of the method were 0.57 and 1.6 ng/mL, respectively. The percentage recovery of HCA in quality control samples ranged from 97.49 to 99.15%. Overall, this novel method can be applied to the quantitative determination of HCA in pharmaceutical preparations.

Advances in the study of luminescence probes for proteins

Spectral probes (or labels) have been widely used for the investigation and determination of proteins and have made considerable progress. Traditional luminescence probes include fluorescent derivatizing reagents, fluorescent probes and chemiluminescence probes which continue to develop. Of them, near infrared (NIR) fluorescent probes are especially suitable for the determination of biomolecules including proteins, so their development has been rapid. Novel luminescence probes (such as nanoparticle probes and molecular beacons) and resonance light scattering probes recently appeared in the literature. Preliminary results indicate that they possess great potential for ultrasensitive protein detection. This review summarizes recent developments of the above-mentioned probes for proteins and 195 references are cited.

Site-specific fluorescent derivatization and liquid chromatographic-mass spectrometric characterization of long R(3) IGF-I for bioanalytical applications

Recombinant Long R(3) IGF-I was derivatized with fluorescein isothiocyanate (FITC) at a single location by careful selection of reaction conditions (i.e. pH, and FITC/protein amino group ratio). High-performance liquid chromatography (LC) and electrospray mass spectrometry (MS) were used to confirm the extent of fluorescein conjugation. The protein conjugate was isolated and subjected to cyanogen bromide (CNBr) cleavage, followed by LC-MS to determine the site of modification. The isolated species of Long R(3) IGF-I-FITC was labeled at the N-terminal Met residue. Recognition of this fluorescent analog by monoclonal anti-IGF-I was preserved, indicating its potential for immunodiagnostic applications.