Conformational changes of proteins at an interface induced by a supported planar phosphatidic acid monolayer

High-speed biomarker identification utilizing porous silicon nanovial arrays and MALDI-TOF mass spectrometry

Speed and accuracy are crucial prerequisites in the application of proteomic methods to clinical medicine. We describe a microfluidic-based nanovial array for rapid proteolytic processing linked to MALDI-TOF MS. This microscale format consumes only minute amounts of sample, and it is compatible with rapid bioanalytical protocols and high-sensitivity readouts. Arrays of vials (300 microm in diameter and 25 microm deep), isotropically etched in silicon wafers were electrochemically porosified. Automated picoliter microdispensing was employed for precise fluid handling in the microarray format. Vials were prefilled with trypsin solution, which was allowed to dry. Porosified and nonporosified nanovials were compared for trypsin digestion and subsequent MS identification of three model proteins: lysozyme, alcohol dehydrogenase, and serum albumin at levels of 100 and 20 fmol. In an effort to assess the rapid digestion platform in a context of putative clinical applications, two prostate cancer biomarkers, prostate-specific antigen (PSA) and human glandular kallikrein 2 (hK2), were digested at levels of 100 fmol (PSA), 20 fmol (PSA) and 8 fmol (hK2). All biomarker digestions were completed in less than 30 s, with successful MS identification in the porous nanovial setting.

Kinetic Study of Desorption of Two Species of Bovine Serum Albumin from Alumina during Alkali Elution Process

Kinetics of desorption of irreversibly adsorbed bovine serum albumin (BSA) from alumina (Al2O3) particles at various surface coverages (theta) was studied in a plug-flow column by feeding 0.05 M NaOH solution. The desorption curve obtained by plotting the logarithm of the amount of residual BSA against elution time was analyzed by using an integrated model that describes two simultaneous first-order processes. At each of theta, except for an initial lag time, the curve of BSA desorption could be reduced to the sum of two independent and simultaneous first-order processes occurring at different rates. The desorption rate constant (k(f)) for a faster-desorbing BSA (BSA(f)) was influenced by theta, especially above 0.7. On the other hand, the rate constant (k(s)) for a slower-desorbing BSA (BSA(s)) was fairly constant irrespective of theta and approximately 25- to 100-fold lower than k(f). The amount of BSA(f) estimated was proportional to theta, whereas that of BSA(s) reached a plateau value corresponding to 12.8% of saturation amount at theta above 0.42.

Protein adsorption on solid surfaces

The research field of protein adsorption on surfaces appears to be as popular as ever. In the past year, several hundred published papers tackled problems ranging from fundamental aspects of protein surface interactions to applied problems of surface blood compatibility and protein surface immobilization. Although some parts of the protein adsorption process, such as kinetics and equilibrium interactions, can be accurately predicted, other aspects, such as the extent and the rate of protein conformational change, are still somewhat uncertain. The whole field is ripe for a comprehensive theory on protein adsorption.