Development of monoclonal antibodies against creatine kinase MB2

Screening for transient biological interactions as applied to albumin ligands: A new concept for drug discovery

The notion that many biological interactions are based on transient binding (dissociation constants (K(d)) in the range of 10-0.01 mM) is familiar, yet the implications for biological sciences have been realized only recently. An important area of biological sciences is drug design, where the traditional "lock and key" view of binding has prevailed and drug candidates are usually selected on their merits as being tight binders. However, the rationale that transient interactions are of importance for drug discovery is slowly gaining acceptance. These interactions may relate not only to the desired target interaction but also to unwanted interactions creating, for example, toxicity problems. Here we demonstrate, in a high-throughput screening format, affinity selection of weak binders to a model target of albumin by zonal retardation chromatography. It is perceived that this approach can define the "transient drug" as a complement to current drug discovery procedures.

Analysis of the specificity and thermodynamics of the interaction between low affinity antibodies and carbohydrate antigens using fluorescence spectroscopy

The purpose of this work has been to examine whether fluorescence spectroscopy can be used to investigate weak or transient binding between monoclonal antibodies and carbohydrate antigens. In earlier studies we have demonstrated that the three monoclonal antibodies 39.4 (IgG2b), 39.5 (IgG2b) and 61.1(IgG3) bind weakly to the glycosidic alpha(1-4) bond present in e.g. maltose and panose. In this study these antibodies showed an enhancement in the fluorescence intensity of tryptophan upon binding in solution to these two carbohydrate antigens. Using a structural analog to maltose, cellobiose, no fluorescence intensity change was induced. Dissociation constants for these antibodies at different temperatures (5-40 degrees C) were obtained in the range of 0.003-0.2 mM and they were in accordance with earlier data from studies on affinity chromatography and surface plasmon resonance. Almost a doubling of the dissociation constants was observed for every 10 degrees C increase in temperature, giving an exothermal reaction with standard enthalpy change of -51 kJ/mol, for the association between antibody and carbohydrate antigen. It was seen that the extra glycosyl ring in panose increased the affinity more than eight times for the monoclonal antibody 39.5. A standard entropy increase of 21%, probably due to hydrophobic effects, is introduced by the extra glycosyl ring, while the enthalpy stays unaffected. This direct fluorescence approach to measure the binding and thermodynamics of an interacting antigen-antibody pair is simple and accurate since measurements are performed in solution and no immobilization or fluorophore labeling of the components is required. Introduction of fluorescence techniques will be a useful complement to current procedures to measure interaction of antibody with antigen and in particular they will offer solutions to detect transiently binding antigens.

A survey of the year 2002 commercial optical biosensor literature

We have compiled 819 articles published in the year 2002 that involved commercial optical biosensor technology. The literature demonstrates that the technology's application continues to increase as biosensors are contributing to diverse scientific fields and are used to examine interactions ranging in size from small molecules to whole cells. Also, the variety of available commercial biosensor platforms is increasing and the expertise of users is improving. In this review, we use the literature to focus on the basic types of biosensor experiments, including kinetics, equilibrium analysis, solution competition, active concentration determination and screening. In addition, using examples of particularly well-performed analyses, we illustrate the high information content available in the primary response data and emphasize the impact of including figures in publications to support the results of biosensor analyses.

Improvement of Homogeneity of Analytical Biodevices by Gene Manipulation

Homogeneity is proposed for evaluation of the quality of analytical biodevices, such as biosensors and biochips. As a demonstration, glucose oxidase (GOx) was modified at its C-terminal with a linker peptide with a cysteine residue at the end. The fusion structure (GOx-linker-cysteine) enables the enzyme to immobilize on gold surfaces with a Cys-S-Au bond or to immobilize on a silanized glass surface via disulfide chemistry. With this fusion structure, the enzyme can be anchored onto the substrate with well-controlled orientation, thus forming a homogeneous biological layer on biodevices. The linker peptide between GOx and the cysteine acts as a spacer to reduce the steric hindrance caused by the bulky body of the enzyme. Biochemistry experiments showed that this genetically modified glucose oxidase (shortened to GOxm) retained most of its catalytic characteristics, with K(m) and K(cat) similar to those of the wild-type GOx. Electrochemistry experiments showed that GOxm-modified electrode gave higher and more stable current responses than the electrode modified with GOx which has no free -SH on its surface. The coefficients of variation (used for evaluation of the interchangeability of the enzyme device from the same batch preparation) were 9.5% for the GOxm gold electrode and 20.0% for the GOx gold electrode and the GOxm oxygen electrode. The relative errors (used for evaluation of the precision of the individual enzyme device) were 2.9% for the GOxm gold electrode, 12.0% for the GOx gold electrode, and 11.2% for the GOxm oxygen electrode. Atomic force microscopy images revealed that GOxm formed a self-assembled monolayer in a hexagonal-like lattice packing arrangement on the gold surface, while GOx formed multilayer assembling or aggregated particles. The homogeneity of the protein chips, the GOxm array that was prepared through -S-S- formation, and the GOx array that was prepared through nonspecific adsorption was evaluated. The coefficients of variation, calculated with the signal level of all dots, were 5.4% for the GOxm array and 81.8% for the GOx array. All experimental results pointed to the fact that the homogeneity of the analytical biodevices could be considerably improved by using the proposed method.