BLI/SPR Assay Service

Alpha Lifetech has been deeply engaged in protein assays for many years, built a sound platform for protein function assay, and mastered a variety of technical means to verify protein interaction, which can save scientific research or project research time while delivering stable results.

Alpha Lifetech can also provide customers with protein binding assays, protein dna binding assay, Protein rna Interaction assay, Bli assay, spr affinity to meet the experimental needs of different customers.

Introduction To Affinity Test

Proteins are the most critical executive molecules in any form of life responding to the instructions stored in genetic materials. More frequently, proteins do their jobs by acting as role players that interact with other proteins, which is more evident when the function of a protein is examined in the real context of a cell. Identifying the interactions between proteins is very crucial for the biochemistry investigation of an individual protein.

There are several difficulties in the design of small molecule inhibitors of protein interaction: (1) the contact area of protein interaction is larger; (2) The contact surface of protein interaction is flat, and it is difficult to find suitable binding sites to bind small molecule compounds; (3) Low molecular weight compounds are difficult to block protein interactions with high affinity.

Therefore, the selection of targets and the detection of affinity are essential.

Affinity is a characteristic parameter to evaluate the strength of the interaction between two molecules in the reversible reaction process. Binding strength determines the stability and specificity of the interaction between antibody and antigen, and this parameter is an important index for drug discovery and screening. The strength of antibody affinity depends on the degree of coordination between the antibody Paratope and the antigenic epitope used, including the size of the contact area, the closeness of the anastomosis, and the distribution of charged groups and hydrophobic groups

Precipitation methods for affinity determination include the following: ELISA, SPR, BLI, etc. The above techniques can be used for protein binding assay, protein DNA binding assay, Protein rna Interaction assay, etc.

Introduction To BLI Affinity Assay

Bio-Layer Interferometry uses probe biosensors to detect samples directly without any fluorescence or isotope labeling. Through the instrument emitting white light to the sensor surface and collecting the reflected light, the reflection spectrum of different frequencies is affected by the thickness of the light film layer of the biosensor and forms interference. When the molecular biofilm on the biosensor interacts with the molecules in the solution, the thickness of the biolayer increases. BLI enables real-time monitoring of molecular interactions and provides high-precision affinity measurements. 96-well or 384-well BLI assay facilitates high-throughput analysis, which offers greater potential in drug development applications.

Advantages of BLI

	The Advantages of BLI Assay
1	This technology can easily process unpurified samples, such as unfiltered cell culture supernatants and lysates; Interactions between molecules in the biological environment; and samples of viruses or virus-like particles
2	Similar to SPR, data can be fed back in time
3	The detection time of this technology is fast and the flux is high

Fig.1 BLI technology case shows. (Reference: BLI-Based Functional Assay in Phage Display Benefits the Development of a PD-L1-Targeting Therapeutic Antibody - PubMed (nih.gov)

Introduction To SPR Affinity Assay

Spr (surface plasmon resonance) affinity is based on the optical principle, surface plasmon resonance technology uses the plasmon resonance phenomenon on the surface of nano-scale metal films to detect the interaction between molecules. At present, it has become a new method in the study of protein interaction.

Advantages of SPR

	The Advantages of SPR Assay
1	Real-time detection by analyzing the change of the response signal
2	There is no need to label the sample, and the sample maintains the original activity
3	The detection sensitivity is high, and the sample quantity required is small
4	Can detect multiple different biological samples at the same time

Fig.2 Principle of SPR. Reference source: Characterization of Small Molecule-Protein Interactions Using SPR Method - PubMed (nih.gov)

Application of Affinity test

Protein interaction/affinity detection can be applied to various aspects of drug early research and development, screening and identification, preclinical and clinical research, and downstream production quality control. It is also widely used in basic research in life science, biopharmaceutical development, and other fields.

After the recombinant antibody is produced, its affinity must be determined to ensure it can be successfully applied to downstream applications. When polyclonal antibody serum is replaced by monoclonal antibody, its affinity must be measured to select a suitable backup. Because the specific affinity of some monoclonal antibodies to an antigen varies greatly with environmental conditions (such as temperature, PH, ionic composition and strength, etc.) (even very small changes), when selecting a monoclonal antibody for a certain purpose, the affinity should be determined by a method similar to the actual application conditions. Therefore, it can be used to verify the uniformity of monoclonal antibodies and to study the sensitivity of different immunological detection methods.

Sample requirement

Sample Types	Requirement
Antibodies, proteins, peptides, small molecules of compounds, etc	* Buffer solution: PBS, HEPPS, etc. do not contain organic reagents, Tris, EDTA, or DDT; * Protein sample (including antibody): 200ug, concentration >0.5mg/ml; * Peptide sample: 200ug, concentration >1mg/ml; * Small molecule of compound: 1mg, concentration >1mg/ml, purity >90%, soluble in 100%DMSO or water.