Fab, also known as antigen-binding fragment, is a region in the antibody structure that can bind to antigen and consists of a complete light chain (variable and constant regions) and a partial heavy chain structure (variable region and a constant region fragment), with the light chain and the heavy chain connected by a disulfide bond.Fab is small in size, with a molecular weight of 47-48 kDa, and is usually prepared using phage display technology or mammalian cell expression systems.  Fab antibodies have higher tissue permeability and lower immunogenicity than intact IgG antibodies.

    KMD Bioscience combines proven recombinant antibody expression services with phage display technology to prepare antibodies for customers for a wide range of research, diagnostic and therapeutic applications. The expression of recombinant antibodies is an important part of antibody drug development. By continuously optimizing and improving the expression technology, the quality and yield of antibodies can be improved, which will support the clinical application and industrial development of antibody drugs. According to the different types of host cells, protein expression systems can be categorized into prokaryotic and eukaryotic expression systems. Prokaryotic expression system mainly uses E. coli as the host cell, which has the advantages of easy operation and low cost. We can utilize the prokaryotic expression system to produce large quantities of Fab antibodies in a short period of time. In addition, our laboratory researchers optimize conditions such as induction time, temperature, and reagents to ensure that Fab antibodies are expressed solubly and have antibody activity. We have eukaryotic cell lines, such as mammalian, yeast and insect, that are capable of expressing post-translationally modified Fab antibodies. We will modify and optimize the expression vectors appropriately to improve the expression level and purification efficiency of Fab antibodies.

    Mammalian expression systems usually use transient or stable expression, which can better mimic the expression and modification process of natural proteins, with high efficiency of transcription and translation, and thus enable the production of target proteins with high expression levels. Using mammalian expression systems, such as HEK293 or CHO cell lines, Kamed Bio can prepare Fab antibodies in large quantities by optimizing the culture medium, expression vectors, transfection conditions, etc. for use in drug discovery, biologics and other fields. We will perform quality control and performance verification of the expressed Fab antibodies to ensure that the antibodies have antibody affinity and specificity.