scFv (single chain variable fragment) consists of the light chain (VL) and heavy chain (VH) variable regions of IgG, connected in the middle by a flexible peptide, and is about 25 kDa in size. scFvs are structurally simple and maintain specificity and affinity for their antigens without the need for constant antibody regions. scFvs have been constructed mainly from hybridoma cells, mouse spleens and human B-lymphocytes. Due to its small size, good tissue permeability, high in vivo clearance and low immunogenicity, it is widely used in the diagnosis and treatment of diseases. In addition, scFv can be expressed in various expression systems by mammalian cells, yeast cells, plant cells and insect cells. Among them, the E. coli expression system is easy to operate, has a short preparation cycle and simple culture conditions, and can be used for the large-scale preparation of scFv antibodies.

    With years of experience in recombinant antibody expression, KMD Bioscience can utilize different protein expression systems for scFv expression according to customer needs. Mammalian expression systems allow for proper folding and post-translational modification of proteins and are the first choice for protein expression in humans or other mammals. However, mammalian expression systems have the disadvantage of low protein yields and require extensive amplification, which will increase the cost and cycle time of experiments. With years of experience in the development of mammalian expression egg systems, KMD Bioscience can provide high-quality scFv eukaryotic expression services. We have the advantage of preparing large quantities of proteins in a short period of time, and can deliver ideal proteins for our clients to use in their functional, structural and therapeutic studies.We not only provide mammalian cell expression system for cells such as CHO and HEK 293, but also provide prokaryotic expression service for E. coli. In addition, we have developed a highly efficient protein soluble expression technology that avoids inclusion body expression of proteins and ensures protein activity, which can be used for large-scale production of scFv antibodies.  KMD Bioscience also has a well-established baculovirus/insect cell protein expression system for the production and expression of viral recombinant proteins from baculovirus-infected insect cells.This expression system facilitates increased protein solubility and post-translational modifications. Meanwhile, the baculovirus/insect cell expression system can express multiple genes at the same time, forming heterodimers or multimers, which can produce higher yields of intracellular and secreted proteins. Our protein expression and purification platforms can be used for both small-scale and large-scale production to meet the diverse needs of our customers. KMD Bioscience can utilize baculovirus expression systems to support the production of difficult to express proteins such as kinases, viral targets, cell surface receptors, transporters, a variety of enzymes, and membrane proteins. We will meet customers' requirements in all aspects, with high quality services throughout the scFv codon optimization and gene synthesis, scFv expression small-scale testing and scale-up, scFv purification and characterization.