Biomedical subjects

Hulin Jin

Publications and source records attributed to Hulin Jin.

3 recordsLinked to original sources

PubMed2004

Specific recognition of a dsDNA sequence motif by an immunoglobulin VH homodimer.

Anti-DNA antibodies have the potential to be applied in vast fields of fundamental as well as medical research. They are found in autoimmune diseases, such as systemic lupus erythemotosus. In most cases, anti-dsDNA antibodies do not present sequence specificity and are of low affinity. The dominant role of VH domains in DNA recognition induced us to search for binders based on VH dimers (VHD), previously reported to bind different protein antigens. We screened a phage displayed homo-VHD library against a 19-bp dsDNA sequence. A sequence-specific binder was selected, which recognizes the terminal located CTGC motif with a Kd of 250 nM. Association of the two identical VH domains of the molecule was shown to be essential for binding.

Amino Acid Sequence↗

PubMed2003

Selection and characterisation of binders based on homodimerisation of immunoglobulin V(H) domains.

The antigen-binding surface of antibodies is formed by the heterodimerisation of the two variable domains of the light (V(L)) and heavy (V(H)) chains. We have previously described the spontaneous formation of V(H) dimers (VHD) in both bacteria and mammalian cells. The self-association of a single domain produces a homo-VHD, in which the two identical V(H) domains generate a unique symmetric surface for antigen binding that is never found in the normal V(L)/V(H) antibody binding site. We developed a phagemid vector for the construction of phage display libraries in which a cysteine residue, introduced at the C-terminus of the only V(H) cloned, allowed display of homo-VHDs. Panning of the library on different proteins yielded antigen specific binders against lysozyme, glutathione S-transferase and streptavidin. A lysozyme specific homo-VHD was further characterised with an apparent affinity determined to be 216+/-6.6 nM. Importantly, the results showed that its binding activity was fully dependent on the dimerisation of both identical V(H) domains.

Amino Acid Sequence↗

PubMed2003

Binders based on dimerised immunoglobulin VH domains.

Antibody binding to antigen is mediated by the surface formed by the association of the two variable (V) regions of the L (VL) and H (VH) chains. The capacity of VL to dimerise and the high structural similarity of VL and VH domains suggested the possibility that VH could also associate. We show here that spontaneous formation of VH dimers (VHD) is in many cases permissive, producing stable molecules with antigen binding specificity. VHD were displayed on filamentous phages for the selection of antigen-specific binders. VHD were expressed and secreted efficiently from both bacteria and mammalian cells in different formats, including single-chain (VH(1)-linker-VH(2)), double chain ((VH(2)) and IgG analogues having the VL replaced by VH. The affinity (Kd,app) achieved with a VH dimer expressed in the IgG format, specific for a glutenin subunit was around 30 nM measured by two different methods, which was about 20 times higher than that corresponding to the VL/VH counterpart.

Amino Acid Sequence↗