5.1 The Z domain scaffoldThe work i

5.1 The Z domain scaffold

The work in this thesis is based on the immunotechnological use of affinity ligands

(denoted affibodies) selected from protein libraries based on the so-called Z domain,

utilized as scaffold for library constructions. This Z domain is a 58 aa non-cystein

protein consisting of three anti-parallel α-helices forming a bundle structure. The Z

domain corresponds to an engineered variant of the native B domain of

staphylococcal protein A, in which an Asn28-Gly29 dipeptide sequence, sensitive to

fusion protein cleavage by hydroxylamine, has been changed into an Asn-Ala

sequence. In addition, an alanine residue at position one has been changed into a

valine (Nilsson et al., 1987). This Z domain has been frequently used as affinity

fusion partner for the production of either Z or ZZ-fusion proteins in a number of

different host cells (Ståhl and Nygren, 1997). Utilizing the IgG binding capacity of

the Z domain, such fusion proteins have been possible to recover and immobilize

using IgG-containing matrices or surfaces (Ståhl and Nygren, 1997). The Z domain

has a high solubility, which has been exploited to decrease problems with protein

aggregation during protein refolding procedures (Samuelsson et al., 1991). All the

five native SPA domains show binding to Fc regions of IgG (Moks et al., 1986) and

to antibodies of different isotypes from a number of animal species (Langone, 1982).

In addition, these domains also possess a binding activity towards VH regions of

certain subpopulations of antibodies containing VH regions belonging for example to

the human VHIII family. Recently, data from X-ray diffraction analysis of the co-
crystal complex between the D domain of SPA and a Fab fragment, has shown that

the Fc and VH binding activities are structurally separated and recruit residues of

helices one and two or two and three, respectively (Graille et al., 2000). Assuming a

similar situation also for the other homologous SPA domains, the considerable lower

VH binding demonstrated for the Z domain (Jansson et al., 1998) can be explained by

the Gly29-Ala substitution, corresponding to the introduction of a larger amino acid in

the protein-protein contact surface.

Kết quả (Việt) 1:

5.1 Radio Z domain works in this thesis is based on the use of the relationship immunotechnological ligand (denoted affibodies) protein selected from the library based on the so-called Z domain, used as work stations for library. This domain Z is a non-cysteine ​​58 aa protein consists of three α-helices against parallel structures form a package. Z domain name corresponding to a version of the design of the B domain of native THC protein A, in which Asn28-Gly29 dipeptide sequence, sensitive fusion protein cleavage by hydroxylamine, has been changed to an Asn-Ala sequence. In addition, an alanine residue at position one has is changed to a valine (Nilsson et al., 1987). The domain Z has been used frequently as relationships fusion partner for production or Z or ZZ fusion protein in some Different host cells (Ståhl and Nygren, 1997). Using the ability of the IgG binding Z domain, the fusion protein can be recovered and fixed using a matrix containing antibodies IgG or surface (Ståhl and Nygren, 1997). Domain Z has a high solubility, which has been exploited to reduce the problem to protein aggregation in protein refolding procedures (Samuelsson et al., 1991 ). All five Native Display SPA binding domain to the Fc region of IgG (Moks et al., 1986) and to different antibody isotypes from a number of animal species (Langone, 1982). In addition, the This domain name has a binding activity to the region VH certain populations of antibody VH region belongs example VHIII human family. Recently, data from x-ray diffraction analysis of contraction - crystalline complex between the SPA and the D Fab fragment, showed that the Fc binding activity and VH structure is separated and the residue recruitment of helices one and two or two and three, respectively (Graille et al., 2000). Assuming a similar situation for the similarities SPA other domains, significantly lower than the VH binding domain has been demonstrated to Z (Jansson et al., 1998) have can be explained by the replacement of Gly29-Ala, corresponding to the introduction of a larger amino acids in surface protein-protein contacts.