Abstract
Ricin B chain incubated at 37°C in the absence of lactose loses its ability to bind the galactose-containing protein, asialofetuin. Circular dichroism analysis of the B chain thermal denaturation indicates that the loss of galactose-binding ability by the B chain correlates with limited unfolding of the molecule. As a result of this conformational change, disulfide bonds that are shielded from the solvent by the compact folded structure of the B chain become exposed and the chitobiosyl cores of both N-linked oligomannose chains become susceptible to cleavage by endoglycosidases. The heat-denatured B chain does not enhance the toxicity of a ricin A chain-containing rabbit anti-human immunoglobulin (RAHIg-A) to Daudi cells. However, when heat-denatured B chain is coupled to goat anti-rabbit immunoglobulin (GARIg), the resulting immunotoxin, GARIg-hdB, potentiates the killing of RAHIg-A-treated Daudi cells to an extent similar to that of an immunotoxin prepared with GARIg and native B chain. These results indicate that the native, galactose-binding structure of the B chain is not necessary to enhance the cytotoxicity of the cell-reactive A chain immunotoxin (IT-A) and suggests that regions of the B chain exposed by unfolding the molecule may mediate potentiation of cytotoxicity.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 55-62 |
| Number of pages | 8 |
| Journal | BBA - Molecular Cell Research |
| Volume | 971 |
| Issue number | 1 |
| DOIs | |
| State | Published - Aug 19 1988 |
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Keywords
- Galactose binding
- Immunotoxin
- Ricin B chain
ASJC Scopus subject areas
- Biophysics
- Cell Biology
- Molecular Biology
Cite this
Ricin B chain-containing immunotoxins prepared with heat-denatured B chain lacking galactose-binding ability potentiate the cytotoxicity of a cell-reactive ricin A chain immunotoxin. / Wawrzynczak, Edward J.; Drake, Alex F.; Watson, Graham J.; Thorpe, Philip E.; Vitetta, Ellen S.
In: BBA - Molecular Cell Research, Vol. 971, No. 1, 19.08.1988, p. 55-62.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Ricin B chain-containing immunotoxins prepared with heat-denatured B chain lacking galactose-binding ability potentiate the cytotoxicity of a cell-reactive ricin A chain immunotoxin
AU - Wawrzynczak, Edward J.
AU - Drake, Alex F.
AU - Watson, Graham J.
AU - Thorpe, Philip E.
AU - Vitetta, Ellen S.
PY - 1988/8/19
Y1 - 1988/8/19
N2 - Ricin B chain incubated at 37°C in the absence of lactose loses its ability to bind the galactose-containing protein, asialofetuin. Circular dichroism analysis of the B chain thermal denaturation indicates that the loss of galactose-binding ability by the B chain correlates with limited unfolding of the molecule. As a result of this conformational change, disulfide bonds that are shielded from the solvent by the compact folded structure of the B chain become exposed and the chitobiosyl cores of both N-linked oligomannose chains become susceptible to cleavage by endoglycosidases. The heat-denatured B chain does not enhance the toxicity of a ricin A chain-containing rabbit anti-human immunoglobulin (RAHIg-A) to Daudi cells. However, when heat-denatured B chain is coupled to goat anti-rabbit immunoglobulin (GARIg), the resulting immunotoxin, GARIg-hdB, potentiates the killing of RAHIg-A-treated Daudi cells to an extent similar to that of an immunotoxin prepared with GARIg and native B chain. These results indicate that the native, galactose-binding structure of the B chain is not necessary to enhance the cytotoxicity of the cell-reactive A chain immunotoxin (IT-A) and suggests that regions of the B chain exposed by unfolding the molecule may mediate potentiation of cytotoxicity.
AB - Ricin B chain incubated at 37°C in the absence of lactose loses its ability to bind the galactose-containing protein, asialofetuin. Circular dichroism analysis of the B chain thermal denaturation indicates that the loss of galactose-binding ability by the B chain correlates with limited unfolding of the molecule. As a result of this conformational change, disulfide bonds that are shielded from the solvent by the compact folded structure of the B chain become exposed and the chitobiosyl cores of both N-linked oligomannose chains become susceptible to cleavage by endoglycosidases. The heat-denatured B chain does not enhance the toxicity of a ricin A chain-containing rabbit anti-human immunoglobulin (RAHIg-A) to Daudi cells. However, when heat-denatured B chain is coupled to goat anti-rabbit immunoglobulin (GARIg), the resulting immunotoxin, GARIg-hdB, potentiates the killing of RAHIg-A-treated Daudi cells to an extent similar to that of an immunotoxin prepared with GARIg and native B chain. These results indicate that the native, galactose-binding structure of the B chain is not necessary to enhance the cytotoxicity of the cell-reactive A chain immunotoxin (IT-A) and suggests that regions of the B chain exposed by unfolding the molecule may mediate potentiation of cytotoxicity.
KW - Galactose binding
KW - Immunotoxin
KW - Ricin B chain
UR - http://www.scopus.com/inward/record.url?scp=0023694143&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0023694143&partnerID=8YFLogxK
U2 - 10.1016/0167-4889(88)90161-9
DO - 10.1016/0167-4889(88)90161-9
M3 - Article
C2 - 2841982
AN - SCOPUS:0023694143
VL - 971
SP - 55
EP - 62
JO - Biochimica et Biophysica Acta - Molecular Cell Research
JF - Biochimica et Biophysica Acta - Molecular Cell Research
SN - 0167-4889
IS - 1
ER -