Selection of High Affinity Peptides Against Hepatitis B Core Antigen from a Phage-Displayed Cyclic Peptide Library
Hepatitis B virus is the prototype member of the family Hepadnaviridae which causes acute and chronic liver diseases worldwide. The viral nucleocapsid containing a partially double stranded DNA is surrounded by an envelope comprises three distinct but related surface proteins (HBsAg), termed as s...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2002
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| Online Access: | http://psasir.upm.edu.my/id/eprint/9380/ http://psasir.upm.edu.my/id/eprint/9380/1/FSAS_2002_15_A.pdf |
| _version_ | 1848841130460839936 |
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| author | Ho, Kok Lian |
| author_facet | Ho, Kok Lian |
| author_sort | Ho, Kok Lian |
| building | UPM Institutional Repository |
| collection | Online Access |
| description | Hepatitis B virus is the prototype member of the family Hepadnaviridae which
causes acute and chronic liver diseases worldwide. The viral nucleocapsid
containing a partially double stranded DNA is surrounded by an envelope
comprises three distinct but related surface proteins (HBsAg), termed as small
(S), medium (M) and large (L)-HBsAg. The essential subunit of the nucleocapsid
is a polypeptide comprising 183 amino acids known as core protein (HBcAg).
HBcAg produced in Escherichia coli is capable of self-assembly into core-like
particles and can be purified easily with ammonium sulphate precipitation and
sucrose gradient centrifugation. Core particles make of full-length HB cAg were
used as substrate in biopanning with a cysteine constrained phage-displayed
heptapeptide library. The most frequently identified phage clones displayed the
cyclic peptides C-WSFFS NI-C and C-WPFWGPW-C. The relative dissociation
constant (Krl) values for the interaction between the p hages and HBcAg were
determined by an equilibrium binding assay in solution. The Kiel values for phage bearing peptides C-WSFFSNI-C and C-WPFWGPW-C for full-length and
truncated HBcAg are less than 10 and 30 nM, respectively, which are 17- and 7-
fold stronger than that of phage bearing the l inear peptide LLGRMK. The
selected phages were able to compete with monoclonal antibody C 1-5 for a
binding site on the surface of core particles, suggesting that the docking site of
these phages may partially overlap with the epitope of mAb C 1-5, which was
mapped at amino acid positions 78 to 83 at the tips of the core particles. The
heavy chain of mAb C l-5 is hydrophobic and was proposed to be the contact
region for HBcAg. Interestingly, the isolated peptides C-WSFFS NI-C and
C-WPFWGPW-C are mainly composed of hydrophobic amino acids and may
bind to the same region as mAb C l-5. A synthetic linear peptide bearing the
sequence WSFFSNI inhibited the binding of L-HBsAg to core particles in vitro
with an inhibition concentration (IC₅₀) approximately 9.8 µM. The additional of
cysteine residues to both the N- and C-termini of the peptide greatly reduced the
solubility of this cyclic peptide, and as a result the IC₅₀ is approximately 20-fold
higher than that of WSFFSNI. A suitable recombinant carrier therefore is needed
in order to reduce the hydrophobicity of the peptides and subsequently acts as a
deli very system for targeting the peptide to virally infected cells. |
| first_indexed | 2025-11-15T07:38:21Z |
| format | Thesis |
| id | upm-9380 |
| institution | Universiti Putra Malaysia |
| institution_category | Local University |
| language | English English |
| last_indexed | 2025-11-15T07:38:21Z |
| publishDate | 2002 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | upm-93802013-09-30T08:49:39Z http://psasir.upm.edu.my/id/eprint/9380/ Selection of High Affinity Peptides Against Hepatitis B Core Antigen from a Phage-Displayed Cyclic Peptide Library Ho, Kok Lian Hepatitis B virus is the prototype member of the family Hepadnaviridae which causes acute and chronic liver diseases worldwide. The viral nucleocapsid containing a partially double stranded DNA is surrounded by an envelope comprises three distinct but related surface proteins (HBsAg), termed as small (S), medium (M) and large (L)-HBsAg. The essential subunit of the nucleocapsid is a polypeptide comprising 183 amino acids known as core protein (HBcAg). HBcAg produced in Escherichia coli is capable of self-assembly into core-like particles and can be purified easily with ammonium sulphate precipitation and sucrose gradient centrifugation. Core particles make of full-length HB cAg were used as substrate in biopanning with a cysteine constrained phage-displayed heptapeptide library. The most frequently identified phage clones displayed the cyclic peptides C-WSFFS NI-C and C-WPFWGPW-C. The relative dissociation constant (Krl) values for the interaction between the p hages and HBcAg were determined by an equilibrium binding assay in solution. The Kiel values for phage bearing peptides C-WSFFSNI-C and C-WPFWGPW-C for full-length and truncated HBcAg are less than 10 and 30 nM, respectively, which are 17- and 7- fold stronger than that of phage bearing the l inear peptide LLGRMK. The selected phages were able to compete with monoclonal antibody C 1-5 for a binding site on the surface of core particles, suggesting that the docking site of these phages may partially overlap with the epitope of mAb C 1-5, which was mapped at amino acid positions 78 to 83 at the tips of the core particles. The heavy chain of mAb C l-5 is hydrophobic and was proposed to be the contact region for HBcAg. Interestingly, the isolated peptides C-WSFFS NI-C and C-WPFWGPW-C are mainly composed of hydrophobic amino acids and may bind to the same region as mAb C l-5. A synthetic linear peptide bearing the sequence WSFFSNI inhibited the binding of L-HBsAg to core particles in vitro with an inhibition concentration (IC₅₀) approximately 9.8 µM. The additional of cysteine residues to both the N- and C-termini of the peptide greatly reduced the solubility of this cyclic peptide, and as a result the IC₅₀ is approximately 20-fold higher than that of WSFFSNI. A suitable recombinant carrier therefore is needed in order to reduce the hydrophobicity of the peptides and subsequently acts as a deli very system for targeting the peptide to virally infected cells. 2002-03 Thesis NonPeerReviewed application/pdf en http://psasir.upm.edu.my/id/eprint/9380/1/FSAS_2002_15_A.pdf Ho, Kok Lian (2002) Selection of High Affinity Peptides Against Hepatitis B Core Antigen from a Phage-Displayed Cyclic Peptide Library. Masters thesis, Universiti Putra Malaysia. Peptides Hepatitis B virus English |
| spellingShingle | Peptides Hepatitis B virus Ho, Kok Lian Selection of High Affinity Peptides Against Hepatitis B Core Antigen from a Phage-Displayed Cyclic Peptide Library |
| title | Selection of High Affinity Peptides Against Hepatitis B Core Antigen from a Phage-Displayed Cyclic Peptide Library |
| title_full | Selection of High Affinity Peptides Against Hepatitis B Core Antigen from a Phage-Displayed Cyclic Peptide Library |
| title_fullStr | Selection of High Affinity Peptides Against Hepatitis B Core Antigen from a Phage-Displayed Cyclic Peptide Library |
| title_full_unstemmed | Selection of High Affinity Peptides Against Hepatitis B Core Antigen from a Phage-Displayed Cyclic Peptide Library |
| title_short | Selection of High Affinity Peptides Against Hepatitis B Core Antigen from a Phage-Displayed Cyclic Peptide Library |
| title_sort | selection of high affinity peptides against hepatitis b core antigen from a phage-displayed cyclic peptide library |
| topic | Peptides Hepatitis B virus |
| url | http://psasir.upm.edu.my/id/eprint/9380/ http://psasir.upm.edu.my/id/eprint/9380/1/FSAS_2002_15_A.pdf |