Biomedical subjects

Wen Hui Lee

Publications and source records attributed to Wen Hui Lee.

6 recordsLinked to original sources

PubMed2003

Bombinakinin M gene associated peptide, a novel bioactive peptide from skin secretions of the toad Bombina maxima.

A novel 28-amino acid peptide, termed bombinakinin-GAP, was purified and characterized from skin secretions of the toad Bombina maxima. Its primary structure was established as DMYEIKQYKTAHGRPPICAPGEQCPIWV-NH(2), in which two cysteines form a disulfide bond. A FASTA search of SWISS-PROT databank detected a 32% sequence identity between the sequences of the peptide and a segment of rat cocaine- and amphetamine-regulated transcript (CART). Intracerebroventricular (i.c.v.) administration of the peptide induced a significant decrease in food intake in rats, suggesting that it played a role in the control of feeding by brain. Analysis of its cDNA structure revealed that this peptide is coexpressed with bombinakinin M, a bradykinin-related peptide from the same toad. Bombinakinin-GAP appears to be the first example of a novel class of bioactive peptides from amphibian skin, which may be implicated in feeding behavior.

Amino Acid Sequence↗

PubMed2003

Two novel Bv8-like peptides from skin secretions of the toad Bombina maxima.

Two novel bioactive peptides were purified from skin secretions of the toad Bombina maxima. The partial N-terminal sequences of these two peptides were determined by automated Edman degradation. This allowed the cloning of full-length cDNAs encoding these two peptides from a cDNA library prepared from the toad skin. The deduced complete amino acid sequences indicate that both peptides are composed of 77 amino acids. A FASTA search in the databanks revealed that they exhibit 86-91% sequence identity with Bv8, a peptide originally isolated from skin secretions of Bombina variegata. They were thus named as Bv8-like peptide 1 (Bv8-LP1) and Bv8-like peptide 2 (Bv8-LP2), respectively. Sequence differences between Bv8-LP1 and 2 were due to six amino acid substitutions at positions 6, 11, 23, 24, 62 and 63. Bv8-LP1 and 2 differed from Bv8 with eleven and seven amino acid substitutions, respectively. Like Bv8, Bv8-LP1 and 2 possessed contractile activity on isolated guinea pig ileum. Additionally, they stimulated contraction of rabbit aortic rings in a dose-dependent manner at nanomolar concentrations.

Amino Acid Sequence↗

PubMed2002

An anionic antimicrobial peptide from toad Bombina maxima.

Amphibian skin is a rich resource of antimicrobial peptides like maximins and maximins H from toad Bombina maxima. A novel cDNA clone encoding a precursor protein that comprises maximin 3 and a novel peptide, named maximin H5, was isolated from a skin cDNA library of B. maxima. The predicted primary structure of maximin H5 is ILGPVLGLVSDTLDDVLGIL-NH2. Containing three aspartate residues and no basic amino acid residues, maximin H5 is characterized by an anionic property. Different from cationic maximin H peptides, only Gram-positive strain Staphylococcus aureus was sensitive to maximin H5, while the other bacterial and fungal strains tested were resistant to it. The presence of metal ions, like Zn2+ and Mg2+, did not increase its antimicrobial potency. Maximin H5 represents the first example of potential anionic antimicrobial peptides from amphibians. The results provide the first evidence that, together with cationic antimicrobial peptides, anionic antimicrobial peptides may also exist naturally as part of the innate defense system.

Amino Acid Sequence↗

PubMed2002

Antimicrobial peptides from skin secretions of Chinese red belly toad Bombina maxima.

Two groups of antimicrobial peptides have been isolated from skin secretions of Bombina maxima. Peptides in the first group, named maximins 1, 2, 3, 4 and 5, are structurally related to bombinin-like peptides (BLPs). Unlike BLPs, sequence variations in maximins occurred all through the molecules. In addition to the potent antimicrobial activity, cytotoxicity against tumor cells and spermicidal action of maximins, maximin 3 possessed a significant anti-HIV activity. Maximins 1 and 3 were toxic to mice with LD(50) values of 8.2 and 4.3 mg/kg, respectively. Peptides in the second group, termed maximins H1, H2, H3 and H4, are homologous with bombinin H peptides. cDNA sequences revealed that one maximin peptide plus one maximin H peptide derived from a common larger protein.

Amino Acid Sequence↗

PubMed2002

A novel proline rich bombesin-related peptide (PR-bombesin) from toad Bombina maxima.

A novel bombesin-related peptide was isolated from skin secretions of Chinese red belly toad Bombina maxima. Its primary structure was established as pGlu-Lys-Lys-Pro-Pro-Arg-Pro-Pro-Gln-Trp-Ala-Val-Gly-His-Phe-Met-NH(2.) The amino-terminal (N-terminal) 8-residue segment comprising four prolines and three basic residues is extensively different from bombesins from other Bombina species. The peptide was thus named proline rich bombesin (PR-bombesin). PR-bombesin was found to elicit concentration-dependent contractile effects in the rat stomach strip, with both increased potency and intrinsic activity as compared with those of [Leu(13)]bombesin. Analysis of different bombesin cDNA structures revealed that an 8 to 14- nucleotide fragment replacement in the peptide coding region (TGGGGAAT in the cDNAs of multiple bombesin forms from Bombina orientalis and CACCCCGGCCACCC in the cDNA of PR-bombesin) resulted in an unusual Pro-Pro-Arg-Pro-Pro motif in the N-terminal part of PR-bombesin.

Amino Acid Sequence↗

PubMed2002

Identification and cloning of a trypsin inhibitor from skin secretions of Chinese red-belly toad Bombina maxima.

A novel trypsin inhibitor was identified and purified from skin secretions of Chinese red-belly toad Bombina maxima. The partial N-terminal 29 amino acid residues of the peptide, named BMTI, were determined by automated Edman degradation. This allowed the cloning of a full-length cDNA encoding BMTI from a cDNA library prepared from the toad skin. The deduced complete amino acid sequence of BMTI indicates that mature BMTI is composed of 60 amino acids. A FASTA search in the databanks revealed that BMTI exhibits 81.7% sequence identity with BSTI, a trypsin/thrombin inhibitor from European toad Bombina bombina skin secretions. Sequence differences between BMTI and BSTI were due to 11 substitutions at positions 2, 9, 25, 27, 36-37, 39, 41-42, 50 and 56. BMTI potently inhibited trypsin with a K(i) value of 0.06 microM, similar to that of BSTI. However, unlike BSTI, which also inhibited thrombin with a K(i) value of 1 microM, no inhibitory effect of BMTI on thrombin was observed under the assay conditions.

Amino Acid Sequence↗