The complete amino acid sequence of an abortifacient protein, karasurin.
The complete amino acid sequence of a new abortifacient protein, karasurin, was determined. Karasurin, which was isolated from fresh root tubers of Trichosanthes kirilowii Maximowicz var, japonicum Kitamura (Cucurbitaceae), was a highly basic protein with pI 10.1 and molecular weight of 28,000. Intact karasurin was cleaved with cyanogen bromide, lysyl endopeptidase, formic acid and 2-(2'-nitrophenyl-sulfenyl)-3-methyl-3-bromoindolenine (BNPS-skatole), respectively. Cleavages with N-bromosuccinimide (NBS), trypsin and pepsin were performed for the fragments. The resultant peptide fragments were separated by gel filtration chromatography, reversed-phase high performance liquid chromatography (HPLC) or gel filtration HPLC following sequence analyses by automated Edman methods. Karasurin consists of 246 or 247 amino acid residues with a calculated molecular weight of 27,144 or 27,215 differing only at the C-terminus with the addition of alanyl residue. Two C-terminal sequences were identified as Asn-Asn-Met-OH and Asn-Asn-Met-Ala-OH by sequence analyses and hydrazinolysis, but there was no micro-heterogeneity in other peptides analysed. The sequence of karasurin revealed a considerable similarity to that of trichosanthin and alpha-trichosanthin, which are known as abortifacient, ribosome-inactivating and anti human immunodeficiency virus (HIV) (the virus causing acquired immunodeficiency syndrome (AIDS) proteins, with 93% and 98% identity, respectively.
Toyokawa
S
S
Faculty of Pharmaceutical Sciences, Nagoya City University, Japan.
Takeda
T
T
Kato
Y
Y
Wakabayashi
K
K
Ogihara
Y
Y
D000020:Abortifacient Agents, Nonsteroidal / Q000032:analysis*; D000595:Amino Acid Sequence; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases; D010446:Peptide Fragments / Q000032:analysis; D010940:Plant Proteins / Q000032:analysis*; D015978:Trichosanthin / Q000032:analysis
D000020:Abortifacient Agents, Nonsteroidal; D010446:Peptide Fragments; D010940:Plant Proteins; C069870:karasurin protein, Trichosanthes kirilowii; D015978:Trichosanthin; D009699:N-Glycosyl Hydrolases