Purification and amino acid sequence of a bitter gourd inhibitor against an acidic amino acid-specific endopeptidase of Streptomyces griseus.
An inhibitor (BGIA) against an acidic amino acid-specific endopeptidase of Streptomyces griseus (Glu S. griseus protease) was isolated from seeds of the bitter gourd Momordica charantia L., and its amino acid sequence was determined. The molecular weight of BGIA based on the amino acid sequence was calculated to be 7419. BGIA competitively inhibited Glu S. griseus protease with an inhibition constant (Ki) of 70 nM, and gel filtration analyses suggested that BGIA forms a 1:1 complex with this protease. However, two other acidic amino acid-specific endopeptidases, protease V8 from Staphylococcus aureus and Bacillus subtilis proteinase (Glu B. subtilis protease), were not inhibited by BGIA. BGIA had no inhibitory activity against chymotrypsin, trypsin, porcine pancreatic elastase, and papain, although subtilisin Carlsberg was strongly inhibited. The amino acid sequence of BGIA shows similarity to potato chymotrypsin inhibitor, barley subtilisin-chymotrypsin inhibitor CI-1 and CI-2, and leech eglin C, especially around the reactive site. Although the residue at the putative reactive site of these inhibitors is leucine or methionine, the corresponding amino acid in BGIA is alanine.
Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka, Japan.
F
F
Ogata
T
T
Miyata
N
N
Fujii
N
N
Yoshida
K
K
Noda
S
S
Makisumi
A
A
Ito
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D008969:Molecular Sequence Data; D010455:Peptides / Q000302:isolation & purification* / Q000378:metabolism; D010944:Plants / Q000032:analysis*; D011480:Protease Inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D012639:Seeds / Q000032:analysis; D016415:Sequence Alignment; D012697:Serine Endopeptidases / Q000378:metabolism*; D013305:Streptomyces griseus / Q000201:enzymology*; D013379:Substrate Specificity
D000596:Amino Acids; D005971:Glutamates; D010455:Peptides; D011480:Protease Inhibitors; C070697:BGIA protease inhibitor; D018698:Glutamic Acid; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase