A novel phospholipase C inhibitor, S-PLI produced by Streptomyces sp. strain no. A-6288.
S-PLI, an inhibitor of phospholipase C (PLC) produced by Streptomyces sp. strain No. 6288, was purified from the culture filtrate by salting-out with solid ammonium sulfate, column chromatography on CM-cellulose and gel filtration on Sephadex G-75. The molecular weight of S-PLI was estimated to be 65,000 by SDS-polyacrylamide gel electrophoresis. The inhibitor was found to be a glycoprotein with a composition of 609 amino acids and 19 glucose residues having an isoelectric point at 7.8. S-PLI was stable from pH 3 to 10 at 37 degrees C and up to 40 degrees at pH 6.0. The inhibitory activity showed pH- and temperature-dependence with a maximum around pH 7.0 at 50 degrees C. S-PLI inhibited phospholipase C in a competitive manner (Ki value; 9.5 x 10(-6) mM), but did not inhibit S-Hemolysin, phospholipase A2; phospholipase B, phospholipase D and phosphatases. S-PLI is the first reported example of a glycoproteinaceous inhibitor of microbial origin which is able to specifically inhibit phospholipase C.
Suzuki
K
K
Faculty of Pharmaceutical Science, Kumamoto University, Japan.
Siddique
T
T
Ohya
S
S
Kaneko
M
M
Maruyama
S
S
Shoji
S
S
Uyeda
M
M
D000596:Amino Acids / Q000032:analysis; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D005947:Glucose / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000037:antagonists & inhibitors / Q000187:drug effects; D007526:Isoelectric Point; D007700:Kinetics; D008970:Molecular Weight; D010713:Phosphatidylcholines / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism; D013302:Streptomyces / Q000737:chemistry*; D013696:Temperature; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors* / Q000378:metabolism
D000596:Amino Acids; D003470:Culture Media; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D010713:Phosphatidylcholines; D013109:Sphingomyelins; D006867:Hydrolases; D010738:Type C Phospholipases; D005947:Glucose