Inhibition of brain choline acetyltransferase by tetraplatin.
Tetraplatin inhibited choline acetyltransferase (CAT) from rat and bovine brain with I50 values of 13.5 and 40 microM, respectively. At 0.5 mM concentration, tetraplatin exhibited inhibition of the rat brain enzyme by 89%, whereas cisplatin yielded only 18% inhibition. With bovine CAT, tetraplatin showed noncompetitive inhibition with the substrate choline, Km 337 microM, Ki 29 microM, Vmax 2.83 nmoles acetylcholine formed/min/mg protein, and competitive inhibition with the substrate acetyl-CoA, Km 21 microM, Ki 16 microM, Vmax 3.85 nmoles acetylcholine formed/min/mg protein.
Ho
B T
BT
University of Texas, M.D. Anderson Hospital and Tumor Institute, Houston 77030.
Feiffer
R
R
Tansey
L W
LW
Newman
R A
RA
Fields
W S
WS
Krakoff
I H
IH
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D002795:Choline O-Acetyltransferase / Q000037:antagonists & inhibitors*; D002945:Cisplatin / Q000494:pharmacology; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D009994:Osmolar Concentration; D051381:Rats
D009944:Organoplatinum Compounds; D002795:Choline O-Acetyltransferase; D002945:Cisplatin; C049777:ormaplatin