A comparative study of inhibition of acetylcholinesterase, trypsin, neuropathy target esterase, and spleen cell activation by structurally related organophosphorus compounds.
Organophosphorus (OP) compounds can bind to and inactivate several target molecules other than acetylcholinesterase (AChE). In the present study, five sets of structurally related organophosphorus compounds were used to evaluate the relationships between organophosphorus binding sites of AChE, neuropathy target esterase (NTE), trypsin, and the target molecule(s) involved in inhibition of splenocyte activation by OP compounds. The concentration of each OP compound required to inhibit enzyme activity or splenocyte activation by concanavalin A by 50% was determined. The pattern of IC50 values indicated that AChE, trypsin, NTE, and the molecule(s) involved in inhibition of splenocyte activation are distinct with regard to patterns of inhibition by OP compounds. However, there was a striking similarity in the patterns of inhibition for trypsin and NTE with substantial differences for only 2 of 20 compounds. This pattern suggests similarity in the active sites of these molecules. There were also similarities in the IC50 patterns for lymphocyte activation and trypsin or NTE activity. However, the correlation was not as strong as between NTE and trypsin, and the data suggested the possibility of multiple target molecules for inhibition of splenocyte activation by OP compounds. More importantly, there was essentially no correlation between the pattern of IC50 values for AChE and splenocyte activation. This strongly suggests that acetylcholine and AChE of the type found in the brain are not important in the regulation of splenocyte activation by concanavalin A.
Pruett
S B
SB
Department of Biological Sciences, Mississippi State University, Mississippi State.
Chambers
H W
HW
Chambers
J E
JE
D000818:Animals; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors*; D002645:Chickens; D002800:Cholinesterase Inhibitors / Q000494:pharmacology*; D005260:Female; D008213:Lymphocyte Activation / Q000187:drug effects; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013053:Spectrophotometry; D013154:Spleen / Q000166:cytology; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000187:drug effects* / Q000502:physiology; D014361:Trypsin Inhibitors / Q000494:pharmacology*
D002800:Cholinesterase Inhibitors; D009943:Organophosphorus Compounds; D014361:Trypsin Inhibitors; D002265:Carboxylic Ester Hydrolases; C021859:neurotoxic esterase