TY - JOUR
T1 - Interactions of bovine brain tubulin with pyridostigmine bromide and N,N'-diethyl-m-toluamide
AU - Prasad, Veena
AU - Scotch, Rebekah
AU - Chaudhuri, Asish Ray
AU - Walss, Consuelo
AU - Fathy, Dana B.
AU - Miller, Claudia
AU - Ludueña, Richard F.
N1 - Funding Information:
Supported by NIH grants GM23476 and CA 26476 and Welch Foundation grant AQ-0726 to R.F.L.
PY - 2000
Y1 - 2000
N2 - Pyridostigmine bromide (PB), an inhibitor of acetylcholinesterase, has been used as a prophylactic for nerve gas poisoning. N,N'-diethyl-m-toluamide (DEET) is the active ingredient in most insect repellents and is thought to interact synergistically with PB. Since PB can inhibit the binding of organophosphates to tubulin and since organophosphates inhibit microtubule assembly, we decided to examine the effects of PB and DEET on microtubule assembly as well as their interactions with tubulin, the subunit protein of microtubules. We found that PB binds to tubulin with an apparent K(d) of about 60 μM. PB also inhibits microtubule assembly in vitro, although at higher concentrations PB induces formation of tubulin aggregates of high absorbance. Like PB, DEET is a weak inhibitor of microtubule assembly and also induces formation of tubulin aggregates. Many tubulin ligands stabilize the conformation of tubulin as measured by exposure of sulfhydryl groups and hydrophobic areas and stabilization of colchicine binding. PB appears to have very little effect on tubulin conformation, and DEET appears to have no effect. Neither compound interferes with colchicine binding to tubulin. Our results raise the possibility that PB and DEET may exert some of their effects in vivo by interfering with microtubule assembly or function, although high intracellular levels of these compounds would be required.
AB - Pyridostigmine bromide (PB), an inhibitor of acetylcholinesterase, has been used as a prophylactic for nerve gas poisoning. N,N'-diethyl-m-toluamide (DEET) is the active ingredient in most insect repellents and is thought to interact synergistically with PB. Since PB can inhibit the binding of organophosphates to tubulin and since organophosphates inhibit microtubule assembly, we decided to examine the effects of PB and DEET on microtubule assembly as well as their interactions with tubulin, the subunit protein of microtubules. We found that PB binds to tubulin with an apparent K(d) of about 60 μM. PB also inhibits microtubule assembly in vitro, although at higher concentrations PB induces formation of tubulin aggregates of high absorbance. Like PB, DEET is a weak inhibitor of microtubule assembly and also induces formation of tubulin aggregates. Many tubulin ligands stabilize the conformation of tubulin as measured by exposure of sulfhydryl groups and hydrophobic areas and stabilization of colchicine binding. PB appears to have very little effect on tubulin conformation, and DEET appears to have no effect. Neither compound interferes with colchicine binding to tubulin. Our results raise the possibility that PB and DEET may exert some of their effects in vivo by interfering with microtubule assembly or function, although high intracellular levels of these compounds would be required.
KW - Microtubule
KW - N,N'-diethyl-m- toluamide
KW - Pyridostigmine
KW - Pyridostigmine bromide
KW - Tubulin
UR - http://www.scopus.com/inward/record.url?scp=0033978976&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0033978976&partnerID=8YFLogxK
U2 - 10.1023/A:1007527129743
DO - 10.1023/A:1007527129743
M3 - Article
C2 - 10685600
AN - SCOPUS:0033978976
SN - 0364-3190
VL - 25
SP - 19
EP - 25
JO - Neurochemical Research
JF - Neurochemical Research
IS - 1
ER -