Asojo OA

References (5)

Title : Cocrystallization studies of full-length recombinant butyrylcholinesterase (BChE) with cocaine - Asojo_2011_Acta.Crystallogr.Sect.F.Struct.Biol.Cryst.Commun_67_434
Author(s) : Asojo OA , Ngamelue MN , Homma K , Lockridge O
Ref : Acta Crystallographica Sect F Struct Biol Cryst Commun , 67 :434 , 2011
Abstract : Human butyrylcholinesterase (BChE; EC 3.1.1.8) is a 340kDa tetrameric glycoprotein that is present in human serum at about 5mgl(-1) and has well documented therapeutic effects on cocaine toxicity. BChE holds promise as a therapeutic that reduces and finally eliminates the rewarding effects of cocaine, thus weaning an addict from the drug. There have been extensive computational studies of cocaine hydrolysis by BChE. Since there are no reported structures of BChE with cocaine or any of the hydrolysis products, full-length monomeric recombinant wild-type BChE was cocrystallized with cocaine. The refined 3 A resolution structure appears to retain the hydrolysis product benzoic acid in sufficient proximity to form a hydrogen bond to the active-site Ser198.
ESTHER : Asojo_2011_Acta.Crystallogr.Sect.F.Struct.Biol.Cryst.Commun_67_434
PubMedSearch : Asojo_2011_Acta.Crystallogr.Sect.F.Struct.Biol.Cryst.Commun_67_434
PubMedID: 21505234
Gene_locus related to this paper: human-BCHE

Title : Five tyrosines and two serines in human albumin are labeled by the organophosphorus agent FP-biotin - Ding_2008_Chem.Res.Toxicol_21_1787
Author(s) : Ding SJ , Carr J , Carlson JE , Tong L , Xue W , Li Y , Schopfer LM , Li B , Nachon F , Asojo OA , Thompson CM , Hinrichs SH , Masson P , Lockridge O
Ref : Chemical Research in Toxicology , 21 :1787 , 2008
Abstract : Tyrosine 411 of human albumin is an established site for covalent attachment of 10-fluoroethoxyphosphinyl- N-biotinamidopentyldecanamide (FP-biotin), diisopropylfluorophosphate, chlorpyrifos oxon, soman, sarin, and dichlorvos. This work investigated the hypothesis that other residues in albumin could be modified by organophosphorus agents (OP). Human plasma was aggressively treated with FP-biotin; plasma proteins were separated into high and low abundant portions using a proteome partitioning antibody kit, and the proteins were digested with trypsin. The FP-biotinylated tryptic peptides were isolated by binding to monomeric avidin beads. The major sites of covalent attachment identified by mass spectrometry were Y138, Y148, Y401, Y411, Y452, S232, and S287 of human albumin. Prolonged treatment of pure human albumin with chlorpyrifos oxon labeled Y138, Y150, Y161, Y401, Y411, and Y452. To identify the most reactive residue, albumin was treated for 2 h with DFP, FP-biotin, chlorpyrifos oxon, or soman, digested with trypsin or pepsin, and analyzed by mass spectrometry. The most reactive residue was always Tyr 411. Diethoxyphosphate-labeled Tyr 411 was stable for months at pH 7.4. These results will be useful in the development of specific antibodies to detect OP exposure and to engineer albumin for use as an OP scavenger.
ESTHER : Ding_2008_Chem.Res.Toxicol_21_1787
PubMedSearch : Ding_2008_Chem.Res.Toxicol_21_1787
PubMedID: 18707141

Title : Crystallization and X-ray structure of full-length recombinant human butyrylcholinesterase - Ngamelue_2007_Acta.Crystallogr.Sect.F.Struct.Biol.Cryst.Commun_63_723
Author(s) : Ngamelue MN , Homma K , Lockridge O , Asojo OA
Ref : Acta Crystallographica Sect F Struct Biol Cryst Commun , 63 :723 , 2007
Abstract : Human butyrylcholinesterase (BChE) has been shown to function as an endogenous scavenger of diverse poisons. BChE is a 340 kDa tetrameric glycoprotein that is present in human serum at a concentration of 5 mg l(-1). The well documented therapeutic effects of BChE on cocaine toxicity and organophosphorus agent poisoning has increased the need for effective methods of producing recombinant therapeutic BChE. In order to be therapeutically useful, BChE must have a long circulatory residence time or associate as tetramers. Full-length recombinant BChE produced in Chinese hamster ovary (CHO) cells or human embryonic kidney cells has been shown to associate as monomers, with a shorter circulatory residence time than the naturally occurring tetrameric serum protein. Based on the preceding observation as well as the need to develop novel methodologies to facilitate the mass production of therapeutic recombinant BChE, studies have been initiated to determine the structural basis of tetramer formation. Towards these ends, full-length monomeric recombinant BChE has been crystallized for the first time. A 2.8 A X-ray structure was solved in space group P42(1)2, with unit-cell parameters a = b = 156, c = 146 A.
ESTHER : Ngamelue_2007_Acta.Crystallogr.Sect.F.Struct.Biol.Cryst.Commun_63_723
PubMedSearch : Ngamelue_2007_Acta.Crystallogr.Sect.F.Struct.Biol.Cryst.Commun_63_723
PubMedID: 17768338
Gene_locus related to this paper: human-BCHE

Title : Role of water in aging of human butyrylcholinesterase inhibited by echothiophate: the crystal structure suggests two alternative mechanisms of aging - Nachon_2005_Biochemistry_44_1154
Author(s) : Nachon F , Asojo OA , Borgstahl GE , Masson P , Lockridge O
Ref : Biochemistry , 44 :1154 , 2005
Abstract : Organophosphorus poisons (OP) bind covalently to the active-site serine of cholinesterases. The inhibited enzyme can usually be reactivated with powerful nucleophiles such as oximes. However, the covalently bound OP can undergo a suicide reaction (termed aging) yielding nonreactivatable enzyme. In human butyrylcholinesterase (hBChE), aging involves the residues His438 and Glu197 that are proximal to the active-site serine (Ser198). The mechanism of aging is known in detail for the nerve gases soman, sarin, and tabun as well as the pesticide metabolite isomalathion. Aging of soman- and sarin-inhibited acetylcholinesterase occurs by C-O bond cleavage, whereas that of tabun- and isomalathion-inhibited acetylcholinesterase occurs by P-N and P-S bond cleavage, respectively. In this work, the crystal structures of hBChE inhibited by the ophthalmic reagents echothiophate (nonaged and aged) and diisopropylfluorophosphate (aged) were solved and refined to 2.1, 2.25, and 2.2 A resolution, respectively. No appreciable shift in the position of the catalytic triad histidine was observed between the aged and nonaged conjugates of hBChE. This absence of shift contrasts with the aged and nonaged crystal structures of Torpedo californica acetylcholinesterase inhibited by the nerve agent VX. The nonaged hBChE structure shows one water molecule interacting with Glu197 and the catalytic triad histidine (His438). Interestingly, this water molecule is ideally positioned to promote aging by two mechanisms: breaking either a C-O bond or a P-O bond. Pesticides and certain stereoisomers of nerve agents are expected to undergo aging by breaking the P-O bond.
ESTHER : Nachon_2005_Biochemistry_44_1154
PubMedSearch : Nachon_2005_Biochemistry_44_1154
PubMedID: 15667209
Gene_locus related to this paper: human-BCHE

Title : Structural data on the aging of diethylphosphoryl-butyrylcholinesterase -
Author(s) : Nachon F , Asojo OA , Borgstahl GE , Masson P , Lockridge O
Ref : Chemico-Biological Interactions , 157-158 :408 , 2005
PubMedID: 16429549