碘解磷定对胆碱酯酶复活和抑制作用的研究

目的　研究碘解磷定对胆碱酯酶复活和抑制双向作用。方法　Hestrin法测定胆碱酯酶活性 ,离体实验和在体实验研究碘解磷定对未被和已被DDVP抑制的胆碱酯酶的作用和量效关系。结果　离体实验 1 0mmol·L-1以上浓度的碘解磷定对小鼠胆碱酯酶有抑制作用 ,且呈量效关系 ;对被敌敌畏抑制的小鼠胆碱酯酶有双向作用 ,该作用与碘解磷定的量和胆碱酯酶被抑制程度有关 ,胆碱酯酶抑制较重时 ,碘解磷定能使之复活 ,抑制较轻时则加重其抑制。在体实验仅当PAM剂量高达 30 0mg·kg-1(相当于 1 34LD50 )时才对小鼠血胆碱酯酶轻度抑制。对敌敌畏中毒小鼠 ,10～15 0mg·kg-1的DDVP中毒抑制的胆碱酯酶有复活作用且呈量效关系。结论　非致死量的碘解磷定对在体胆碱酯酶无抑制作用。     

离子色谱法测定氯化琥珀胆碱原料及注射液中的氯化胆碱和氯化琥珀酰单胆碱

目的 采用离子色谱法测定氯化琥珀胆碱原料及注射液中的氯化胆碱和氯化琥珀酰单胆碱。方法 采用Dionex RFICTM Ionpac CS17色谱柱（4 mm×250 mm）,以甲烷磺酸溶液为流动相进行梯度洗脱,流速为1.0 mL·min^-1,采用抑制电导检测器进行测定。结果 氯化胆碱、氯化琥珀酰单胆碱浓度分别在18.0~562.8 μg·mL^-1（r=0.999 9）和14.4~449.8 μg·mL^-1（r=0.999 9）内线性关系良好,定量限均为0.01 μg·mL^-1。原料中氯化胆碱、氯化琥珀酰单胆碱回收率分别为103.4%~105.7%和102.4%~107.1%;注射液中氯化胆碱、氯化琥珀酰单胆碱回收率分别为95.6%~100.2%和94.4%~103.5%。结论 该方法专属性强、准确、简便、快速,适用于氯化琥珀胆碱原料及制剂中的有关物质测定。     

Characteristics of recombinant human butyrylcholinesterase 1

目的：研究重组人丁酰胆碱酯酶（ｒｈＢＣｈＥ）的生化药理学性质,探讨其做为琥珀酰胆碱中毒解毒剂的可行性．方法：中国仓鼠卵巢细胞用电击法转染质粒,ＤＴＮＢ法测定ＢＣｈＥ活性,酶联免疫吸附试验和蛋白质印迹检测抗原性．结果：ｒｈＢＣｈＥ最高表达水平为每１０６细胞２５８３ｎｇ·ｈ－１．ｒｈＢＣｈＥ的底物亲和力、对抑制剂的敏感性、被抑制后的可重活化性、稳定性及与抗体的反应性等性质与天然ＢＣｈＥ（ｎｈＢＣｈＥ）极为相似．１５个致死量的琥珀酰胆碱经ｒｈＢＣｈＥ体外解毒后,注射小鼠未出现任何中毒症状．结论：ｒｈＢＣｈＥ和ｎｈＢＣｈＥ的生化药理学性质极为相似,ｒｈＢＣｈＥ具有潜在实用价值     

全氟异丁烯中毒耐受小鼠的肺表面活性物质含量的变化

目的　通过观察肺组织中的二棕榈酰磷脂酰胆碱 (dipalmitoylphosphatidylcholine ,DPPC)含量的变化 ,反映肺表面活性物质 (pulmonarysurfactant,PS)的含量与小鼠对全氟异丁烯 (perfluoroisobutylene ,PFIB)中毒耐受性的关系 ,以揭示小鼠对PFIB中毒耐受的机制。方法　采用静式全暴露法 ,分别以 710、775和 12 5 0 μg (L·min) 浓度的PFIB 3次染毒小鼠。用干湿重法测定每次中毒后活存小鼠的肺水含量 ,并采用高效液相色谱法 (HPLC)测定其肺组织磷脂中DPPC的含量。结果　 (1)第 2次中毒和第 3次中毒小鼠的活存率均明显高于其对照组 (P <0 0 1) ;(2 )耐受PFIB小鼠的肺水含量与正常对照组相比没有差别 ;(3 )中毒耐受小鼠的肺组织中DPPC含量均明显高于对照组 (P <0 0 5或P <0 0 1)。结论　急性低浓度PFIB重复中毒的小鼠在致死剂量PFIB染毒时没有出现死亡 ,其肺组织中DPPC的含量较正常对照组显著增高 ,提示实验动物对急性PFIB中毒的耐受性与PS含量的增多有相关性     

普伐他汀对溶血磷脂酰胆碱促血管平滑肌细胞增殖及细胞粘附的影响

目的　探讨羟甲基戊二酰辅酶A还原酶抑制剂普伐他汀对溶血磷脂酰胆碱 (LPC)促血管平滑肌细胞增殖及白细胞与内皮细胞粘附的影响。方法　用MTT法检测LPC对平滑肌细胞增殖的量效和时效关系及普伐他汀对LPC促平滑肌细胞增殖的影响 ;用直接记数法检测LPC诱导中性粒细胞系K5 6 2细胞与人脐静脉内皮细胞系ECV30 4细胞的粘附和普伐他汀对LPC所致白细胞与内皮细胞粘附的影响。结果　用 1～ 10 μmol·L-1LPC孵育血管平滑肌细胞 2 4～ 4 8h后 ,呈时间和剂量依赖性地诱导细胞增殖 ,而用 0 3～ 1mmol·L-1普伐他汀预孵育平滑肌细胞 1h ,再与 3μmol·L-1LPC共孵育 2 4～ 4 8h ,明显地抑制LPC所诱导的细胞增殖 ;用 3μmol·L-1LPC孵育ECV30 4细胞 12h显著增加K5 6 2细胞与ECV30 4细胞的粘附 ,而将ECV30 4细胞用 1mmol·L-1普伐他汀预处理后 ,明显减少白细胞与内皮细胞的粘附。结论　普伐他汀可抑制LPC促血管平滑肌细胞增殖及白细胞与内皮细胞粘附的作用。     

卡托普利抗同型半胱氨酸和溶血性磷脂酰胆碱损伤大鼠血管内皮功能

目的　研究卡托普利能否保护同型半胱氨酸(Hcy)和溶血性磷脂酰胆碱 (LPC)在体外直接损伤的大鼠离体胸主动脉内皮功能。方法　用Hcy或LPC孵育大鼠离体胸主动脉环 3 0min诱导血管内皮损伤 ,观察卡托普利对Hcy和LPC损伤血管内皮依赖性舒张反应的影响。结果　Hcy( 0 .3～ 3mmol·L-1)或LPC( 1～1 0 μmol·L-1)呈浓度依赖性地损伤乙酰胆碱诱导的内皮依赖性血管舒张反应 ,但不影响硝普钠诱导的内皮非依赖性血管舒张。卡托普利( 3～3 0 μmol·L-1)预孵育血管环 1 5min,再与Hcy( 1mmol·L-1)共同孵育 3 0min,浓度依赖性改善Hcy对血管内皮依赖性舒张反应的损害。 3 0 μmol·L-1卡托普利也可完全逆转LPC( 3 μmol·L-1)对内皮依赖性血管舒张反应的损害。结论　卡托普利对Hcy和LPC所引起的血管内皮依赖性舒张反应的损害都具有明显的保护作用     

高效液相色谱法测定多烯磷脂酰胆碱软胶囊中磷脂酰胆碱和溶血磷脂酰胆碱的含量

目的建立HPLC法测定多烯磷脂酰胆碱软胶囊中磷脂酰胆碱和溶血磷脂酰胆碱的含量以及有关物质方法。方法采用蒸发光散射检测器SEDEX55,MERCK的Li Chrospher 100 Diol-5色谱柱(125mm×4.0 mm,5μm);流动相A为正己烷-异丙醇-冰醋酸-三乙胺(814∶170∶15∶0.8),流动相B为异丙醇-超纯水-冰醋酸-三乙胺(844∶140∶15∶0.8),梯度洗脱。结果磷脂酰胆碱在0.912~2.736mg·mL~(-1),溶血磷脂酰胆碱在0.072~0.216 mg·mL~(-1)内与峰面积线性关系良好(R~2均为0.999)。磷脂酰胆碱的平均回收率为101.2%,RSD为1.3%;溶血磷脂酰胆碱的平均回收率为100.5%,RSD为1.9%。溶血磷脂酰胆碱的检测限为0.57μg。结论本检测方法专属性强,结果可靠,专属性强,重复性良好,可用于多烯磷脂酰胆碱软胶囊的质量评价。     

去甲基斑蝥素N-乳糖酰壳聚糖纳米粒的吸收机制及小鼠抑瘤作用研究

目的:研究去甲基斑蝥素N-乳糖酰壳聚糖纳米粒(NCTD-GC-NPs)的吸收机制和小鼠抑瘤作用。方法:以表观透过系数为指标,考察NCTD-GC-NPs(80μg·mL-1)及其分别与环孢素A(50μmol·L-1)、去氧胆酸钠(100mmol·L-1)、叠氮化钠(25mmol·L-1)、氧化苯胂(25mmol·L-1)联用后对结肠癌Caco-2细胞转运的影响;将接种肝癌细胞H22后的小鼠随机分为空白组、对照组(NCTD原料药2mg·kg-1)和NCTD-GC-NPs低、中、高剂量组(0.5、2、4mg·kg-1),每组10只,每日灌胃给药1次,连续给药8d,考察各组小鼠体重和抑瘤率。结果:环孢素A、去氧胆酸钠和叠氮化钠均能明显促进NCTD-GC-NPs在Caco-2细胞的转运(P<0.05或P<0.01),氧化苯胂对转运无明显影响;各组小鼠体重无明显变化;与对照组比较,NCTD-GC-NPs中、高剂量组的抑瘤率明显增强(P<0.05或P<0.01)。结论:NCTD-GC-NPs主要通过主动转运穿过小肠上皮细胞,能明显抑制肝癌肿瘤细胞H22的生长。     

鬼臼酰肼-2,2,6,6-四甲基哌啶腙的抗肿瘤作用

目的研究鬼臼酰肼-2，2，6，6-四甲基哌啶腙的抗肿瘤作用。方法：K(562)及L(1210)细胞体外培养24h台盼蓝染色计数、小鼠单次腹腔注射LD(50)测定、小鼠移植性肿瘤S(180)、EAC及HepA皮下接种及测瘤重。结果：鬼臼酰肼-2，2，6，6-四甲基哌啶腙及鬼臼乙叉甙用0．1714、0．0857、0.0171、0.0086及0.0017mmol·L(－1)浓度对体外培养的K(562)及L(1210)细胞有杀伤及增殖抑制作用，鬼臼酰肼-2，2，6，6-四甲基哌啶腙的抑制率为60．55％、45．38％、18．68％、15．93％、11．57％；61．88％、47．59％、24．28％、16．55％、12．85％。鬼臼乙叉甙抑制率为64．73％、49．15％、22．94％、15．37％、10．44％；66．37％、52．43％、36.32％、19．37％、9．07％，给药组与对照组比较差别有显著性。两药品相同剂量比较无明显的差异，鬼臼酰肼-2,2，6，6-四甲基哌啶腙小鼠单次腹腔注射LD(50)为288．6～413．1mg·kg(-1)。鬼臼乙叉甙LD50为72.3～102.9mg·kg(-1)，对小鼠移植性肿瘤S(180)、EAC及HepA有抑制作用，瘤重抑制率鬼臼酰肼-2，2，6，6-四甲基哌啶腙为41．6％、43．3％、40．3％、（70．0mg·kg(－1)），32．2％、34．6％、35．1％（35．0mg·kg(-1)），26.2％、32.3％、28．6％（14．5mg·kg(－1)）;鬼臼乙叉?     

还原型谷胱甘肽与多烯磷脂酰胆碱对环磷酰胺诱导小鼠肝损伤的修复作用

目的：分析比较还原型谷胱甘肽与多烯磷脂酰胆碱对环磷酰胺诱导小鼠肝损伤的防护作用。方法采用简单随机抽样法将40只昆明小鼠分为肝损伤模型组、还原型谷胱甘肽组、多烯磷脂酰胆碱组和对照组,每组10只。前3组小鼠实验第1-4天均腹腔注射环磷酰胺（100 mg· kg-1·d-1）诱导肝损伤,第5-14天分别腹腔注射0.9%氯化钠注射液0.2 ml、还原型谷胱甘肽180 mg · kg-1· d-1、多烯磷脂酰胆碱90 mg·kg-1·d-1;对照组同期腹腔注射等体积0.9%氯化钠注射液。实验第1天给药前和第15天测定小鼠体重;实验第15天,小鼠处死前眼眶取血测定血清总胆红素和谷胱甘肽水平,处死小鼠后取肝脏称重并计算肝脏系数,取肝组织测定丙氨酸转氨酶（ ALT）、天冬氨酸转氨酶（AST）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性和丙二醛（MDA）水平,并进行肝组织形态学观察。结果实验第15天,应用环磷酰胺的3组小鼠体重均明显低于对照组（P 〈0.01或 P 〈0.05）,但还原型谷胱甘肽组体重高于肝损伤模型组（P 〈0.05）;肝损伤模型组小鼠肝脏系数（5.74%±0.11%）高于对照组（4.68%±0.37%）和还原型谷胱甘肽组（4.81%±0.19%）（均 P 〈0.01）,多烯磷脂酰胆碱组小鼠肝脏系数（5.25%±0.35%）]也高于对照组（P 〈0.05）。肝损伤模型组、还原型谷胱甘肽组、多烯磷脂酰胆碱组血清总胆红素水平[（129.8±1.9）、（110.9±1.3）、（125.7±2.6）μmol/ L]均高于对照组（100.8±3.0）μmol/ L（均 P 〈0.01）,但还原型谷胱甘肽组低于肝损伤模型组（P 〈0.01）。肝损伤模型组和多烯磷脂酰胆碱组血清谷胱甘肽水平[（50.5±1.9）、（55.9±2.4）g/ L]均低于对照组和还原型谷胱甘肽组[（73.8±4.3）、（71.3±3.7）g/ L]（均 P 〈0.01）。肝损伤模型组、还原型谷胱甘肽组、多烯磷脂酰胆碱组肝组织 AST、ALT、SOD 和 CAT ?     

High-level expression of human butyrylcholinesterase gene in Bombyx mori and biochemical-pharmacological characteristic study of its product

The human butyrylcholinesterase (BChE, EC 3.1.1.8) gene was highly expressed in Bombyx mori using baculovirus vector, and the biochemical-pharmacological properties of its product were studied. BChE cDNA was cloned into transfer vector pBn96 and co-transfected with wild-type Bombyx mori nucleopolyhedrovirus (BmNPV) DNA into BmN cells. The recombinant virus with the highest enzyme activity was sorted out and purified. Once the BmN cells or silkworm larvae had been infected with the recombinant virus, recombinant human BChE (rhBChE) could be secreted into the culture medium or the hemolymph of the larvae at levels of 1.5 mg x L(-1) and 35 mg x L(-1), respectively. Western blot and enzymatic staining of the electrophoresis gel of non-denatured protein showed that rhBChE manifested similar antigenicity and enzyme activity to native human BChE (nhBChE). The production of rhBChE in the hemolymph was 23-fold higher than that in BmN cells and about 280-fold that in Chinese hamster overy cells (125 microg x L(-1)). This is the first report of human BChE expression in silkworm with the highest level of yield so far. rhBChE was highly similar to nhBChE in respect to substrate affinity, inhibitor sensitivity, and reactivity of the inhibited enzyme. It is suggested that rhBChE functions as well as nhBChE and has potential practical value.     

重组人丁酰胆碱酯酶的特性

AIM: To study the biochemical-pharmacological properties of the recombinant human butyrylcholinesterase (rhBChE) and thereby to size up the potential possibility of using it as a detoxifying agent in succinylcholine intoxication. METHODS: CHO-dhfr cells were transfected with plasmids by electroporation. BChE activity was determined colorimetrically by 5, 5'-dithiobis-(2-nitrobenzoic acid) (DTNB) method. Antigenicity was estimated by enzyme-linked immunosorbent assay and Western blot. RESULTS: The maximal expression amounted to 25.83 ng.h-1/10(6) cells. The rhBChE was highly similar to the native human BChE (nhBChE) in terms of its catalytic property, substrate affinity, inhibitor sensitivity, reactivation, stability, and immunoreactivity with anti-nhBChE antibodies. Mice challenged with 1.5 lethal dose of succinylcholine preincubated with rhBChE survived without any symptoms of intoxication. CONCLUSION: The rhBChE and nhBChE exhibit similar biochemical-pharmacological features. It is of potential value in practical use.     

Two novel mutations in the BCHE gene in patients with prolonged duration of action of mivacurium or succinylcholine during anaesthesia

BACKGROUND: Butyrylcholinesterase (BChE) hydrolyses the neuromuscular blocking agents, succinylcholine and mivacurium used during general anaesthesia. Hereditary low BChE activity may result in an extensively prolonged duration of action of these drugs, especially in patients who are homozygous for the atypical or silent variants. We present three novel mutations in the butyrylcholinesterase gene (BCHE) identified in three families in which a member had experienced severely prolonged duration of action of succinylcholine. METHODS: As the phenotypes of the three probands could not be established with certainty using conventional biochemical tests, DNA samples were collected from two of the probands and four relatives. Genotypes were determined using complete nucleotide sequencing. RESULTS: Three novel mutations were identified: BCHE*FS126, BCHE*I3E4-14C and BCHE*328D. The proband in family 1 was genotyped as BCHE*115D*I3E4-14C/BCHE*FS126, whereas the proband in family 3 was compound heterozygous for BCHE*328D and BCHE*142M. In both patients, BChE activity was below detection limit, and they experienced an extensively prolonged duration of action of succinylcholine. The proband in family 2 was not sequenced, but a relative was heterozygous for BCHE*FS126. BCHE*I3E4-14C was in linkage with a known silent variant. CONCLUSIONS: Two novel variants of BCHE are silencing the enzyme function. BCHE*FS126 results in a truncated protein lacking the active site and is therefore inactive. The second variant is BCHE*328D, also resulting in an inactive protein, as this change in amino acid is radical and furthermore situated in the gorge harbouring the active site. These variants result in extensively prolonged duration of action of succinylcholine.     

系统进化指数富集法筛选抑制人乙酰胆碱酯酶的RNA分子

目的：获得针对人红细胞乙酰胆碱酯酶(AChE)的特异性核酸配基．方法：利用微孔板法筛选人红细胞膜AChE的核酸配基．利用凝胶阻滞实验检测核酸配基与AChE特异性的结合．微量碱羟胺比色法测定AChE的活性．结果：经过9轮筛选得到针对人红细胞AChE的核酸配基．在相同浓度(2．25μmol/L)下,它们不与人重组丁酰胆碱酯酶(rhBChE)作用,而与人RBCAChE特异结合并抑制AChE的活性．结论：用SELEX技术可以高效地从大容量寡核苷酸组合文库中得到AChE特异性抑制剂．     

Inhibitory effect of reactive oxygen species on angiotensin I-converting enzyme (kininase II)

1. Somatic angiotensin I-converting enzyme (ACE) is a protein that contains two similar domains (N- and C-terminal), each possessing an active site. We have examined the effects of a generator of hydroxyl radicals (g*OH: 2,2'-azo-bis(2-amidinopropane)) and hydrogen peroxide (H2O2) on ACE using an in vitro approach. 2. The generator of hydroxyl radicals inactivated ACE in a time (2-6 h)- and concentration (0.3-3 mmol/L)-dependent manner at 37 degrees C. When ACE was coincubated for 4 h with g*OH (3 mmol/L), its activity decreased by 70%. Addition of dimethylthiourea or mannitol + methionine, two *OH scavengers, resulted in a significant protection of ACE activity. Mercaptoethanol and dithiotreitol, two thiol-reducing agents, also efficiently protected ACE activity. 3. The hydrolysis of two natural and domain-specific substrates was explored. The hydrolysis of angiotensin I, preferentially cleaved by the C-domain, was significantly inhibited (57-58%) after 4 h exposure to g*OH (0.3-1 mmol/L). Under the same conditions of exposure, the hydrolysis of N-acetyl-Ser-Asp-Lys-Pro, a specific substrate for the N-domain, was only slightly inhibited by 1 mmol/L g*OH. 4. Hydrogen peroxide, another source of *OH, was used. After exposure to H2O2 (3 mmol/L; 4 h), an 89% decrease in ACE activity was observed. Pretreatment with the iron chelator deferoxamine (1 mmol/L) attenuated H2O2-mediated ACE inactivation, demonstrating that the effect of H2O2 was partly due to its conversion into *OH (Fenton reaction). 5. In summary, our findings demonstrate that g*OH and H2O2 inhibit ACE activity and suggest a preferential action of g*OH on the C-domain of the enzyme.     

Anti-epitope antibody, a novel site-directed antibody against human acetylcholinesterase

AIM: To construct synthetic antigens using the epitope of human brain acetylcholinesterase (hbAChE) for induc- tion and detection of the specific antibody against the epitope, and to analyse the immunogenicity of the antibody. METHODS: The epitope (RTVLVSMNYR, amino acids 143-152) of hbAChEwas chemically synthesized, coupled with the carrier protein keyhole limpet hemocyanin (KLH) to construct an artificial immunogen (KLH-epitope), and injected into rabbits to raise antibody. T…     

Production and characterization of separate monoclonal antibodies to human acetylcholinesterase and butyrylcholinesterase

Butyrylcholinesterase purified from human plasma and acetylcholinesterase purified from human red blood cells were used to immunize separate groups of BALB/c mice. A solid-phase immunoadsorbance assay was developed to screen and characterize antibodies specific for the cholinesterases. Immunized spleen cells were fused with a non-immunoglobulin-secreting myeloma cell line (FO). After two subcultures at limiting dilution, several clones secreting antibodies to acetylcholinesterase or butyrylcholinesterase were obtained. Selected clones were expanded as ascites tumors in immunosuppressed BALB/c mice. All tested immunoglobulins consisted of kappa light chains and either G1 or G2b heavy chains. Two-dimensional gel electrophoresis confirmed the monoclonal nature of each isolated antibody. None of the antibodies to acetylcholinesterase cross-reacted with butyrylcholinesterase, and vice versa. All tested antibodies exhibited high avidity for human enzyme, independent of the tissue source (apparent dissociation constants: 1-3 nM for acetylcholinesterase antibodies; 2-13 nM for butyrylcholinesterase antibodies). Treatment of enzymes with monoclonal antibodies increased the sedimentation coefficients (from 6.5 S to 12 S for acetylcholinesterase, from 11 S to 18 S or 20 S for butyrylcholinesterase). All of the monoclonal antibodies displayed marked species specificity. Several antibodies reacted only with human enzyme; others reacted with enzyme from nonhuman primates as well. A few of the butyrylcholinesterase antibodies cross-reacted weakly with enzyme from dog, cat, and horse, but none reacted with the enzyme from rat, guinea pig, and chicken. One acetylcholinesterase antibody cross-reacted with acetylcholinesterase of rabbit and guinea pig. The avidity, species selectivity, and other properties of these antibody reagents will be useful in future studies on the regulation and disposition of cholinesterases.     

Structural basis of the butyrylcholinesterase H-variant segregating in two Danish families.

The rare H-variant of human butyrylcholinesterase is a quantitative variant that reduces serum butyrylcholinesterase activity by about 90%. Individuals who are heterozygous for both the H-variant and the atypical variant are abnormally sensitive to the muscle relaxant succinylcholine. By using standard phenotypic serum assays, the Danish Cholinesterase Research Unit identified four individuals from two unrelated pedigrees who were heterozygous for both the H-variant (H) and the atypical (A) variant. DNA of these A/H individuals was extracted from white blood cells. Using the polymerase chain reaction and subsequent DNA sequencing, a point mutation was found at nucleotide 424 which changed amino acid 142 from valine to methionine. The previously identified atypical mutation, Asp 70 to Gly, was also seen, which segregated apart from the H-variant mutation in family studies. These two mutations were found in all four A/H individuals.     

人肝梭曼水解酶的微量比色测定及性质

建立了人肝二异丙基氟磷酸酯酶（ＤＦＰａｓｅ，ＥＣ．３．１．８．２．）的微量比色测定法并探讨了此酶的部分生化性质。梭曼在过硼酸钠及丙酮存在时，可与盐酸联苯胺反应生成橙黄色偶氮化合物，橙黄色产物的量与梭曼量在１０－２００ｎｍｏｌ范围内呈正相关。本文将此呈色反应与酶反应相结合，通过测定剩余梭曼的量来测定酶活力，并探讨了测定的最适条件。测定的变异系数为５％，测得人肝ＤＦＰａｓｅ的Ｋｍ值为３ｍｍｏｌ·Ｌ－１，最适ｐＨ范围为７．０－７．２，酶反应时间为２５ｍｉｎ，在－２０℃保存７个月，或在３７℃保温１８ｈ活性无明显丧失，反复冻融３次活性不变，但经冻融６次时活性下降１／５．人肝ＤＦＰａｓｅ活性主要存在于细胞的可溶性部分。     

Epoxide hydrolase in human fetal liver

Epoxide hydrolase activity towards styrene oxide was measured in the microsomal fraction of 20 human fetal livers. The enzymatic activity was 5.60 +/- 0.52 nmol/min/mg (mean +/- SE) which is about 40% of the previously reported value in human adult liver microsomes. No relation between enzymatic activity and fetal age was observed. The kinetics of the enzyme were studied in 6 different livers and found to obey Michaelis-Menten kinetics. The Km ranged between 0.25 and 0.54 mmol/l and Vmax between 7.2 and 16.7 nmol/min/mg microsomal protein. The enzyme was inhibited both by 1,1,1-trichloropropene-2,3-oxide (TCPO; 0.25 mmol/l) and benzo(a)pyrene-4,5-oxide (BPO; 0.2 mmol/l). Those substances inhibited the epoxide hydrolase by 61 and 14%, respectively, at 1 mmol/l styrene oxide. Thus TCPO was considerably more potent as an inhibitor of the fetal liver styrene oxide hydrolase. Lineweaver-Burk plots of the inhibition data revealed that TCPO exerts an uncompetitive mixed type of inhibition.