RESUMO
This study investigated the efficacy of the prophylactic human papillomavirus (HPV) vaccine, which was initiated between 2009 and 2013 in Japan. The study involved 1529 eligible women aged 16-39 years who visited 11 outpatient clinics in Japan for various reasons. These patients underwent HPV genotype analysis and a Pap test of cervical cell samples. A total of 299 women (19.6%) had received the prophylactic HPV vaccine (bivalent:quadrivalent vaccine ratio = 2:1). Of the 5062 participants in the Japanese Human Papillomavirus Disease Education and Research Survey (J-HERS 2011), which was conducted in the pre-vaccination era, 3236 eligible participants were included as controls. In this study (J-HERS 2021), the highest rate of HPV vaccination (53%) was observed in patients aged 22-27 years. Vaccinated individuals exhibited a 49% rate of protection against low-grade intraepithelial lesions (LSILs) and atypical squamous cells, not excluding high-grade squamous intraepithelial lesions (ASCH) or worse (LSIL/ASCH+), and a 100% rate of protection against high-grade squamous intraepithelial lesions (HSILs) or worse (HSIL+). Significant reductions in HPV16 (95%) and HPV18 (100%) infections were noted, but no differences were observed in HPV6 and HPV11 infections. The prevalences of HPV51 and HPV59 increased with vaccination, although these changes were not confirmed in the comparative study with J-HERS 2011. Comparing the prevaccination (J-HERS 2011) and postvaccination (J-HERS 2021) periods, 43%, 51%, 88%, and 62% reductions in HPV16, HPV18, HPV16/18, and HPV31/58 infection rates were observed, respectively. Similarly, 62% and 71% reductions in LSIL/ASCH+ and HSIL+ rates were noted, respectively. There were 88% and 87% reductions in LSIL/ASCH+ and HSIL+ rates in 16-21- and 28-33-year-old patients, respectively. Bivalent or quadrivalent vaccines provided 100% protection against high-grade squamous cell lesions (suggestive of CIN2 or CIN3) in young women aged <39 years at 9-12 years after initiation of Japan's first nationwide HPV vaccination program. Cross-protection against HPV31 and HPV58 is likely to occur, although some HPV-type replacements are inconsistent across vaccination regimens. This demonstrates the effectiveness of the HPV vaccine. However, continuous monitoring of cervical cancer and precancer is necessary in younger generations (born 1997-2007), who were rarely vaccinated due to the prolonged suspension of the vaccine recommendations in Japan.
Assuntos
Infecções por Papillomavirus , Vacinas contra Papillomavirus , Lesões Intraepiteliais Escamosas , Displasia do Colo do Útero , Neoplasias do Colo do Útero , Humanos , Feminino , Infecções por Papillomavirus/epidemiologia , Infecções por Papillomavirus/prevenção & controle , Japão/epidemiologia , Papillomavirus Humano 16 , Papillomavirus Humano 18 , Neoplasias do Colo do Útero/epidemiologia , Neoplasias do Colo do Útero/prevenção & controle , Neoplasias do Colo do Útero/patologia , Papillomaviridae/genética , Papillomavirus Humano 31 , Vacinas CombinadasRESUMO
Survivin is overexpressed in various cancers and is correlated with treatment resistance and prognosis. MicroRNAs (miRNAs) directly regulate several target genes and are potential therapeutic agents for various cancers. The present study evaluated multiple gene targets of miR218, including survivin, in osteosarcoma and compared the antitumor effects of miR218 with those of YM155, an antisurvivin agent. It assessed the expression levels of miR218 and survivin in osteosarcoma and osteoblast cell lines, as well as the proliferative, migratory and invasive capacities of cells following treatment with miR218 or YM155. The form of cell death was assessed using fluorescenceactivated cell sorting analysis to examine the expression of invasion abilityrelated genes. Osteosarcoma cell lines were subcutaneously injected into immunodeficient mice; the mice were then treated with miR218 or YM155 to assess the antitumor effects of these agents. The results showed that miR218 was downregulated, whereas survivin was overexpressed in the osteosarcoma cell line compared with normal osteoblast cells. The expression of survivin was suppressed upon overexpression of miR218 (miR218 group) or administration of YM155 (YM155 group), leading to apoptosis and inhibition of osteosarcoma cell proliferation. Invasion and migration abilities were inhibited in the miR218 group, but not in the YM155 group. In the animal model, both the miR218 and YM155 groups showed a reduced tumor volume and decreased survivin expression. In osteosarcoma, miR218 showed a wider range of therapeutic efficacy compared with YM155, suggesting that miR218 should be evaluated as a treatment target.
Assuntos
Neoplasias Ósseas , MicroRNAs , Oncogenes , Osteossarcoma , Animais , Neoplasias Ósseas/tratamento farmacológico , Neoplasias Ósseas/genética , Linhagem Celular Tumoral , Camundongos , MicroRNAs/genética , MicroRNAs/uso terapêutico , Osteossarcoma/tratamento farmacológico , Osteossarcoma/genéticaRESUMO
Microphysiological systems (MPS) or organs-on-chips (OoC) can emulate the physiological functions of organs in vitro and are effective tools for determining human drug responses in preclinical studies. However, the analysis of MPS has relied heavily on optical tools, resulting in difficulties in real-time and high spatial resolution imaging of the target cell functions. In this study, the role of scanning probe microscopy (SPM) as an analytical tool for MPS is evaluated. An access hole is made in a typical MPS system with stacked microchannels to insert SPM probes into the system. For the first study, a simple vascular model composed of only endothelial cells is prepared for SPM analysis. Changes in permeability and local chemical flux are quantitatively evaluated during the construction of the vascular system. The morphological changes in the endothelial cells after flow stimulation are imaged at the single-cell level for topographical analysis. Finally, the possibility of adapting the permeability and topographical analysis using SPM for the intestinal vascular system is further evaluated. It is believed that this study will pave the way for an in situ permeability assay and structural analysis of MPS using SPM.
Assuntos
Células Endoteliais , Dispositivos Lab-On-A-Chip , Humanos , Microscopia de Varredura por Sonda , PermeabilidadeRESUMO
The purpose of the protocol is to indirectly evaluate the direction of the finger force during manipulation of a handheld object based on the biomechanical relationships in which deviated force direction causes center of pressure (COP) replacement. To evaluate this, a thin, flexible, and high spatial resolution pressure sensor sheet is used. The system allows measurement of the COP trajectory in addition to the force amplitude and its temporal regulation. A series of experiments found that increased trajectory length reflected a sensorimotor deficit in stroke patients, and that decreased COP trajectory reflects a compensatory strategy to avoid an object slipping from the hand grip in the elderly. Moreover, the COP trajectory could also be decreased by dual task interference. This article describes the experimental procedure and discusses how finger COP contributes to an understanding of the physiology and pathophysiology of grasping.
Assuntos
Força da Mão/fisiologia , Fenômenos Mecânicos , Adulto , Idoso , Fenômenos Biomecânicos , Feminino , Dedos/fisiologia , Dedos/fisiopatologia , Humanos , Masculino , Acidente Vascular Cerebral/fisiopatologiaRESUMO
BACKGROUND/AIM: miRNA-1(miR-1) is down-regulated in various cancer cells including osteosarcoma cells. This study was conducted to analyze the function of miR-1 in osteosarcoma cells. MATERIALS AND METHODS: miR-1 expression in osteosarcoma cells was evaluated by qRT-PCR. Cell proliferation was evaluated after transfecting miR-1 by WST8 assay and FACS analysis, both in vitro and in vivo. RESULTS: Overexpression of miR-1 suppressed cell proliferation and induced cell-cycle arrest in the G0-G1 phase by increasing p21 levels via a p53-independent pathway. Overexpression of miR-1 down-regulated PAX3, a potential p21-regulating gene. Moreover, knockdown of PAX3 suppressed cell proliferation by increasing p21 levels, and induced arrest at the G0/G1 phase. Administration of miR-1 showed an in vivo antitumor effect. CONCLUSION: Overexpression of miR-1 suppressed cell proliferation and induced arrest in the G0/G1 phase by increasing p21 levels via a p53-independent pathway through PAX3 suppression. These results indicate that miR-1 could be a therapeutic target for osteosarcoma.
Assuntos
Neoplasias Ósseas/genética , Inibidor de Quinase Dependente de Ciclina p21/genética , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Osteossarcoma/genética , Fator de Transcrição PAX3/genética , Interferência de RNA , Apoptose/genética , Neoplasias Ósseas/metabolismo , Neoplasias Ósseas/patologia , Ciclo Celular/genética , Linhagem Celular Tumoral , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Humanos , Osteossarcoma/metabolismo , Osteossarcoma/patologia , Fator de Transcrição PAX3/metabolismo , Transdução de Sinais , Proteína Supressora de Tumor p53/metabolismoRESUMO
Luteinized unruptured follicle (LUF) syndrome is one of the intractable ovulation disorders that are commonly observed during cycles of treatment with ovulation inducers, for which no effective therapy other than assisted reproductive technology is available. Here, we investigated whether granulocyte colony-stimulating factor (G-CSF) could prevent the onset of LUF syndrome. We analyzed the effects of G-CSF in 68 infertile women with LUF syndrome who received ovulation induction (clomiphene + human chorionic gonadotropin [hCG] therapy or follicle-stimulating hormone + hCG therapy). G-CSF (lenograstim, 100 µg) was administered subcutaneously. Onsets of LUF syndrome were compared between the cycle during which G-CSF was given in combination with the ovulation inducer (ie, the G-CSF treatment cycle) and the subsequent cycle during which only the ovulation inducer was given (ie, the G-CSF nontreatment control cycle). The results showed that LUF syndrome recurred in only 3 cycles during the G-CSF treatment cycle (4.4% [3/68 cycles]), whereas LUF syndrome recurred in 13 cycles during the subsequent G-CSF nontreatment control cycle (19.1% [13/68 cycles]). The additional use of G-CSF significantly prevented the onset of LUF syndrome during ovulation induction (P = 0.013, McNemar test). No serious adverse reactions because of the administration of G-CSF were observed. In conclusion, our findings indicate that G-CSF may become a useful therapy for LUF syndrome.
Assuntos
Fator Estimulador de Colônias de Granulócitos/farmacologia , Infertilidade Feminina/fisiopatologia , Ovulação/efeitos dos fármacos , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Hormônio Luteinizante/farmacologia , Indução da Ovulação , Gravidez , SíndromeRESUMO
OBJECTIVE: The purpose of this retrospective study is to determine the fetal lung-to-liver signal intensity ratio (LLSIR) on T2-weighted images for the prediction of neonatal respiratory outcome. METHODS: One hundred ten fetuses who underwent magnetic resonance imaging (MRI) examination for various indications after 22 weeks of gestation participated in this study. LLSIR was measured as the ratio of signal intensities of the fetal lung and liver on T2-weighted images at MRI. We examined the changes of the ratio with advancing gestation and the relations between LLSIR and the presence of the severe respiratory disorder (SRD) after birth. The best cut-off value of the LLSIR to predict respiratory outcome after birth was calculated using receiver operating characteristic (ROC) curve analysis. RESULTS: Lung-to-liver signal intensity ratio correlated significantly with advancing gestational age (R = 0.35, p < 0.001). The non-SRD group had higher LLSIR compared with the SRD group (2.15 ± 0.30 vs. 1.53 ± 0.40, p < 0.001). ROC curve analysis showed that fetuses with an LLSIR < 2.00 were more likely to develop SRD [sensitivity: 100%, 95% confidence interval (CI): 52-100%; specificity: 73%, 95% CI 54-88%]. CONCLUSION: The fetal LLSIR on T2-weighted images is an accurate marker to diagnose the fetal lung maturity.
Assuntos
Doenças Fetais/diagnóstico , Imageamento por Ressonância Magnética , Diagnóstico Pré-Natal , Testes de Função Respiratória , Insuficiência Respiratória/diagnóstico , Feminino , Humanos , Fígado , Pulmão , Gravidez , Estudos RetrospectivosRESUMO
We describe a simple and easy protocol to introduce random mutations into plasmid DNA: error-prone rolling circle amplification. A template plasmid is amplified via rolling circle amplification with decreased fidelity in the presence of MnCl2 and is used to transform a host strain resulting in a mutant library with several random point mutations per kilobase through the entire plasmid. The primary advantage of this method is its simplicity. This protocol does not require the design of specific primers or thermal cycling. The reaction mixture can be used for direct transformation of a host strain. This method allows rapid preparation of randomly mutated plasmid libraries, enabling wider application of random mutagenesis.
Assuntos
Mutagênese/genética , Técnicas de Amplificação de Ácido Nucleico/métodos , Evolução Molecular DirecionadaRESUMO
Although proteins can be artificially improved by random insertion and deletion mutagenesis methods, these procedures are technically difficult. Here we describe a simple method called random insertional-deletional strand exchange mutagenesis (RAISE). This method is based on gene shuffling and can be used to introduce a wide variety of insertions, deletions, and substitutions. RAISE involves three steps: DNA fragmentation, attachment of a random short sequence, and reconstruction. This yields unique mutants and can be a powerful technique for protein engineering.
Assuntos
Mutagênese Insercional/métodos , Deleção de Sequência/genéticaRESUMO
Some serine hydrolases also catalyze a promiscuous reaction--reversible perhydrolysis of carboxylic acids to make peroxycarboxylic acids. Five X-ray crystal structures of these carboxylic acid perhydrolases show a proline in the oxyanion loop. Here, we test whether this proline is essential for high perhydrolysis activity using Pseudomonas fluorescens esterase (PFE). The L29P variant of this esterase catalyzes perhydrolysis 43-fold faster (k(cat) comparison) than the wild type. Surprisingly, saturation mutagenesis at the 29 position of PFE identified six other amino acid substitutions that increase perhydrolysis of acetic acid at least fourfold over the wild type. The best variant, L29I PFE, catalyzed perhydrolysis 83-times faster (k(cat) comparison) than wild-type PFE and twice as fast as L29P PFE. Despite the different amino acid in the oxyanion loop, L29I PFE shows a similar selectivity for hydrogen peroxide over water as L29P PFE (ß(0)=170 vs. 160 M(-1)), and a similar fast formation of acetyl-enzyme (140 vs. 62 U mg(-1)). X-ray crystal structures of L29I PFE with and without bound acetate show an unusual mixture of two different oxyanion loop conformations. The type II ß-turn conformation resembles the wild-type structure and is unlikely to increase perhydrolysis, but the type I ß-turn conformation creates a binding site for a second acetate. Modeling suggests that a previously proposed mechanism for L29P PFE can be extended to include L29I PFE, so that an acetate accepts a hydrogen bond to promote faster formation of the acetyl-enzyme.
Assuntos
Ácidos Carboxílicos/química , Hidrolases de Éster Carboxílico/química , Esterases/química , Prolina/química , Pseudomonas fluorescens/enzimologia , Sítios de Ligação , Hidrolases de Éster Carboxílico/metabolismo , Catálise , Cristalografia por Raios X , Esterases/metabolismo , Ligação de Hidrogênio , Cinética , Modelos Moleculares , Estrutura Molecular , Engenharia de Proteínas , Água/químicaRESUMO
This study examined the relationship between intimate partner violence (IPV) and unintended pregnancy using data from women reporting IPV in the 2007 Bangladesh Demographic Health Survey. The analysis included 4,695 married women, aged 15 to 40 years, who had at least one birth in the last 5 years. Bivariate and multiple logistic regression analyses were performed to assess the relationship between IPV and pregnancy. About one third (30.4%) of women were abused physically and/or sexually and about one third (30.9%) of their births in the last 5 years were unintended. Compared with women who suffered no IPV, women who were abused sexually had a 1.64-fold increased risk of unintended pregnancy, which is higher than those who suffered physical abuse only (odds ratio: 1.35). The prevalence of unintended pregnancy among those who experienced severe physical violence was 1.60 times higher than those who reported no abuse. The findings indicate a significant relationship between IPV and unintended pregnancy among Bangladeshi women.
Assuntos
Mulheres Maltratadas/estatística & dados numéricos , Vítimas de Crime/estatística & dados numéricos , Gravidez não Desejada , Parceiros Sexuais , Maus-Tratos Conjugais/estatística & dados numéricos , Adolescente , Adulto , Bangladesh/epidemiologia , Saúde da Família , Feminino , Humanos , Modelos Logísticos , Masculino , Mães , Gravidez , Prevalência , Adulto JovemRESUMO
The alpha/beta hydrolase superfamily contains mainly esterases, which catalyze hydrolysis, but also includes hydroxynitrile lyases, which catalyze addition of cyanide to aldehydes, a carbon-carbon bond formation. Here, we convert a plant esterase, SABP2, into a hydroxynitrile lyase using just two amino acid substitutions. Variant SABP2-G12T-M239K lost the ability to catalyze ester hydrolysis (<0.9 mU/mg) and gained the ability to catalyze the release of cyanide from mandelonitrile (20 mU/mg, k(cat)/K(M) = 70 min(-1)M(-1)). This variant also catalyzed the reverse reaction, formation of mandelonitrile with low enantioselectivity: 20% ee (S), E = 1.5. The specificity constant for the lysis of mandelontrile is 13,000-fold faster than the uncatalyzed reaction and only 1300-fold less efficient (k(cat/)K(M)) than hydroxynitrile lyase from rubber tree.
Assuntos
Aldeído Liases/genética , Aldeído Liases/metabolismo , Substituição de Aminoácidos , Esterases/genética , Esterases/metabolismo , Aldeído Liases/química , Biocatálise , Domínio Catalítico , Esterases/química , Hevea/enzimologia , Modelos Moleculares , Alinhamento de Sequência , Estereoisomerismo , Especificidade por SubstratoRESUMO
Entering the fold: A common structural motif in hydrolytic enzymes is the alpha,beta-hydrolase fold. The interconversion of one enzyme into another by introduction of mechanistically important residues is not enough; only substitution of a loop allows epoxide hydrolase activity in the esterase scaffold to be formed (see picture; structure comparison of epoxide hydrolases (green) with the esterase (orange)). The result is an enantioselective chimeric enzyme.
Assuntos
Epóxido Hidrolases/química , Esterases/química , Sequência de Aminoácidos , Substituição de Aminoácidos , Catálise , Epóxido Hidrolases/genética , Esterases/genética , Evolução Molecular , Hidrólise , Dados de Sequência Molecular , Mutação , Conformação Proteica , Dobramento de Proteína , Estirenos/química , Especificidade por SubstratoRESUMO
Although proteins may be artificially improved by random insertion and deletion mutagenesis methods, these procedures are technically difficult, and the mutations introduced are no more variable than those introduced by the introduction of random point mutations. We describe here a three-step method called RAISE, which is based on gene shuffling and can introduce a wide variety of insertions, deletions and substitutions. To test the efficacy of this method, we used it to mutate TEM beta-lactamase to generate improved antibiotic resistance. Some unique insertion or deletion mutations were observed in the improved mutants, some of which caused higher activities than point mutations. Our findings indicate that the RAISE method can yield unique mutants and may be a powerful technique of protein engineering.
Assuntos
Mutagênese Insercional/métodos , Mutagênese , Engenharia de Proteínas/métodos , Deleção de Sequência , Substituição de Aminoácidos , Antibacterianos/metabolismo , Ceftazidima/metabolismo , Embaralhamento de DNA , Farmacorresistência Bacteriana , Mutação Puntual , beta-Lactamases/genética , beta-Lactamases/metabolismoRESUMO
BACKGROUND: A method for intravital microscopy of the rabbit ovary was developed to enable observations of real-time changes during ovulation in vivo. The aim was to correlate these events to biochemical events at specific stages of ovulation. METHODS: Virgin, female rabbits were primed with equine chorionic gonadotrophin (CG) (30-100 IU) then HCG (100 IU) 2 days later to induce ovulation. During anaesthesia, the right ovary was surgically exteriorized and submerged in an organ chamber with a microscopy lens positioned close to the ovary. Continuous video recordings were performed. RESULTS: Initial equine CG priming experiments revealed the highest ovulation rate, without premature luteinization, after 30 IU equine CG. This priming protocol subsequently demonstrated follicular ruptures 11.5-14 h after HCG. Numbers of ovulations from the exteriorized and contralateral non-exteriorized ovary were similar. The sequence of typical features of ovulation was: shutdown of microcirculation in the follicular apex, formation of petechiae in the follicular wall and a cone-shaped structure over the future rupture site, marked bleeding in connection with follicular rupture and a fairly steady extrusion velocity of granulosa cells and the oocyte. CONCLUSION: This method captured a sequence of structural changes during ovulation. It could be combined with blood and follicular fluid sampling for biochemical analysis and could be used in studies on biochemical reactions in relation to specific changes in the follicular structure during ovulation.
Assuntos
Ovário/citologia , Ovulação/fisiologia , Animais , Gonadotropina Coriônica/farmacologia , Feminino , Células da Granulosa/citologia , Células da Granulosa/efeitos dos fármacos , Células da Granulosa/fisiologia , Cavalos , Técnicas In Vitro , Folículo Ovariano/citologia , Folículo Ovariano/efeitos dos fármacos , Folículo Ovariano/fisiologia , Ovário/efeitos dos fármacos , Ovário/fisiologia , Ovulação/efeitos dos fármacos , CoelhosRESUMO
A simple protocol to introduce random mutations, named error-prone rolling circle amplification (RCA), is described. A template plasmid is amplified by RCA in the presence of MnCl2 and used for transformation of a host strain to give a mutant library with three to four random point mutations per kilobase throughout the entire plasmid. The prime advantage of this method is its simplicity. This protocol requires neither the design of specific primers nor the exploration of thermal cycling conditions. It takes just 10 min to prepare the reaction mixture, followed by overnight incubation and transformation of a host strain. This method permits rapid preparation of randomly mutated plasmid libraries, and will enable the wider adoption of random mutagenesis.
Assuntos
Mutagênese , Técnicas de Amplificação de Ácido Nucleico/métodos , Plasmídeos , Cloretos , Biblioteca Gênica , Técnicas de Transferência de Genes , Compostos de Manganês , MutaçãoRESUMO
A lipase from Pseudomonas aeruginosa was subjected to directed molecular evolution for increased amide-hydrolyzing (amidase) activity. A single round of random mutagenesis followed by screening for hydrolytic activity for oleoyl 2-naphthylamide as compared with that for oleoyl 2-naphthyl ester identified five mutants with 1.7-2.0-fold increased relative amidase activities. Three mutational sites (F207S, A213D and F265L) were found to affect the amidase/esterase activity ratios. The combination of these mutations further improved the amidase activity. Active-site titration using a fluorescent phosphonic acid ester allowed the molecular activities for the amide and the ester to be determined for each mutant without purification of the lipase. A double mutant F207S/A213D gave the highest molecular activity of 1.1 min(-1) for the amide, corresponding to a 2-fold increase compared with that of the wild-type lipase. A structural model of the lipase indicated that the mutations occurred at the sites near the surface and remote from the catalytic triad, but close to the calcium binding site. This study is a first step towards understanding why lipases do not hydrolyze amides despite the similarities to serine proteases in the active site structure and the reaction mechanism and towards the preparation of a general acyl transfer catalyst for the biotransformation of amides.
Assuntos
Amidas/metabolismo , Evolução Molecular Direcionada , Lipase/metabolismo , Pseudomonas aeruginosa/enzimologia , Sequência de Bases , Primers do DNA , Hidrólise , Lipase/genética , Dados de Sequência Molecular , Mutagênese , PlasmídeosRESUMO
In vitro random mutagenesis is a powerful tool for altering properties of enzymes. We describe here a novel random mutagenesis method using rolling circle amplification, named error-prone RCA. This method consists of only one DNA amplification step followed by transformation of the host strain, without treatment with any restriction enzymes or DNA ligases, and results in a randomly mutated plasmid library with 3-4 mutations per kilobase. Specific primers or special equipment, such as a thermal-cycler, are not required. This method permits rapid preparation of randomly mutated plasmid libraries, enabling random mutagenesis to become a more commonly used technique.
Assuntos
Evolução Molecular Direcionada/métodos , Mutagênese , Ceftazidima/farmacologia , DNA Circular/biossíntese , Resistência a Medicamentos , Biblioteca Gênica , Mutação , Especificidade por Substrato , Transformação Genética , beta-Lactamases/metabolismoRESUMO
The fluorescent organophosphorus esters, diethyl 4-methylumbelliferyl phosphate (1), ethyl hexyl 4-methylumbelliferyl phosphate (2) and ethyl 4-methylumbelliferyl heptylphosphonate (3) have been synthesized and evaluated as a sensitive active-site titrant of lipase. The phosphorus esters 1, 2 and 3 inactivated the lipase from Pseudomonas aeruginosa (LPL-312) with a second-order rate constant for enzyme inactivation (k(on)) of 1.8, 32 and 5600 s(-1) M(-1), respectively. The long-chain phosphonate 3 turned out to be the most potent inactivator of the lipase to release a stoichiometric amount of highly fluorescent 4-methylumbelliferone (4MU) as a leaving group. By using the phosphate 3 as an active-site titrant, the low concentration (4.5 nM) of the active lipase was titrated successfully. The highly sensitive active-site titration with 3 enabled the direct determination of the concentration of the active lipase expressed in a microscale culture medium. Although the expression level differed significantly from one culture to another, the titrated concentration of the active lipase was proportional to the apparent activity for all the independent cultures. The molecular activity calculated for the expressed lipase was found to be the same as that of the purified lipase. The present active-site titration method is widely applicable to the biocatalytic engineering of lipases such as directed evolution, site-directed mutagenesis, chemical modification and immobilization.