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Biomedical subjects

Do Young Kim

Publications and source records attributed to Do Young Kim.

At least 19 recordsLinked to original sources
PubMed2006

Clear cell basal cell carcinoma with sialomucin deposition.

Clear cell basal cell carcinoma (BCC) is a variant of BCC with a characteristic clear cell component that may occupy all or part of the tumor islands. Periodic acid-Schiff (PAS) staining for glycogen is variably positive, and mild deposition of sulfated mucin has been noted. However, to our knowledge, clear cell BCC with sialomucin deposition has not been reported. Here we report a case of clear cell BCC showing sialomucin deposition. The clear tumor cells stained with PAS and showed incomplete diastase-resistance. In addition, mucin staining with alcian blue was positive at pH 2.5 but not at pH 0.5.

Aged, 80 and over↗
PubMed2006

Milan criteria are useful predictors for favorable outcomes in hepatocellular carcinoma patients undergoing liver transplantation after transarterial chemoembolization.

AIM: To evaluate whether the Milan criteria are useful in patients with hepatocellular carcinoma (HCC) who received transarterial chemoembolization (TACE) before liver transplantation (LT). METHODS: Thirty-six HCC patients who fulfilled the Milan criteria after having received TACE and subsequently underwent LT were included (TACE + LT group) in the study. As controls, 21 patients who also met the Milan criteria and underwent LT without prior treatment were selected (LT group). Post-LT clinical outcomes, such as HCC recurrence, survival rate, and histologic features of explanted livers, were compared between the two groups. RESULTS: Baseline characteristics were not different between the two groups. Pre-LT maximal tumor diameter in TACE + LT group was similar to that of LT group (2.0 +/- 0.6 cm vs 2.3 +/- 0.9 cm; P = 0.10). Post-LT histologic findings also revealed similar maximal tumor diameter in the two groups (2.4 +/- 1.4 cm vs 2.3 +/- 0.9 cm; P = 0.70). Explanted livers showed similar incidence of unfavorable pathologic features. The morality within 60 d after transplantation was not different between the two groups (8.3% vs 9.5%; P = 0.99). Post-LT 5-year survival rate (57% vs 74%; P = 0.70) and cumulative recurrence rate (8.3% vs 4.8%; P = 0.90) were not significantly different between the two groups. CONCLUSION: The Milan criteria are still a useful selection criteria showing favorable outcomes in HCC patients receiving TACE before LT.

Adult↗
PubMed2006

Inactivation of tyrosine phenol-lyase by Pictet-Spengler reaction and alleviation by T15A mutation on intertwined N-terminal arm.

Citrobacter freundiil-tyrosine phenol-lyase (TPL) was inactivated by a Pictet-Spengler reaction between the cofactor and a substrate, 3,4-dihydroxyphenyl-L-alanine (L-dopa), in proportion to an increase in the reaction temperature. Random mutagenesis of the tpl gene resulted in the generation of a Thr15 to Ala mutant (T15A), which exhibited a two-fold improved activity towards L-DOPA as the substrate. The Thr15 residue was located on the intertwined N-terminal arm of the TPL structure, and comprised an H-bond network in proximity to the hydrophobic core between the catalytic dimers. The maximum activity of the mutant and native enzymes with L-DOPA was detected at 45 and 40 degrees C, respectively, which was 15 degrees C lower than when using L-tyrosine as the substrate. The half-lives at 45 degrees C were about 16.8 and 6.4 min for the mutant and native enzymes, respectively, in 10 mM L-DOPA. On treatment with excess pyridoxal-5'-phosphate (PLP), the L-DOPA-inactivated enzymes recovered over 80% of their original activities, thereby attributing the inactivation to a loss of the cofactor through Pictet-Spengler condensation with L-DOPA. Consistent with the extended half-life, the apparent Michaelis constant of the T15A enzyme for PLP (K(m,PLP)) increased slowly when increasing the temperature, while that of the native enzyme showed a sharp increase at temperatures higher than 50 degrees C, implying that the loss of the cofactor with the Pictet-Spengler reaction was prevented by the tighter binding and smaller release of the cofactor in the mutant enzyme.

Amino Acid Substitution↗
PubMed2006

Synthesis and characterization of the octahydrotriborate complexes Cp*V(B3H8)2 and Cp*Cr(B3H8)2 and the unusual cobaltaborane cluster Cp*2Co2(B6H14).

The new compounds CpV(B(3)H(8))(2), CpCr(B(3)H(8))(2), and Cp(2)Co(2)(B(6)H(14)) have been synthesized by treating the pentamethylcyclopentadienyl complexes [CpVCl(2)](3), [CpCrCl(2)](2), and [CpCoCl](2) with NaB(3)H(8). X-ray crystallography shows that CpV(B(3)H(8))(2) and CpCr(B(3)H(8))(2) have the same ligand sets but different molecular structures: the vanadium compound contains two bidentate B(3)H(8) ligands (i.e., bound to the metal center via two vicinal hydrogen atoms), whereas the chromium compound has one bidentate B(3)H(8) ligand and one B(3)H(8) ligand bound in an unprecedented fashion via two geminal hydrogen atoms. The "gem-bound" B(3)H(8) group itself has an atypical structure consisting of a BH(2)-BH(2)-BH(3) triangle with one additional hydrogen atom bridging the unique BH(2)-BH(2) edge. The B-B distances are nearly identical within experimental error at 1.790(5), 1.792(5), and 1.786(6) Angstrom. The relationship between the electronic and molecular structures of the V and Cr compounds is briefly discussed. The structure of Cp(2)Co(2)(B(6)H(14)) can be viewed in two different ways: as a dicobalt complex in which two CpCo units are each bound to four adjacent boron atoms of an S-shaped B(6)H(14) ligand, or as an eight-vertex hypho cluster compound. In the former case, the B(6)H(14) ligand is best regarded as a dianionic bi-borallyl group H(3)B(mu-H)BH(mu-H)BHBH(mu-H)BH(mu-H)BH(3) in which one hydrogen at each end of the chain is involved in an agostic interaction. From a cluster point of view, the structure of Cp(2)Co(2)(B(6)H(14)) can be generated by removing three adjacent high-connectivity vertices from the eleven-vertex closo polyhedron. The Co-B distances vary from 2.008(5) to 2.183(4) Angstrom, and the B-B distances within in the S-shaped chain range from 1.734(8) to 1.889(6) Angstrom. Finally, a new synthesis of the known molybdenum compound Cp(2)Mo(2)(B(5)H(9)) is described; its structure as established by X-ray crystallography closely resembles that of the previously described (C(5)H(4)Me) analogue.

Journal Article↗
PubMed2006

Association of genetic variations in CCR5 and its ligand, RANTES with clearance of hepatitis B virus in Korea.

Immunogenetic factors may play a role in determining the susceptibility of an individual to viral infection. The aim of current study was to investigate the association of clearance of hepatitis B virus (HBV) with promoter polymorphisms within the CC chemokine receptor 5 (CCR5) and its major ligand, regulated upon activation, normal T cells expressed and secreted (RANTES) genes. Five chemokine system polymorphisms (CCR5 Delta32, CCR5 promoter 59029G/A, 59353C/T, RANTES -403G/A, and -28C/G) were studied in a total of 698 subjects. The carriage of each genetic variant was compared among "spontaneously recovered" group (n = 243), "chronic carrier" group (n = 349), and "unexposed" group (n = 106). CCR5 59029G promoter variant was associated with clearance of HBV infection in an acute phase (OR = 1.71, P = 0.006, dominant model; OR = 2.17, P < 0.001, recessive model) and amelioration of hepatic inflammation (P = 0.003) with the control of HBV replication (P = 0.04) in chronic carriers. Interestingly, CCR5 59029 was linked completely to CCR5 59353, and CCR5 Delta32 homozygosity or heterozygosity was not found in any Korean patient. No association was seen with RANTES polymorphisms at position -403 and -28. The CCR5 59029G/CCR5 59353T polymorphism may play a role in the clearance of HBV infection.

Adult↗
PubMed2006

Electrically stimulated relaxation is not mediated by GABA in cat lower esophageal sphincter muscle.

This study examined the effect of Gamma-Amino butyric acid (GABA) and selective GABA receptor related drugs on the electrically stimulated relaxation in the lower esophageal sphincter muscle (LES) of a cat. Tetrodotoxin (10(-6) M) suppressed the electrically stimulated (0.5-5 Hz) relaxation of the LES. However, guanethidine (10(-6) M) and atropine (10(-6) M) had no effect indicating that the relaxations were neurally mediated via the nonadrenergic and noncholinergic (NANC) pathways. NG-nitro-L-arginine methyl ester (10(-4) M, L-NAME) also inhibited the relaxant response but did not completely abolish the electrically stimulated relaxation with 60 % inhibition, which suggests the involvement of nitric oxide as an inhibitory transmitter. This study examined the role of GABA, an inhibitory neurotransmitter, on neurally mediated LES relaxation. GABA (10(-3)-10(-5) M, non selective receptor agonist), muscimol (10(-3)-10(-5) M, GABA-A agonist), and baclofen (10(-3)-10(-5) M, GABA-B agonist) had no significant effect on the electrically stimulated relaxation. Moreover, bicuculline (10(-5) M, GABA-A antagonist) and phaclofen (10(-5) M, GABA-B antagonist) had no inhibitory effect on the electrically stimulated relaxation. This suggests that GABA and the GABA receptor are not involved in the electrically stimulated NANC relaxation in the cat LES.

Animals↗
PubMed2006

Clinical features and prognosis of hepatocellular carcinoma in young patients from a hepatitis B-endemic area.

BACKGROUND AND AIM: Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. However, the clinical features of young HCC patients have not been fully studied. In the present study, we investigated the prevalence, clinical characteristics and prognosis of young HCC patients. METHODS: A retrospective analysis was performed for HCC patients in our center using Korean cancer registry data. Among 4234 patients enrolled, there were 38 patients younger than 30 years of age (0.9%). We compared clinical characteristics and survival data of these patients (group I) with those of sex-matched, randomly selected HCC patients aged 30-59 years (group II; n = 231) and 60 years or older (group III; n = 147). RESULTS: Group I showed distinct features compared with groups II and III as follows: low frequency of smoking history, high positive rate of hepatitis B s antigen, no association with anti-hepatitis C virus antibody, high frequency of alpha-fetoprotein > or = 400 ng/mL, well-preserved liver function, larger tumor size, more advanced tumor-node-metastasis (TNM) stage and Cancer of the Liver Italian Program (CLIP) score and more frequent application of surgical resection and chemotherapy as initial treatment. The overall survival of group I was worse than that of group II, but similar to that of group III. Multivariate analysis showed that TNM stage and CLIP score, not age itself, were independent predictive factors for survival. CONCLUSIONS: The results suggest that young HCC patients tend to have a poor prognosis owing to advanced tumor stage, despite well-preserved liver function and aggressive treatment. Further studies regarding the role of HCC screening in young people may be useful, especially in hepatitis B virus carriers from high endemic areas.

Adult↗
PubMed2006

[Peginterferon alfa-2a plus ribavirin for initial treatment of chronic hepatitis C in Korea].

BACKGROUND/AIMS: Combination therapy with peginterferon and ribavirin is a standard therapy for western patients with chronic hepatitis C; however, its efficacy remains unclear in East Asian patients. We evaluated the efficacy and safety of administering peginterferon alfa-2a plus ribavirin in native Korean patients with chronic hepatitis C. METHODS: Seventy-five patients with detectable HCV RNA (52.0% male, median age: 50.8 years) were eligible for the study. The patients were treated with peginterferon alfa-2a 180 mcg/week plus ribavirin 800 mg/day for 24 weeks (for genotype non-1, n=46) or 1000-1200 mg/day for 48 weeks (for genotype 1, n=29). The early virologic response (EVR), the end of treatment virologic response (ETVR), the sustained virologic response (SVR), the biochemical response and the adverse event were analyzed. RESULTS: EVR was seen in 86.2% of the patients with genotype 1. The ETVR was 58.6% in the genotype 1 group and 84.8% in the genotype non-1 group (P=0.02). The overall SVR was 70.7%: 55.2% in the genotype 1 group and 80.4% in the non-1 group (P=0.04). The sustained biochemical response was 64.0%. Multivariate analysis showed that the baseline HCV RNA level (Odds ratio: 0.045, 95% CI: 0.011-0.183, P<0.001) and genotype (Odds ratio: 0.247, 95% CI: 0.063-0.969, P=0.045) had an independent effect on the SVR. Neutropenia, anemia, flu-like symptoms and itching were the common adverse events. Aggravated liver function led to discontinuation of therapy for six patients. Dose modification in twenty-nine patients was effective without producing a significant reduction of the SVR. CONCLUSIONS: Our data suggest that the efficacy of peginterferon plus ribavirin therapy in Koreans is comparable to those from studies on Western patients as an initial treatment for chronic hepatitis C patients. The baseline HCV RNA level and the genotype can be significant factors influencing the SVR.

Adult↗
PubMed2006

[Clinical features of liver abscess developed after radiofrequency ablation and transarterial chemoembolization for hepatocellular carcinoma].

BACKGROUND/AIMS: Radiofrequency ablation (RFA) and transarterial chemoembolization (TACE) have been applied for treating hepatocellular carcinoma (HCC), but procedure-related complications can be a serious problem. This study was conducted to evaluate the clinical features of HCC patients who developed liver abscess after RFA and TACE, as compared to those patients without malignancy. METHODS: In our center, from December 1999 to March 2004, 31 cases of liver abscess developed after local treatment of HCC (13/751 after RFA and 18/8417 after TAE), which correspond to 5.1% of the total cases (602) of liver abscess. We evaluated the patients' clinical features, the abscess characteristics, the bacteriology, treatment modality, hospital days and mortality, as compared to those characteristics of 263 abscess patients without malignancy. RESULTS: The time required to diagnose liver abscess was longer in the TACE group (24.8+/-16.5 days) compared to that of the other two groups (12.2+/-9.0 days in the RFA group, 9.6+/-7.5 days in the controls, P=0.001). Gas-forming liver abscess is most frequently found in the RFA groups (76.9%). There were more hospitalized days for the TACE groups than for the RFA group and the controls (34.7+/-19.8 vs. 15.2+/-9.2 vs. 18.6+/-10.9 days, respectively, P<0.001). Two patients (11%) in the TACE group died of sepsis and liver failure. CONCLUSIONS: For the patients with prolonged fever after RFA and especially after TACE for HCC, a diagnosis of liver abscess should be suspected earlier to reduce the morbidity and mortality due to liver abscess per se and also the sepsis-related decompensation of the liver.

Adult↗
PubMed2006

[Natural history of HBeAg negative chronic hepatitis B virus infection: a cohort study].

BACKGROUND/AIMS: The long-term virologic and biochemical changes in patients with HBeAg negative HBV infection, especially in Asia, remain unclear. To address this issue, we conducted a 3 year- retrospective, cohort study. METHODS: A total of 157 patients with HBeAg negative HBV infection who were monitored without treatment were reviewed between January 1999 and March 2004. Those patients were followed up every 3 months with liver function tests and serologic tests. All patients were stratified into 3 groups; inactive carrier (IC), viremic carrier (VC) and chronic hepatitis (CH). Serum HBV DNA was measured by a hybridization assay (sensitivity: 1.4 x 10(5)) genomes/mL, Digene Diagnostics, Silver Spring, USA). RESULTS: The median age of enrolled patients was 42.7 years (M:F=2.3:1). By single time-point observations, the 3 year-cohort prevalence of HBeAg negative CH varied from 12.7 to 35.8% (median 20.7%) HBeAg negative CH was accumulated over time (P=0.002) and transition rates among three groups after 3 years of follow-up are as follows: IC to CH, 6.0%; IC to VC, 4.1%; VC to CH, 23.2%. VC seems to be a disease state in the middle of transition from IC to CH. CONCLUSIONS: We demonstrated the dynamic changing patterns of HBeAg negative CH with time, of which the change from IC or VC to CH was dominant.

Adult↗
PubMed2005

Electrophysiological properties of human hypothalamic hamartomas.

The hypothalamic hamartoma (HH) is a rare developmental malformation often characterized by gelastic seizures, which are usually refractory to medical therapy. The mechanisms of epileptogenesis operative in this subcortical lesion are unknown. In this study, we used standard patch-clamp electrophysiological techniques combined with histochemical approaches to study individual cells from human HH tissue immediately after surgical resection. More than 90% of dissociated HH cells were small (6-9 microm soma) and exhibited immunoreactivity to the neuronal marker NeuN, and to glutamic acid decarboxylase, but not to glial fibrillary acidic protein. Under current-clamp, whole-cell recordings in single dissociated cells or in intact HH slices demonstrated typical neuronal responses to depolarizing and hyperpolarizing current injection. In some cases, HH cells exhibited a "sag-like" membrane potential change during membrane hyperpolarization. Interestingly, most HH cells exhibited robust, spontaneous "pacemaker-like" action potential firing. Under voltage-clamp, dissociated HH cells exhibited functional tetrodotoxin (TTX)-sensitive Na(+) and tetraethylammonium-sensitive K(+) currents. Both GABA and glutamate evoked whole-cell currents, with GABA exhibiting a peak current amplitude 10-fold greater than glutamate. These findings suggest that human HH tissues, associated with gelastic seizures, contained predominantly small GABAergic inhibitory neurons that exhibited intrinsic "pacemaker-like" behavior.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2005

Long-term clinical outcome of large volume paracentesis with intravenous albumin in patients with spontaneous bacterial peritonitis: a randomized prospective study.

BACKGROUND AND AIM: Large volume paracentesis (LVP) with plasma volume expansion has been used for tense or refractory ascites. However, still in question is whether it is safe and effective for the treatment of spontaneous bacterial peritonitis (SBP). We addressed this issue and conducted a study to assess safety and long-term outcome of LVP in cirrhotic patients with SBP. METHODS: Forty-two randomly assigned cirrhotic patients with SBP were classified into two groups; Group 1 included 21 patients who were treated with LVP and intravenous albumin; and Group 2 included 21 patients who were treated with diuretics and intravenous albumin. RESULTS: The overall cumulative survival rate was poor in patients with SBP (42.5% and 22.5% at 6 and 12 months, respectively). At 7 days after treatment, the blood tests were similar between the two groups. In the ascitic fluid, the white blood cell counts decreased significantly and the protein concentrations tended to increase in both groups. In-hospital days, resolution rate of SBP, and in-hospital mortality rate were similar between the two groups. Although complication rates tended to be slightly higher in Group 1, long-term cumulative survivals were similar between Group 1 and Group 2. LVP was effective in removing abdominal discomfort in patients with tense ascites without serious complication. CONCLUSIONS: LVP with intravenous albumin was as effective as diuretics with intravenous albumin for the treatment of SBP with similar mortality. LVP with intravenous albumin might be feasible for the treatment of tense or refractory ascites in cirrhotic patients with SBP.

Albumins↗
PubMed2005

Voltage-gated calcium channels play crucial roles in the glutamate-induced phase shifts of the rat suprachiasmatic circadian clock.

The resetting of the circadian clock based on photic cues delivered by the glutamatergic retinohypothalamic tract is an important process helping mammals to function adaptively to the daily light-dark cycle. To see if the photic resetting relies on voltage-gated Ca(2+) channels (VGCCs), we examined the effects of VGCC blockers on the glutamate-induced phase shifts of circadian firing activity rhythms of suprachiasmatic nucleus (SCN) neurons in hypothalamic slices. First, we found that a cocktail of amiloride, nimodipine and omega-conotoxin MVIIC (T-, L- and NPQ-type VGCC antagonists, respectively) completely blocked both phase delays and advances, which were, respectively, induced by glutamate application in early and late night. Next, we discovered that: (i) amiloride and another T-type VGCC antagonist, mibefradil, completely obstructed the delays without affecting the advances; (ii) nimodipine completely blocked the advances while having less impact on delays; and (iii) omega-conotoxin MVIIC blocked largely, if not entirely, both delays and advances. Subsequent whole-cell recordings revealed that T-type Ca(2+) currents in neurons in the ventrolateral, not dorsomedial, region of the SCN were larger during early than late night, whereas L-type Ca(2+) currents did not differ from early to late night in both regions. These results indicate that VGCCs play important roles in glutamate-induced phase shifts, T-type being more important for phase delays and L-type being so for phase advances. Moreover, the results point to the possibility that a nocturnal modulation of T-type Ca(2+) current in retinorecipient neurons is related to the differential involvement of T-type VGCC in phase delays and advances.

Analysis of Variance↗
PubMed2005

Usefulness of urine strip test in the rapid diagnosis of spontaneous bacterial peritonitis.

PURPOSE: Rapid and accurate diagnosis of spontaneous bacterial peritonitis (SBP) is mandatory for timely treatment in cirrhotic patients. The purpose of this study was to assess the usefulness of two different reagent strips, the UriSCAN and the Multistix10SG, for the rapid bedside diagnosis of SBP. METHODS: A total of 75 paracenteses in 53 cirrhotic patients with ascites were performed. All ascitic fluid was analyzed with the two reagent strips, and compared with the manual cell count with differential and ascitic fluid culture. SBP was defined as an ascitic polymorphonuclear cell count > or =250/mm3. RESULTS: SBP was diagnosed in 18 of the 75 samples. If we considered the positive UriSCAN result of 2 or more, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were all 100%. When we considered the positive UriSCAN result of 3, the sensitivity, specificity, PPV, and NPV were 67%, 100%, 100%, and 89%, respectively. When we considered the positive Multistix10SG result of 3, the sensitivity, specificity, PPV, and NPV were 50%, 100%, 100%, and 87%, respectively. CONCLUSION: Urine reagent strip might be useful for rapid and accurate diagnosis of SBP in cirrhotic patients with ascites.

Ascitic Fluid↗
PubMed2005

[Association between CCR5 promoter polymorphisms and hepatitis B virus infection].

BACKGROUND/AIMS: Immunogenetic factors may play a role in determining the susceptibility of an individual to viral infection. CCR5 promoter polymorphisms are known to be associated with HIV infection. However, there has been no report on the association between CCR5 promoter polymorphism and HBV infection. Therefore, we investigated the relationship between the CCR5 promoter polymorphism and HBV infection. METHODS: A total of 377 patients were classified into two groups according to their HBV infection status: (1) the spontaneous clearance group (SC); HBsAg (-), anti-HBc (+), anti-HBs (+) (2) the chronic HBsAg (+) carrier group (CC); HBsAg (+), anti-HBc (+), anti-HBs (-). CCR5 polymorphisms were detected by employing matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS)- based SNP scoring assay, termed Restriction Fragment Mass Polymorphism (RFMP), which exploits the differences in molecular masses between the common allele and rare allele bases of interest. RESULTS: We found that the genotype frequencies of CCR5 A59029G significantly differed between the SC group (n=138) and CC group (n=239) (P<0.05). The CCR5 59029A allelic genotype was associated with an increased risks of chronic infection rather than spontaneous clearance (P=0.002), and the presence of the CCR5 59029G allele was significantly associated with the spontaneous clearance of HBV (P=0.001). Strong linkage disequilibrium between the CCR5-59029 and the CCR5-59353 polymorphic variants was identified. None of the 377 subjects had the CCR5-32 bp deletion mutation. CONCLUSIONS: The CCR5 promoter polymorphisms at position 59029 might play a role in the clearance of HBV infection. This primary experimental evidence needs further studies to clarify the clinical usefulness of CCR5 promoter polymorphisms as a target for the screening or treatment of HBV infection.

Adult↗
PubMed2005

Molecular characterization of extracellular medium-chain-length poly(3-hydroxyalkanoate) depolymerase genes from Pseudomonas alcaligenes strains.

A bacterial strain M4-7 capable of degrading various polyesters, such as poly(epsilon-caprolactone), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxyoctanoate), and poly(3-hydroxy-5-phenylvalerate), was isolated from a marine environment and identified as Pseudomonas alcaligenes. The relative molecular mass of a purified extracellular medium-chain-length poly(3-hydroxyalkanoate) (MCL-PHA) depolymerase (PhaZ(PalM4-7)) from P. alcaligenes M4-7 was 28.0 kDa, as determined by SDS-PAGE. The PhaZ(PalM4-7) was most active in 50 mM glycine-NaOH buffer (pH 9.0) at 35 degrees C. It was insensitive to dithiothreitol, sodium azide, and iodoacetamide, but susceptible to p-hydroxymercuribenzoic acid, N-bromosuccinimide, acetic anhydride, EDTA, diisopropyl fluorophosphate, phenylmethylsulfonyl fluoride, Tween 80, and Triton X-100. In this study, the genes encoding MCL-PHA depolymerase were cloned, sequenced, and characterized from a soil bacterium, P. alcaligenes LB19 (Kim et al., 2002, Biomacromolecules 3, 291-296) as well as P. alcaligenes M4-7. The structural gene (phaZ(PalLB19)) of MCL-PHA depolymerase of P. alcaligenes LB19 consisted of an 837 bp open reading frame (ORF) encoding a protein of 278 amino acids with a deduced M((r)) of 30,188 Da. However, the MCL-PHA depolymerase gene (phaZ(PalM4-7)) of P. alcaligenes M4-7 was composed of an 834 bp ORF encoding a protein of 277 amino acids with a deduced Mr of 30,323 Da. Amino acid sequence analyses showed that, in the two different polypeptides, a substrate-binding domain and a catalytic domain are located in the N-terminus and in the C-terminus, respectively. The PhaZ(PalLB19) and the PhaZ(PalM4-7) commonly share the lipase box, GISSG, in their catalytic domains, and utilize 111Asn and 110Ser residues, respectively, as oxyanions that play an important role in transition-state stabilization of hydrolytic reactions.

Amino Acid Sequence↗