Significance of the prognostic nutritional index in patients with esophageal squamous cell carcinoma

Background

The prognostic nutritional index (PNI) is related to the prognosis in many cancers; however, its role in esophageal cancer is still controversial. Further, controversy exists concerning the optimal cut-off points for PNI to predict survival. The aim of this study was to determine the prognostic value of PNI and propose the optimal cut-off points for PNI in predicting cancer-specific survival (CSS) in esophageal squamous cell carcinoma (ESCC).

Methods

This retrospective study included 375 patients who underwent esophagectomy for ESCC. The PNI was calculated as 10 × serum albumin (g/dL) + 0.005 × total lymphocyte count (per mm³). With the help of the fit line on the scatter plot, we classified the patients into three categories according to the PNI, ie, >52, 42–52, and <42.

Results

Our study showed that PNI was associated with tumor length (P=0.007), T grade (P=0.001), and N staging (P<0.001). The 5-year CSS in patients with PNI <42, 42–52, and >52 were 11.0%, 39.1%, and 55.2%, respectively (P<0.001). Multivariate analysis showed that PNI was a significant predictor of CSS (42–52 versus >52, P=0.011; <42 versus PNI >52, P<0.001).

Conclusion

PNI is a predictive factor for long-term survival in ESCC. The survival rate of ESCC can be discriminated between three groups, ie, PNI <42, 42–52, and >52.

Significance of preoperative C-reactive protein as a parameter in patients with small cell carcinoma of the esophagus

Background

C-reactive protein (CRP) is inversely related to prognosis in many cancers, however, no studies regarding the predictive value of CRP in small cell carcinoma of the esophagus (SCCE) are available. The aim of this study was to determine the prognostic value of preoperative CRP in patients with SCCE.

Methods

From January 2001 to December 2010, a retrospective analysis of 43 consecutive patients with SCCE was conducted. Univariate and multivariate analyses were performed to evaluate the prognostic parameters.

Results

In our study, elevated CRP levels (>10 mg/L) were found in 16 patients (37.2%). CRP levels were significantly higher in patients with deeply invasive tumors (P = 0.018) and those associated with nodal metastasis (P = 0.018). Patients with CRP ≤10 mg/L had a significantly better overall survival than patients with CRP >10 mg/L (25.9% vs 6.3%, P = 0.004). Multivariate analyses showed that CRP was a significant predictor for overall survival. CRP >10 mg/L had a hazard ratio of 2.756 (95% confidence interval: 1.115–6.813, P = 0.028) for overall survival.

Conclusion

Preoperative CRP is an independent predictive factor for long-term survival in patients with SCCE.

Prognostic significance of solitary lymph node metastasis in patients with squamous cell carcinoma of middle thoracic esophagus

Background

The aim of this study is to compare clinical outcomes between patients with solitary lymph node metastasis and node-negative (N0) patients in squamous cell carcinoma of the middle thoracic esophagus.

Methods

A series of 135 patients with squamous cell carcinoma of the middle thoracic esophagus were retrospectively investigated. There were 33 patients with solitary lymph node metastasis and 102 N0 patients. Skip metastasis in 33 patients with solitary lymph node metastasis was defined according to three criteria: Japanese Society for Esophageal Disease (JSED), American Joint Commission on Cancer (AJCC), and the anatomical compartment.

Results

In 33 patients with solitary lymph node metastasis, skip metastasis was shown in 13, 23, and 8 patients according JSED, AJCC and anatomical compartment respectively. The 5-year survival rates for N0 patients and patients with solitary lymph node metastasis were 58% and 32% respectively (P =0.008). Multivariate analysis revealed that skip metastasis was not an independent prognostic factor.

Conclusions

For patients with middle thoracic esophageal squamous cell carcinoma, solitary lymph node metastasis has a negative impact on survival compared with N0 disease; skip metastasis, however, is comparable to N0 diseases in predicting prognosis.

Dual delivery for stem cell differentiation using dexamethasone and bFGF in/on polymeric microspheres as a cell carrier for nucleus pulposus regeneration

This study aimed to investigate the feasibility of the nanostructured 3D poly(lactide-co-glycolide) (PLGA) constructs, which are loaded with dexamethasone (DEX) and growth factor embedded heparin/poly(L-lysine) nanoparticles via a layer-by-layer system, to serve as an effective scaffold for nucleus pulposus (NP) tissue engineering. Our results demonstrated that the microsphere constructs were capable of simultaneously releasing basic fibroblast growth factor and DEX with approximately zero order kinetics. The dual bead microspheres showed no cytotoxicity, and promoted the proliferation of the rat mesenchymal stem cells (rMSCs) by lactate dehydrogenase assay and CCK-8 assay. After 4 weeks of cultivation in vitro, the rMSCs-scaffold hybrids contained significantly higher levels of sulfated GAG/DNA and collagen type II than the control samples. Moreover, quantitative real time PCR analysis revealed that the expression of disc-matrix proteins including collagen type II, aggrecan, and versican in the rMSCs-scaffold hybrids was significantly higher than that in the control group, whereas the expression of osteogenic differentiation marker (collagen type I) was decreased. Taken together, these data indicate that Dex/bFGF PLGA microspheres could be used as a scaffold to improve the rMSCs growth and differentiating into NP like cells, and reduce the inflammatory response for IVD tissue engineering.

Ivor Lewis subtotal esophagectomy with two-field lymphadenectomy for squamous cell carcinoma of the lower thoracic esophagus

AIM: To evaluate the clinical outcome of Ivor Lewis subtotal esophagectomy with two-field lymphadenectomy for patients with squamous cell carcinoma of the lower thoracic esophagus.

METHODS: From January 1998 to December 2001, 73 patients with lower thoracic esophageal carcinoma underwent Ivor-Lewis subtotal esophagectomy with two-field lymphadenectomy. Clinicopathological information, postoperative complications, mortality and long term survival of all these patients were analyzed retrospectively.

RESULTS: The operative morbidity and mortality was 15.1% and the mortality was 2.7%. Lymph node metastases were found in 52 patients (71.2%). Nodal metastases to the upper, middle, lower mediastini and upper abdomen were found in 13 (17.8%), 15 (20.5%), 30 (41.1%), and 25 (34.2%) patients, respectively. Postoperative staging was as follows: stageI in 5 patients, stage II in 34 patients, stage III in 32 patients, and stage IV in 2 patients, respectively. The overall 5-year survival rate was 23.3%. For N0 and N1 patients, the 5-year survival rate was 38.1% and 17.3%, respectively (χ² = 22.65, P < 0.01). The 5-year survival rate for patients in stages IIa, IIb and III was 31.2%, 27.8% and 12.5%, respectively (χ² = 29.18, P < 0.01).

CONCLUSION: Ivor Lewis subtotal esophagectomy with two-field (total mediastinum) lymphadenectomy is a safe and appropriate operation for squamous cell carcinoma of the lower thoracic esophagus.

[Sleeve resection for lung cancer: a report of 82 cases]

BACKGROUND & OBJECTIVE

Bronchial sleeve resection and/or pulmovascular sleeve resection can maximize preservation of normal lung tissues after tumor resection, which provides a resection mode for lung cancer surgery. This study was to investigate the technique, operative results and survival of lung cancer patients after sleeve resection.

METHODS

Eighty-two central lung cancer patients underwent sleeve resection in Zhejiang Cancer Hospital from Jun. 2001 to Dec. 2006. Among them, 23 underwent concomitant pulmovascular sleeve resection, 2 underwent pulmovascular sleeve resection alone. All patients received systematic lymph node dissection. The results of lymph node dissection and the occurrence of postoperative complications were studied. The survival of patients was analyzed by Kaplan-Meier method.

RESULTS

An average of 20 lymph nodes (range, 9-57; median, 19 ) were dissected from 82 patients. Of the 82 patients, 49 (59.8%) were at stage N1, 21 (25.6%) at stage N2. Two (2.4%) patients died 2 and 3 days after operation. No bronchial anastomotic leakage occurred. The 1-, 2-, 3-, and 5-year survival rates were 78.4%, 52.5%, 39.1%, and 23.4%, respectively, with a median survival of 26 months. There were no significant differences in 1-, 3-, and 5-year survival rates between male and female patients, or between the patients aged of <60 and > or =60. The differences in 1-, 3-, and 5-year survival rates among N1(-) N2(-), N1 (+) N2(-), N2(+) patients, and among stageI, II, IIIA, IIIB patients were significant (P<0.01).

CONCLUSIONS

Perioperative mortality and the incidence of anastomosis-related complications for lung cancer patients after sleeve resection are low. Sleeve resection is an alternative to pneumonectomy for certain indications. Systematic lymph node dissection does not increase operative complications and mortality. The survival of lung cancer patients after sleeve resection is conelated to lymph node metastasis and clinical stage, but has no correlation to gender or age.

MMP2 promoter polymorphism (C-1306T) and risk of recurrence in patients with hepatocellular carcinoma after transplantation

Genetic variants in matrix metalloproteinase (MMP) gene may influence the biological function of these enzymes and change their role in carcinogenesis and progression. The effect of MMP2 C-1306T and MMP9 C-1562T polymorphisms on genetic susceptibility has been investigated in various kinds of cancer. However, the relationship between these polymorphisms and risk of recurrence of hepatocellular carcinoma (HCC) after liver transplantation (LT) has not been reported. The present study was designed to investigate the association of these two loci with the risk of HCC recurrence in 93 HCC patients treated with LT. Genotyping was performed using direct DNA sequencing. For MMP2 C-1306T variant, patients with CT heterozygous conferred a 58% reduction in recurrence risk (risk ratio: 0.419; 95% confidence interval: 0.177-0.994). The mean recurrence-free survival for CT genotype was significantly longer than that for homozygous CC patients (30.4 vs 19.3 months, p = 0.019). However, no association was found between MMP9 C-1562T polymorphisms and recurrence of HCC (p = 0.259). These findings suggest that MMP2 promoter polymorphisms may provide some predictive value for HCC recurrence after LT.

[Ivor Lewis esophagectomy with two-field lymph node dissection for squamous cell carcinoma of the lower thoracic esophagus]

BACKGROUND & OBJECTIVE

Esophagectomy with local regional lymph node dissection is the main treatment for lower thoracic esophageal carcinoma. This study was to assess the clinical outcomes of Ivor Lewis esophagectomy with two-field lymph node dissection for squamous cell carcinoma of the lower thoracic esophagus.

METHODS

Clinical data of 73 patients with squamous cell carcinoma of the lower thoracic esophagus, who underwent Ivor Lewis esophagectomy with two-field lymph node dissection from Jan. 1998 to Dec. 2001, were analyzed retrospectively. Kaplan-Meier method was used for survival analysis.

RESULTS

The morbidity of postoperative complications was 15.1% with a 2.7% mortality rate. The lymph node metastasis rate was 71.2%; the metastasis rate of the upper mediastinal nodes was 17.8%. Of the 73 patients, 5 were at stage I, 35 at stage II, 32 at stage III, and 2 at stage IV. The overall 5-year survival rate was 23.3%. The 5-year survival rate was 38.1% for N0 patients and 17.3% for N1 patients (P<0.01), and was 31.2% for stage IIa patients, 27.8% for stage IIb patients, and 12.5% for stage III patients (P<0.01).

CONCLUSION

Ivor Lewis esophagectomy with two-field lymph node dissection for squamous cell carcinoma of the lower thoracic esophagus is a safe operation, and may increase the chances of complete resection.

Kinetics of complexing activation by the magnesium ion on green crab (Scylla serrata) alkaline phosphatase

As with mammalian enzymes, green crab (Scylla serrata) alkaline phosphatase can be activated by Mg2+ through a time-dependent course. The activation is mainly a Vmax effect. Tsou's method was used to study the kinetic course of activation. The results show that the enzyme was activated by a complexing scheme that had not been previously identified: the enzyme first reversibly and quickly binds Mg2+ and then undergoes a slow reversible course to activation, with a relatively high activation energy (78 +/- 4 kJ/mol) and a slow conformational change. The activation reaction is a single molecule reaction, and the apparent activation rate constant is independent of Mg2+ concentration if the concentration is sufficiently high. The microscopic rate constants of activation and the association constant were determined from the measurements. The proposed scheme may also be applied to the Mg2+ activation mechanism for mammalian enzyme, to explain why the activation rate is time-dependent and not diffusion controlled. Substrate binding was also shown to affect the activation rate constant.

In vitro spontaneous parthenogenetic activation of golden hamster oocytes

Parthenogenetic activation is a major hurdle to be cleared for the examination of the human sperm chromosome after intracytoplasmic injection (ICSI) into golden hamster oocytes. Various factors that affect spontaneous activation of hamster oocytes were, therefore, investigated in this study. We collected cumulus-oocyte complexes (COC) from the oviducts of superovulated females and washed them thoroughly with Ca2+-containing or Ca2+-free TALP-HEPES medium (handling media). We cultured oocytes with intact cumulus or those without cumulus (removed by previous hyaluronidase treatment) in Ca2+-containing or -free m-TALP-3 for 6 or 12 h before examining for their activation. Among the oocytes recovered 17 h post-hCG, 92-94% were parthenogenetically activated by 6 h of in vitro culture. Activation rate in the oocytes collected at 13.5 h post-hCG (53%) was significantly (P < 0.05) lower than that in the oocytes collected 17 h post-hCG (92%), indicating that the spontaneous activation rate increased as the oocytes became older. Both cumulus-intact and cumulus-free oocytes had similar (P > 0.05) activation rates when cultured in vitro, suggesting that hyaluronidase treatment had no effect on the rate of oocyte activation. Omission of Ca2+ from the handling medium also had no effect on the activation of the oocytes. The rate of spontaneous activation of the oocytes cultured in calcium-free medium for 6 (9%) and 12 h (16%) was significantly (P < 0.01) lower than that (94%) of the control oocytes cultured in Ca2+-containing medium, implying a positive influence of Ca2+ on in vitro activation of hamster oocytes. When we cultured the oocytes first in calcium-free medium for 6 h, and then in calcium-containing medium for 6 h, 94% were activated, which is comparable to the rate for oocytes continuously cultured in Ca2+-containing medium. This indicates that the inhibition of hamster oocyte activation in Ca2+-free medium is reversible and can be used to control spontaneous activation of golden hamster oocytes.

Axillary osmidrosis treated by partial removal of the skin and subcutaneous tissue en bloc and apocrine gland subcision

BACKGROUND

Axillary osmidrosis can be treated with many methods, but local surgery is the treatment of choice.

METHODS

Forty-three patients (32 females and 11 males, average age 20.3 years) were treated by partial removal of the skin and subcutaneous tissue en bloc and follicular clipping of the adjacent area. All operations were performed with local anesthesia in an outpatient setting.

RESULTS

Follow-up ranged from 2 to 47 months (mean: 13.4 months). Forty-one patients (95%) had good results, two (5%) were fair, and none were poor. No recurrences were seen. The wound complication rate was 3.5% for axillae and 7% for patients. There were no scar contractures or limitations of arm abduction.

CONCLUSION

This combined surgical method can eliminate malodor and has a low wound complication and recurrence rate. Though the transient and conspicuous scar is the chief drawback of this method, it is a simple, safe, effective and inexpensive method for treating axillary osmidrosis.

[Exogenous pGH gene localization on chromosomes of the transgenic pigs]

The pUC19-OMT plasmids were cut by Ssp 1 and the products in 900 bp were recovered from low-melting agarose gel and used as probes which were labeled by Digoxigenin. After being denatured, the probes were dropped on the chromosome samples which were also denatured to anneal with them. The anti-digoxigenin antibodies labeled with colloidal gold were used to act with the chromosome samples. In order to localize the exogenous pGH genes(porcine growth hormone gene) on chromosomes detected with optical microscope and improve the sensitivity, digoxigen gold signals are amplified by silver precipitation. After calculating the number of silver grains on every chromosome under the optical microscope, we analyzed the data with statistical methods. The results show that the integrating sites of exogenous pGH genes are very different among the positives. However, it is clear that the exogenous genes in one are always of the tendency to integrate in one specific site on a certain chromosome. These data are of great significance for studying the site-specific integration and the expression efficiency of exogenous genes in the future research.

Inhibition kinetics of green crab (Scylla serrata) alkaline phosphatase by zinc ions: a new type of complexing inhibition

The Tsou method was used to study the kinetic course of inactivation of green crab alkaline phosphatase by zinc ions. The results show that the enzyme was inactivated by a complexing scheme which has not been previously identified. The enzyme first reversibly and quickly binds Zn(2+) and then undergoes a slow reversible course to inactivation and slow conformational change. The inactivation reaction is a single molecule reaction and the apparent inactivation rate constant is for a saturated reaction being independent of Zn(2+) concentration if the concentration is sufficiently high. The microscopic rate constants of inactivation and the association constant were determined from the measurements.

Effects of oxodiperoxovanadate (V) complexes on the activity of green crab (Scylla serrata) alkaline phosphatase

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme that catalyzes the nonspecific hydrolysis of phosphate monoesters. The effects of some pollutants in seawater on the activity of the enzyme will result in the loss of the biological function of the enzyme, which will affect the exuviating crab shell and threaten the survival of the animal. In the present paper, the effects of four oxodiperoxovanadate (V) complexes on the activity of green crab alkaline phosphatase have been studied. The results show that these vanadate derivatives can lead to reversible inactivation. The equilibrium constants for binding of inhibitors with the enzyme and/or the enzyme-substrate complexes have been determined. The results show that sodium (2,2;-bipyridine)oxodiperoxovanadate, pV(bipy), and potassium oxodiperoxo-(1,10-phenanthroline)vanadate, pV(phen), are competitive inhibitors, while potassium picolinato-oxodiperoxo-vanadate, pV(pic), and oxalato-oxodiperoxovanadate, pV(ox), are mixed-type inhibitors. These results suggest that pV(bipy) is a considerably more potent competitive inhibitor than pV(phen) and that the competitive inhibition effect of pV(pic) is stronger than that of pV(ox), but the non-competitive inhibition effect of pV(ox) is stronger than that of pV(pic).

Kinetics of inhibition of green crab (Scylla serrata) alkaline phosphatase by vanadate

Green crab (Scylla serrata) alkaline phosphatase is a metalloenzyme that catalyzes the nonspecific hydrolysis of phosphate monoesters. The kinetics of inhibition of the enzyme by vanadate has been studied. The time course of the hydrolysis of p-nitrophenyl phosphate catalyzed by the enzyme in the presence of different Na3VO4 concentrations showed that, at each Na3VO4 concentration, the rate decreased with increasing time until a straight line was approached, the slopes of the straight lines being the same for all concentrations. The results suggest that the inhibition of the enzyme by Na3VO4 is a slow, reversible reaction with fractional residual activity. The microscopic rate constants were determined for the reaction of the inhibitor with the enzyme. As compared with Na2HPO4 (Ki = 0.95 mM), Na2HAsO4 (Ki = 1.10 mM), and Na2WO4 (Ki = 1.55 mM), the results suggest that Na3VO4 (Ki = 0.135 mM) is a considerably more potent inhibitor than other inhibitors.

Effect of metal ions on the activity of green crab (Scylla serrata) alkaline phosphatase

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme, which catalyzes the nonspecific hydrolysis of phosphate monoesters. The present paper deals with the study of the effect of some kinds of metal ions on the enzyme. The positive monovalent alkali metal ions (Li(+), Na(+) and K(+)) have no effect on the enzyme; positive bivalent alkaline-earth metal ions (Mg(2+), Ca(2+) and Ba(2+)) and transition metal ions (Mn(2+), Co(2+), Ni(2+) and Cd(2+)) activate the enzyme; heavy metal ions (Hg(2+), Ag(+), Bi(2+), Cu(2+) and Zn(2+)) inhibit the enzyme. The activation of magnesium ion on the enzyme appears to be a partial noncompetitive type. The kinetic model has been set up and a new plot to determine the activation constant of Mg(2+) was put forward. From the plot, we can easily determine the activation constant (K(a)) value and the activation ratio of Mg(2+) on the enzyme. The inhibition effects of Cu(2+) and Hg(2+) on the enzyme are of noncompetitive type. The inhibition constants have been determined. The inhibition effect of Hg(2+) is stronger than that of Cu(2+).

Inhibition kinetics of green crab (Scylla serrata) alkaline phosphatase activity by dithiothreitol or 2-mercaptoethanol

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme which catalyzes the nonspecific hydrolysis of phosphate monoesters. Some pollutants in seawater affect the enzyme activity causing loss of the biological function of the enzyme, which affects the exuviating crab-shell and threatens the survival of the animal. The present paper studies the effects of thiohydroxyal compounds on the activity of green crab alkaline phosphatase. The results show that thiohydroxyal compounds can lead to reversible inhibition. The equilibrium constants have been determined for dithiothreitol (DTT) and mercaptoethanol (ME) binding with the enzyme and/or the enzyme-substrate complexes. The results show that both DTT and ME are non-competitive inhibitors. The kinetics of enzyme inactivation by ME at low concentrations has been studied using the kinetic method of the substrate reaction. The results suggest that at pH 10.0, the action of ME on green crab ALP is first quick equilibrium binding and then slow inactivation. The microscopic rate constants were determined for inactivation and reactivation. The rate constant of the forward inactivation (k(+0)) is much larger than that of the reverse reactivation (k(-0)). Therefore, when the ME concentration is sufficiently large, the enzyme is completely inactivated.

Kinetics of inhibition of beta-glucosidase from Ampullarium crossean by bromoacetic acid

The kinetics of inhibition of beta-glucosidase from Ampullarium crossean by bromoacetic acid (BrAc) has been studied. The results show that the enzyme can be irreversibly and completely inactivated at high BrAc concentration, while at low BrAc concentration, inhibition of the enzyme is a slow, reversible reaction. The microscopic rate constants for the reactions of BrAc with the enzyme were determined. The presence of the substrate offers obvious protection of the enzyme against inhibition by BrAc. The above results suggest that the histidine residue is essential for activity and is situated at or near the active site of the enzyme.

Effect of methanol on the activity and conformation of acid phosphatase from the prawn Penaeus penicillatus

Prawn (Penaeus penicillatus) acid phosphatase (EC 3.1.3.2) catalyzes the nonspecific hydrolysis of phosphate monoesters. The effects of some pollutants in sea water on the enzyme activity results in the loss of the biological function of the enzyme, which leads to disruption of phosphate metabolism in cells. This paper analyzes the effects of methanol on the activity and conformation of prawn acid phosphatase. The results show that low concentrations of methanol can lead to reversible inactivation. Inhibition of the enzyme by methanol is classified as non-competitive inhibition, and the inhibition constant (Ki) is 8.5%. Conformational changes of the enzyme molecule in methanol solutions of different concentrations were measured using fluorescence emission, differential UV-absorption, and circular dichroism spectra. Increased methanol concentrations caused the fluorescence emission intensity of the enzyme to increase. The ultraviolet difference spectra of the enzyme denatured with methanol had two negative peaks, at 222 and 270 nm, and a positive peak at 236 nm. The changes in the fluorescence and ultraviolet difference spectra reflected the changes of the microenvironments of tryptophan and tyrosine residues of the enzyme. The CD spectrum changes of the enzyme show that the secondary structure of the enzyme also changed some. These results suggest that methanol is a non-competitive inhibitor and the conformational integrity of the enzyme is essential for its activity.

[A study of genetic character and foreign OMT/PGH gene integration in transgenic swine]

By using isotopic and non-isotopic in situ hybridization on chromosomes, the locus on chromosomes of foreign OMT/PGH gene was analyzed in eight transgenic pigs (G0, G1,G2 and G3). The research result is as follows: (1) The foreign genes could integrated on chromosomes of pig and the foreign integrated randomly; (2) the foreign genes integrated on chromosomes were transmissible through generations; (3) the locus on chromosomes of foreign gene was relatively stable in alternation of generations in transgenic swine.

Effect of ethanol on the activity and conformation of Penaeus penicillatus acid phosphatase

The effect of ethanol on the activity of Penaeus penicillatus acid phosphatase has been studied. The results show that ethanol significantly inhibits enzyme activity as a non-competitive inhibitor, with Ki 8.75%. The conformational changes of the enzyme molecule induced by ethanol were followed using fluorescence emission, ultraviolet difference and circular dichroism (CD) spectra. Increasing the ethanol concentration caused the fluorescence emission intensity of the enzyme to increase. The ultraviolet difference spectra of the enzyme denatured with ethanol had two negative peaks at 220 and 278 nm, and a positive peak at 240 nm. Increasing the ethanol concentration produced a small shoulder peak at 287 nm in addition to the increases in the negative magnitudes of the 220 and 278 nm peaks. The changes of the fluorescence and ultraviolet difference spectra reflected the changes of the microenvironments of the tryptophan and tyrosine residues of the enzyme. The CD spectrum changes of the enzyme show that the secondary structure of the enzyme also changed. The results suggest that ethanol is a non-competitive inhibitor and the conformational integrity of the enzyme is essential for its activity.

Kinetics of inhibition of green crab (Scylla serrata) alkaline phosphatase by sodium (2,2'-bipyridine) oxodiperoxovanadate

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme, which catalyzes the nonspecific hydrolysis of phosphate monoesters. The kinetics of inhibition of the enzyme by sodium (2, 2'-bipyridine) oxodiperoxovanadate, pV(bipy), has been studied. The time course of the hydrolysis of p-nitrophenyl-phosphate catalyzed by the enzyme in the presence of different pV(bipy) concentrations showed that at each pV(bipy) concentration, the rate decreased with increasing time until a straight line was approached, the straight line slopes are the same for all concentrations. The results suggest that the inhibition of the enzyme by pV(bipy) is a slow, reversible reaction with fractional remaining activity. The microscopic rate constants are determined for the reaction of inhibitor with the enzyme.

Inhibitors of green crab (Scylla serrata) alkaline phosphatase

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme which catalyzes the nonspecific hydrolysis of phosphate monoesters. The effects of several inhibitors on its activity have been studied. The results show that Na2HPO4, Na2HAsO4 and Na2WO4 are competitive inhibitors, L-phenylalanine is an uncompetitive inhibitor, while L-cysteine is a mixed-type inhibitor. The equilibrium constants were determined for inhibitor binding. The order of potency was Na2HPO4 (KI = 0.95 mM) > Na2AsO4 (1.10 mM) > Na2WO4 (1.55 mM).

Kinetics of inhibition of green crab (Scylla serrata) alkaline phosphatase by L-cysteine

The inhibition of alkaline phosphatase from green crab (Scylla serrata) by L-cysteine has been studied. The results show that L-cysteine gives a mixed-type inhibition. The progress-of-substrate-reaction method previously described by Tsou [(1988), Adv. Enzymol. Related Areas Mol. Biol. 61, 391-436] was used to study the inactivation kinetics of the enzyme by L-cysteine. The microscopic rate constants were determined for reaction of the inhibitor with the free enzyme and the enzyme-substrate complex (ES) The results show that inactivation of the enzyme by L-cysteine is a slow, reversible reaction. Comparison of the inactivation rate constants of free enzyme and ES suggests that the presence of the substrate offers marked protection of this enzyme against inactivation by L-cysteine.