Extracellular vesicles and angiotensin-converting enzyme 2 in COVID-19 disease

Extracellular vesicles(EVs)are membranous vesicular structures released from almost all eukaryotic cell types under different physiological or pathological conditions.Growing evidence demonstrates that EVs can serve as mediators of intercellular communication between donor and recipient cells or microorganism-infected and noninfected cells.Coronavirus disease 2019(COVID-19)disease is caused by infection of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)of host cells in the respiratory system and various extra-pulmonary tissue/organs,resulting in complications of multiple organ systems.As the cell surface receptor,angiotensin-converting enzyme 2(ACE2)mediates cellular entry of SARS-CoV-2 into the host cells in patients with COVID-19.Recent studies have found that ACE2 can be released with EVs,which have been shown to interfere with the entry of the virus into host cells and thus may be involved in COVID-19 pathophysiology.In addition,ACE2,neprilysin(NEP),and thimet oligopeptidase(TOP)are the key enzymes that regulate angiotensin metabolism by converting angiotensin II or angiotensin I to angiotensin 1-7,the latter of which has protective effects in counterbalancing the harmful effects of angiotensin II in COVID-19 disease.This review summarizes the recent research progress regarding EV-associated ACE2,NEP,and TOP and the perspectives of their potential involvement in the pathophysiology of COVID-19 disease.

Aβ-Carotene Ketolase Gene NfcrtO from Subaerial Cyanobacteria Confers Drought Tolerance in Rice

Nostoc flagelliforme is a terrestrial cyanobacterium that can resist many types of stressors,including drought,ultraviolet radiation,and extreme temperatures.In this study,we identified the drought tolerance gene NfcrtO,which encodes aβ-carotene ketolase,through screening the transcriptome of N.flagelliforme under water loss stress.Prokaryotic expression of NfcrtO under 0.6 mol/L sorbitol or under 0.3 mol/L NaCl stress significantly increased the growth rate of Escherichia coli.When NfcrtO was heterologously expressed in rice,the seedling height and root length of NfcrtO-overexpressing rice plants were significantly higher than those of the wild type(WT)plants grown on½Murashige and Skoog solid medium with 120 mmol/L mannitol at the seedling stage.Transcriptome analysis revealed that NfcrtO was involved in osmotic stress,antioxidant,and other stress-related pathways.Additionally,the survival rate of the NfcrtO-overexpression lines was significantly higher than that of the WT line under both hydroponic stress(24%PEG and 100 mmol/L H_(2)O_(2))and soil drought treatment at the seedling stage.Physiological traits,including the activity levels of superoxide dismutase,peroxidase,catalase,total antioxidant capacity,and the contents of proline,trehalose,and soluble sugar,were significantly improved in the NfcrtO-overexpression lines relative to those in the WT line under 20%PEG treatment.Furthermore,when water was withheld at the booting stage,the grain yield per plant of NfcrtO-overexpression lines was significantly higher than that of the WT line.Yeast two-hybrid analysis identified interactions between NfcrtO and Dna J protein,E3 ubiquitin-protein ligase,and pyrophosphate-energized vacuolar membrane proton pump.Thus,heterologous expression of NfcrtO in rice could significantly improve the tolerance of rice to osmotic stress,potentially facilitating the development of new rice varieties.

Expression of interleukin 1β converting enzyme in 5-FU induced apoptosis in esophageal carcinoma cells

AIM To study the role of interleukin 1β converting enzyme (ICE) in antitumor drug induced apoptosis in tumor cells. METHODS Morphological changes in human esophageal carcinoma Eca 109 cells after treated with 5 fluorouracil (5 FU) were observed under light and electron microscope. Expression of ICE in the tumor cells exposed to 5 FU was examined by the immunocytochemical method. RESULTS The cells treated with 5 FU displayed disappearance of nucleoli, chromatin gathering under nuclear envelope, karyorrhexis, budding and the formation of apoptotic bodies. The expression of ICE was negative in control cells, and 5 FU could induce the ICE expression in Eca 109 cells undergoing apoptosis. The number and the staining intensity of positive cells increased with the extension of action time. CONCLUSION 5 FU may induce apoptosis in human esophageal carcinoma Eca 109 cells; ICE gene may be involved in the regulation of 5 FU induced apoptosis; and ICE protein may mediate apoptosis induced by 5 FU.

A Novel Angiotensin I Converting Enzyme Inhibitory Peptide from the Milk Casein:Virtual Screening and Docking Studies

Angiotensin I converting enzyme （ACE） plays an important physiological role in the regulation of hypertension. In this study, we applied virtual screening to discover a novel angiotensin I converting enzyme inhibitory peptides from milk casein. One potential hit was identified based on docking scores, subsequently confirmed by activity studies in vitro （IC50=20.85 μmol L-1）. The proposed peptide in this study contains a unique sequence, Lys-Val-Leu-Ile-Leu-Ala. Moreover, we performed the docking studies to understand the binding mode between the enzyme and peptide hit.

Effects of Yinchenhao Decoction on Self-regulation of Renin-angiotensin System by Targeting Angiotensin Converting Enzyme 2 in Bile Duct-ligated Rat Liver

Summary： In order to investigate whether Yinchenhao decoction （YCHD） attenuates hepatic fibro- genesis in the bile duct ligation （BDL） model via recovering and restoring the self-regulation and bal- ance of the renin-angiotensin system （RAS）, 33 specific-pathogen-free （SPF） male Sprague-Dawley rats with common BDL and scission were randomly divided into five groups as follows： G1, the sham group （n=4）; G2, BDL 7-day group （n=5）; G3, BDL＋YCHD 430 mg/mL （n=8）; G4, BDL＋losartan 0.65 mg/mL （ARB group, n=8）; G5, model group （BDL without any treatment, n=8）. YCHD and losartan （10 mL.kgl.day-1） were given by gastric gavage for 16 days following BDL in G3 and G4 groups, respec- tively. The effect of YCHD on liver fibrosis and the detailed molecular mechanisms were assessed by liver function including total bilirubin （TBIL）, direct bilirubin （DBIL）, indirect bilirubin （IDBIL）, alanine aminotransferase （ALT）, and aspartate aminotransferase （AST）. Histological changes were ob-. served by transmission electron microscopy （TEM） and Masson trichrome staining. Western blotting was used to detect the protein expression level of the renin-angiotensin system （RAS） components in- cluding angiotensin converting enzyme （ACE）, angiotensin II type 1 receptor （AT1R）, ACE2, angio- tensin II （Ang II） as well as transforming growth factor 131 （TGF131）. The experimental data were ana- lyzed by principle component analytical method of pattern recognition. The results showed that bio- chemically, serum TBIL, DBIL, IDBIL, ALT and AST levels were markedly increased following BDL as compared with the sham group （P〈0.05）. Serum TBIL, IDBIL and DBIL levels in G3 group were dramatically decreased as compared with G5 and G4 groups （P〈0.05）. Serum AST level in G3 was sig- nificantly lowered than in G5 group （P〈0.05）, but there was no significant difference in ALT among G3, G4 and G5 groups （P〉0.05）. Histologically, livers in G3 group showed less hepatocytes necrosis, less bile duct hyperplasia and less collagen formation than in G4 and G5 groups. The protein expression lev- els of ACE2, ACE, Ang II, AT1R and TGF131 in G2, G3 and G4 groups were significantly higher than in sham group （P〈0.05）, and lower than in G5 group （P〈0.05）. However, the differences among G2, G3 and G4 groups were not significant （P〉0.05）. ACE2 protein expression in G3 group was significantly higher than in G2 group （P〈0.05） and there was no significant difference in comparison with G4 group （P〉0.05）. Moreover, the protein expression of TGF131 in G3 group was significantly lower than in G5 and G4 groups （P〈0.05）. Our findings suggest that the antifibrotic effects of YCHD may be associated with the decreased classical RAS pathway components and TGFI31 downexpression so as to recover and rebuild self-regulation of the RAS by elevating the protein expression of ACE2.

Angiotensin-converting enzyme and bradykinin gene polymorphisms and cough:A meta-analysis

AIM:To evaluate the association between genetic polymorphisms and angiotensin converting enzyme in-hibitor (ACEI)-related cough,and the race-or ethnicity-related difference in the prevalence of cough attributed to ACEI therapy.METHODS:We conducted a search in PubMed,EM-BASE,Cinahl,and the Cochrane Database without language limitation.A database of 11 studies on ACEI-related cough,with detailed information regarding ACE I/D or bradykinin B 2 receptor polymorphisms,was created.Eligible studies were synthesized using meta-analysis methods,including cumulative meta-analysis.A subgroup analysis was also performed using ethnicity.RESULTS:Six studies were included on ACE I/D poly-morphism (398 Caucasians,723 East Asians),and three studies were included on bradykinin B 2 receptor poly-morphism (300 East Asians).The distribution of ACE genotypes showed significant differences in the entire population (P=0.004) and in East Asians (P=0.005)but not in Caucasians (P=0.23).Allelic frequencies of ACE showed significant differences in East Asians [odds ratio (OR)=1.49 (1.11-2.02)].The meta-analysis with a random effects model showed a significant associa-tion between ACE allele I/D and ACEI-related cough [random effects (RE) OR=1.49 (1.11-2.02),P=0.009] in East Asians,but not in Caucasians [RE OR=0.90 (0.60-1.35)].The allelic frequencies of the bradykinin B 2 receptor gene were significantly different [OR=2.25 (1.42-3.57)].The distributions of the T/C genotypes of the bradykinin B 2 receptor gene were significantly dif-ferent (χ 2=8.366,P=0.015).The meta-analyses re-vealed that there was a significant association between the bradykinin B 2 receptor allele and ACEI-related cough in East Asians [RE OR=2.29 (1.42-3.69),P=0.001].CONCLUSION:ACE I/D and Bradykinin B 2 receptor polymorphisms contributed to the risk of ACEI-related cough in East Asians,but a negative association be-tween ACE I/D polymorphism and ACEI-related cough was observed in Caucasians.

Effect of angiotensin Ⅱ type 1 receptor blocker and angiotensin converting enzyme inhibitor on the intraocular growth factors and their receptors in streptozotocin-induced diabetic rats

AIM： To investigate the effect of angiotensin II type 1 receptor blocker （ARB） and angiotensin converting enzyme inhibitor （ACEI） on intraocular growth factors and their receptors in streptozotocin-induced diabetic rats. METHODS： Forty Sprague-Dawley rats were divided into 4 groups： control, diabetes mellitus （DM）, candesartan- treated DM, and enalapril-treated DM （each group, n---10）. After the induction of DM by streptozotocin, candesartan [ARB, 5 mg/（kg · d）] and enalapril [ACEI, 10 mg/（kg · d）] were administered to rats orally for 4Wko Vascular endothelial growth factor （VEGF） and angiotensin II （Ang II） concentrations in the vitreous were measured using enzyme-linked immunosorbent assays, and VEGF receptor 2 and angiotensin II type 1 receptor （ATIR） levels were assessed at week 4 by Western blotting. RESULTS： Vitreous Ang II levels were significantly higher in the DM group and candesartan-treated DM group than in the control （P=0.04 and 0.005, respectively）. Vitreous ATIR increased significantly in DM compared to the other three groups （P〈0.007）. Candesartan-treated DM rats showed higher vitreal ATIR concentration than the enalapril-treated DM group and control （P〈0.001 and P=0.005, respectively）. No difference in vitreous Ang II and ATIR concentration was found between the enalapril- treated DM group and control. VEGF and its receptor were below the minimum detection limit in all 4 groups. CONCLUSION： Increased Ang II and ATIR in the hyperglycemic state indicate activated the intraocular renin-angiotensin system, which is inhibited more effectively by systemic ACEI than systemic ARB.

Serum levels of angiotensin converting enzyme as a biomarker of liver fibrosis

The renin angiotensin system(RAS) is classically conceived as a circulating hormonal system involved in blood pressure control and hydroelectrolyte balance. The discovery that RAS components are locally expressed in a wide range of organs and tissues,including the liver,pointed to a role for this system in the pathogenesis of several conditions including hepatic fibrosis and cirrhosis. It has been widely reported that the classical RAS axis composed by the angiotensin converting enzyme(ACE)-angiotensin(Ang) Ⅱ-Ang type 1(AT1) receptor mediates pro-inflammatory,pro-thrombotic,and pro-fibrotic processes. On the other hand,the alternative axis comprising ACE2-Ang-(1-7)-Mas receptor seems to play a protective role by frequently opposing Ang Ⅱ action. Chronic hepatitis B(CHB) is one of the leading causes of liver fibrosis,accounting for the death of nearly one million people worldwide. Liver fibrosis is a key factor to determine therapeutic interventions for patients with CHB. However,the establishment of non-invasive and accurate methods to detect reversible stages of liver fibrosis is still a challenge. In an elegant study published in the 36 th issue of the World Journal of Gastroenterology,Noguchi et al showed the predictive value of serum ACE levels in detecting not only advanced stages of liver fibrosis but also initial and intermediate fibrotic stages. The serum levels of ACE might represent an accurate,non-invasive,widely available,and easy method to evaluate fibrosis related to CHB. Moreover,therapies involving the inhibition of the classical RAS axis components might be promising in the control of CHB-related liver fibrosis.

Origin and genomic characteristics of SARS-CoV-2 and its interaction with angiotensin converting enzyme type 2 receptors, focusing on the gastrointestinal tract

The emergence of coronavirus disease-2019 induced by a newly identified bcoronavirus, namely severe acute respiratory syndrome coronavirus 2(SARSCoV-2) has constituted a public health emergency. Even though it was considered a zoonotic disease, the virus has also spread among humans via respiratory secretions. The expression and distribution of angiotensin converting enzyme type 2(ACE2) in various human organs might also show other possible infection routes. High ACE2 ribonucleic acid expression has been identified in the gastrointestinal tract(GI) indicating its importance as a possible infection pathway of SARS-CoV-2. ACE2 induces viral entry into the host and most importantly has been found to be associated with the function of the gut. Its deficiency has been implicated in several pathologies such as colorectal inflammation. The renin-angiotensin system(RAS) is an essential regulatory cascade operating both at a local tissue level and at the systemic or circulatory level. The RAS may be important in the pathogenesis of chronic liver disease and is associated with the up-regulation of ACE2. Thus, the aim of this review is firstly, the analysis of some important general and genome characteristics of SARS-CoV-2 and secondly, and most importantly, to focus on the utility of ACE2 receptors in both SARS-CoV-2 replication and pathogenesis, especially in the GI tract.

Effect of angiotensin converting enzyme gene I/D polymorphism in South Indian children with nephrotic syndrome

Nephrotic syndrome is one of the most common childhood kidney diseases. It is mostly found in the age group of 2 to 8 years. Around 10%-15% of nephrotic syndrome cases are non-responders of steroid treatment(SRNS).Angiotensin converting enzyme(ACE)(I/D) gene association studies are important for detecting kidney disease and herein we assessed the association of ACE(I/D) polymorphism with nephrotic syndrome in South Indian children. We recruited 260 nephrotic syndrome(162 boys and 98 girls) and 218(140 boys and 78 girls) control subjects. ACE I/D polymorphism was analyzed by PCR using genotype allele specific primers. In ACE(I/D), we did not find significant association for the ungrouped data of nephrotic syndrome children and the control subjects. Kidney biopsies were done in 86 nephrotic syndrome cases(minimal change disease, n = 51;focal segmental glomerulosclerosis, n = 27;diffuse mesangial proliferation, n = 8). We segregated them into the minimal change disease/focal segmental glomerulosclerosis groups and observed that the ACE’D’ allele was identified with borderline significance in cases of focal segmental glomerulosclerosis and the ’Ⅰ’ allele was assessed as having very weak association in cases of minimal change disease. ’Ⅱ’ genotype was weakly associated with minimal change disease. Gender specific analysis revealed weak association of’ID’ genotype with female nephrotic syndrome in females. Dominant expression of DD genotype was observed in males with nephrotic syndrome. Our finding indicated that ACE(I/D) has moderate association with focal segmental glomerulosclerosis. However, due to the limited number of biopsy proven focal segmental glomerulosclerosis subjects enrolled, further studies are required to confirm these results.

Correlation of angiotensin converting enzyme gene polymorphism with perioperative myocardial protection under extracorporeal circulation

Objective:To observe the expression of angiotensin converting enzyme(ACE),angiotensinⅡ(AngⅡ),cardiac troponin 【cTnⅠ),creatine kinase isozymes(CK-MB) and muscle red protein(Myo) after cardiopulmonary bypass(CPB),and to investigate the association of polymorphisms in angiotensin converting enzyme genes and myocardial injury.Methods:Sixty-three patients suffered from rheumatic mitral stenosis and scheduled for mitral valve replacement with CPB, were randomly divided into three groups according polymorphisms in angiotensin converting enzyme genes:typeⅡ,type ID,type DD(each=21).Blood samples were withdrawn from artery before operation(T1),at the beginning of CPB(T2),30 min after CPB(T3),(T4) at the end of CPB(T5), 2 h after CPB(T6),6 h after CPB(17) to measure the expression of ACE,AngⅡ,cTnⅠ,CK-MB, Myo.Results:The level of ACE during and after CPB were significantly higher than those before CPB(P【0.05).As extension of CPB time,the expression of ACE was increased.The level of cTnⅠ, CK-MB,Myo after CPB were significantly higher than those before CPB(P【0.05).The level of cTnⅠ,CK-MB and Myo were highest at T7,T6 and T5 and T7,respectively.The level of ACE,AngⅡ,cTnⅠin patients with DD genotype was significantly higher than the ID andⅡgenotype(P【 0.05).Besides,the level of ACE,AngⅡin patients with ID genotype was significantly higher than the II(P【 0.05).Conclusions:There is certain correlation between CPB perioperative midterm ACE and cTnⅠ,Myo,CK-MB.ACE DD genotype is a susceptibility gene of the CPB perioperative myocardial injury.

Long-term Administration of Angiotension-Converting Enzyme Inhibitor Improves the Outcome of Chronic Heart Failure in Senile Patients

One hundred and sixteen senile patients (older than 65 years) with chronic heart failure (CHF) were analyzed retrospectively in order to verify if old patients with CHF would benefit from long term (one year) angiotension converting enzym e inhibitor (ACEI) treatment. The frequency of drugs (including ACEI, digitalis and diuretic) used was stratified into four degrees accordingly. Develop ment of the CHF was scored with regard to relapse rate and severity of this dise ase. Stepwise regression analysis was applied to explore the relationship betwee n the scored outcome of CHF and the frequency of individual drug administration. A significant relationship of the scored outcome of CHF to the frequency of ACE I usage but not to digitalis nor to diuretics was found (partial coefficient of the correlation r =0.42, P =0.002). It was concluded that the long term a dministration of ACEI improves the outcome of CHF in senile patients.

POLYMORPHISM OF ANGIOTENSIN CONVERTING ENZYME GENE AND GENETIC SUSCEPTIBILITY TO ASTHMA WITH FAMILIAL AGGREGATION

Angiotensin converting enzyme (ACE) plays a key role in the metabolism of angiotensin Ⅱ (AT Ⅱ) and inactivation of bradykinins and tachykinins, which are potent bronchialconstrictors and mediators of inflammation asthma, and ACE is heavily expressed in the lungs. An insertion deletion (D/I) polymorphism of ACE gene has been shown to be associated with levels of ACE. We investigate whether the polymorphism of ACE gene is associated with asthma and bronchial responsiveness. Methods. A case control study was carried out in 50 asthmatics, 7 families with at least 2 asthmatic individuals, and 50 healthy subjects. The insertion/deletion (I/D) polymorphism of ACE gene was amplified by polymerase chain reaction (PCR). Methacholine brocho provocation and pulmonary function tests were performed in all asthmatics. Results. There was an higher gene frequency of DD genotype of ACE gene in asthmatic subjects and families individuals compared with healthy subjects (46%, 53% vs 16%, P<0 05; odd ratio 4 98). Anhigher prevalence of DD genotype of ACE was in patients with bronchial hyperresposiveness (BHR) (67%vs 33%, P<0 05; odd ratio 3 8). Accordingly, the mean values of FEV 1% and FEV 1/FVC were higher in asthmatics carrying non DD alleles than patients with DD genotype (73 78% vs 56 56%, P<0 05; 79 19% vs 69 29%, P<0 05, respectively). Conclusion. These results suggested that DD allele of ACE genotype was significantly involved in genetic susceptibility to asthma. DD genotype of ACE might be a risk factor for the degree of airway obstruction, it could also be implicated in pathogenesis of bronchial hyperresponsiveness.

Role of angiotensin converting enzyme and angiotensinogen gene polymorphisms in angiotensin converting enzyme inhibitor-mediated antiproteinuric action in type 2 diabetic nephropathy patients

AIM To investigate the role of genetic variants of angiotensin converting enzyme(ACE) and angiotensinogen(AGT) genes in the antiproteinuric efficacy of ACE inhibitor therapy in diabetic nephropathy(DN) patients.METHODS In the present study, 270 type 2 diabetes mellitus patients with nephropathy were enrolled and treated with ACE inhibitor(ramipril) and followed at 6 mo for renal function and albumin excretion by estimating serum creatinine, end stage renal disease, and albumin/creatinine ratio(ACR) in urine. Genotyping of ACE I/D and AGT M235 T polymorphisms were performed by using primer specific polymerase chain reaction(PCR) and PCR-RFLP techniques, respectively. RESULTS Forty-eight percent of DN patients(responders) benefited with respect to proteinuria from ACE inhibitor therapy at 6 mo follow-up. A significant reduction in ACR was observed after 6 mo treatment with ACE inhibitor irrespective of whether DN patients were micro-albuminuric(≥ 30 and < 300 mg/g creatinine) or macro-albuminuric(≥ 300 mg/g creatinine) at the time of enrollment. However, macro-albuminuric patients(55%) showed better response to therapy. A reduction in urinary ACR was found independent of genotypes of ACE I/D and AGT M235 T polymorphisms although macro-albuminuric patients having TT genotype showed statistically insignificant increased response(72%). CONCLUSION ACE inhibitor therapy reduced urinary ACR by ≥ 30% in 50% of DN patients and the response is independent of ACE I/D and AGT M235 T polymorphisms.

Liquid Chromatographic Assay of Peptides Activity with Inhibiting Angiotensin Converting Enzyme

A rapid, simple and interference-free method was developed to evaluate the inhibitory activity of hydrolyzed peptides from egg white protein against the angiotensin-converting enzyme. The total reaction volume was 60 μL, saving the cost. The assay was based on a HPLC separation and quantification of the synthetic substrate hippuryl-L-histidyl-L-leucine and its hydrolyzed product-hippuric acid; the separation was performed on a C18 column eluted by a mobile phase of acetonitrile/water（0.5% TFA） at a volume ratio of 25：75. At a signal to noise ratio（S/N） of 10, the detective limit of the quantitation of hippuric acid was （0.4600±0.0097） μmol/L. The standard curve shows a linear response with a slope of 49488 and a correlation coefficient of 0.9995. The assay was adequate for the study of ACE inhibition by Captopril and peptides derived from food protein, and showed a very good correlation with the previous methods.

Expression of tumor necrosis factor-alpha converting enzyme in liver regeneration after partial hepatectomy

AIM:To study the expression of tumor necrosis factor- alpha converting enzyme (TACE) and evaluate its significance in liver regeneration after partial hepatectomy in vivo. METHODS: Male SD rats underwent 70% partial hepatec- tomy. The remaining liver and spleen tissue samples were collected at indicated time points after hepatectomy. TACE expression was investigated by Western blotting, immunohistochemistry, and serial section immunostaining. RESULTS: Expression of TACE in liver and spleen tissues after partial hepatectomy was a time-dependent alteration, reaching a maximal level between 24 and 48 h and remaining elevated for more than 168 h. TACE protein was localized to mononuclear cells (MNC), which infiltrated the liver from the spleen after hepatectomy. The kinetics of TACE expression was in accordance with the number of TACE-staining MNCs and synchronized with those of transforming growth factor-α (TGFα). In addition, TACE-staining MNC partially overlapped with CD3+ T lymphocytes. CONCLUSION: TACE may be involved in liver regenera- tion by pathway mediated with TGFα-EGFR in the cell- cycle progressive phase in vivo. TACE production and effect by paracrine may be a pathway of involvement in liver regeneration for the activated CD3+ T lymphocytes.

Comparison of Properties of Tumor Necrosis Factor-α Converting Enzyme (TACE) and Some Matrix Metalloproteases (MMPs) in Catalytic Domains

The crystal structural data of TACE, MMP-1, MMP-2, MMP-3 and MMP-9 were obtained from PDB database, and then their catalytic domains＇ properties including conformation, molecular surface hydrophobicity and electrostatic potential were analyzed and compared by using Insight II molecular modeling software. It was found that the conformation and molecular surface hydrophobicity of catalytic domains of TACE and MMPs were not obviously different, but the molecular surface electrostatic potential of catalytic domain of TACE＇ and MMPs had obvious differences. The findings are helpful in the Rational Drug Design of TACE selective inhibitor.

Expression of Extracellular Signal-regulated Kinase and Angiotensin-converting Enzyme in Human Atria during Atrial Fibrillation

In order to investigate the changes in the expression of extracellular signal regulated kinase (ERK1/ERK2) and angiotensin converting enzyme (ACE) in the patients with atrial fibrillation (AF), 52 patients with rheumatic heart diseases were examined. Nineteen patients had chronic persistent AF (AF≥6 months, CAF), 12 patients had paroxymal AF (PAF) and 21 patients had no history of AF. The ERK expression was detected at the mRNA level by reverse transcription polymerase chain reaction, at the protein level by Western blotting and at atrial tissue level by immunohistochemistry. ERK activating kinases (MEK1/2) and ACE were determined by Western blotting techniques. The expression of ERK2 mRNA was increased in the patients with CAF (74±19 U vs sinus rhythm: 32±24 U, P <0.05). Activated ERK1/ERK2 and MEK1/2 were increased to more than 150 % in the patients with AF compared to those with sinus rhythm. No significant difference between CAF and PAF was found. The expression of ACE was three fold increased in the patients with CAF compared to those with sinus rhythm. Patients with AF showed an increased expression of ERK1/ERK2 in atrial interstitial cells and marked atrial fibrosis. An ACE dependent increase in the amounts of activated ERK1/ERK2 in atrial interstitial cells may be one of molecular mechanisms for the development of atrial fibrosis in the patients with AF. These findings may have important impact on the treatment of AF.

Drying Technology of Angiotensin Converting Enzyme Inhibitory Peptide Derived from Bovine Casein

Drying technology of angiotensin converting enzyme （ACE） inhibitory peptides derived from bovine casein was investigated. No significance was observed on ACE inhibitory activity of products prepared by spay drying and freeze drying （P〉0.05）. Spay drying was the best drying process for practical industry production. The inlet temperature ranged from 140℃ to 160℃ and the exit temperature ranged from 70 ℃ to 90 ℃ during the spay drying process. Under the optimal conditions, scale-up of angiotensin converted enzyme inhibitory peptide from 1 L to 10 L and the experiment was successively conducted. Peptide yield was 29% and half inhibitory concentration （IC50） was 0.53 g. L^-1.

Purification and Characterization of Angiotensin I Converting Enzyme Inhibition Peptides from Sandworm Sipunculus nudus

Three angiotensin I converting enzyme(ACE) inhibition peptides were isolated from sandworm Sipunculus nudus protein hydrolysate prepared using protamex. Consecutive purification methods, including size exclusion chromatography and reverse-phase high performance liquid chromatography(RP-HPLC), were used to isolate the ACE inhibition peptides. The amino acid sequences of the peptides were identified as Ile-Asn-Asp, Val-Glu-Pro-Gly and Leu-Ala-Asp-Glu-Phe. The IC_(50) values of the purified peptides for ACE inhibition activity were 34.72 μmol L^(-1), 20.55 μmol L^(-1) and 22.77 μmol L^(-1), respectively. These results suggested that S. nudus proteins contain specific peptides that can be released by enzymatic hydrolysis. This study may provide an experimental basis for further systematic research, rational development and clinical utilization of sandworm resources.