Abstract P276: Tissue Primacy of Chymase as an Angiotensin II-forming Enzyme from Angiotensin-(1-12)

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Sarfaraz Ahmad ◽  
Jasmina Varagic ◽  
Che P Cheng ◽  
James F Collawn ◽  
Louis J Dell’Italia ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Left Ventricle ◽  
Rat Heart ◽  
Kinetic Data ◽  
Plasma Membranes ◽  
Catalytic Efficiency ◽  
Heart Tissue ◽  
Ang Ii ◽  
Efficiency Ratio

Breaking the prevailing acceptance of ACE primacy as the Ang II-forming enzyme, we have demonstrated that cardiac Ang II production in human and rat heart tissues are primarily mediated by chymase. In this study, we compared the affinity of cardiac chymase to generate Ang II from Ang-(1-12) or Ang I in plasma membranes (PMs) isolated from the diseased left atria of humans and SHR left ventricle. PMs (50-100 μg) were exposed to increasing concentrations of either Ang-(1-12) or Ang I substrate (0-300 μM) for 30 min at 37 o C in the presence of lisinopril (200 μM). The K m and V max of human cardiac chymase (Mean ± SE) were 29 ± 0.9 vs 87 ± 8.8 μM and 57 ± 1.4 vs 145 ± 3.7 μM/min/mg for Ang-(1-12) and Ang I substrates, respectively. Similarly, the K m and V max of rat cardiac chymase were 64 ± 6.3 vs 142 ± 17 μM and 13.2 ± 1.3 vs 1.9 ± 0.2 μM/min/mg for Ang-(1-12) and Ang I substrate, respectively. These data suggest that cardiac chymase has a higher affinity for Ang-(1-12) substrate compared to Ang I in both human and rat heart tissues. Further, our kinetic data show that the catalytic efficiency (ratio of V max /K m ) of human and rat chymase were 1.2 and 15.4-fold higher for Ang-(1-12) substrate compared to Ang I. Overall, our findings suggest that Ang-(1-12), rather than Ang I, is the preferred substrate for chymase in the generation of Ang II by human and rat heart tissue.

Abstract 189: Natriuretic Peptide Receptor-A Regulates Angiotensin-II Mediated NF-κB Via Mkp-1 Dependent Pathway

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Gopi Venkatachalam ◽  
Umadevi Subramanian ◽  
Parthasarathy Arumugam ◽  
Elangovan Vellaichamy
Keyword(s):  
Angiotensin Ii ◽  
Cardiac Hypertrophy ◽  
Natriuretic Peptide ◽  
Nuclear Translocation ◽  
Heart Tissue ◽  
Male Rats ◽  
Natriuretic Peptide Receptor ◽  
Ang Ii ◽  
Hypertrophic Growth ◽  
Peptide Receptor

Atrial natriuretic peptide (ANP) exerts local anti-hypertrophic activity in heart tissue by binding to natriuretic peptide receptor (NPR)-A. However, patients with cardiac hypertrophy and congestive heart failure have elevated plasma and tissue levels of ANP and brain natriuretic peptide (BNP) along with Angiotensin II (Ang II). However, the rationale behind the impaired action of ANP in diseased state is not well understood. In this study, we sought to examine the signaling mechanism by which Ang II modulates local anti-hypertrophic effect through inhibition of Npr1 gene, which codes for NPR-A, in the heart. Hence, in vivo , Wistar male rats (n=8/group) were administered suppressor dose of Ang II (50ng/kg/min) for 14 days through implanted mini-osmotic pumps. Also, in vitro , H9C2 (2-1) cardio myofibroblast cells were exposed to Ang II (10 -7 M) for 20 hours. Upon treatment with Ang II, the mRNA and protein expression of Npr1 (p<0.01) was decreased with significant increase in expression of AT1R (p<0.01) in the heart tissues. In addition, a concomitant decrease in cGMP activity and production in isolated heart tissue membrane preparation was found in Ang II infused rats. Moreover, Ang II infusion causes a suppression of MKP-1 phosphatase; while enhancing the phosphorylation of ERK1/2 (p<0.01) and NF-κB (p<0.01) proteins. Similarly, H9C2 cells exhibited the hypertrophic growth with increased expression of AT1R and activation of ERK1/2 proteins on stimulation with Ang II. Furthermore, gene silencing using siRNA-NPR-A prior to Ang II treatment augmented the translocation of NF-κB and activation of ERK1/2 (3-fold). Whereas, pre-treatment with losartan or cGMP analog 8-Br-cGMP, an activator of cGMP-dependent protein kinases, abolished the stimulatory effects of Ang II on AT1R, NF-κB nuclear translocation and phosphorylation of MAPK, but activated the MKP-1 phosphatase. These results suggest that NPRA-cGMP signaling exerts inhibitory effects on Ang II by antagonizing the upstream signaling pathways and by activation of MKP-1 to counter-regulate NF-κB and MAPKs through cGMP dependent mechanism; thereby mediate local anti-hypertrophic activity in cardiac hypertrophy.

Agonist-induced internalisation of the angiotensin II-binding sites from plasma membranes of isolated rat hepatocytes

1997 ◽  
Vol 152 (3) ◽  
pp. 407-412 ◽  
Author(s):  
M Montiel ◽  
M C Caro ◽  
E Jiménez
Keyword(s):  
Plasma Membrane ◽  
Angiotensin Ii ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Binding Capacity ◽  
Rat Hepatocytes ◽  
Receptor Complex ◽  
Ang Ii ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat

Angiotensin II (Ang II) provokes rapid internalisation of its receptor from plasma membranes in isolated rat hepatocytes. After 10 min stimulation with Ang II, plasma membrane lost about 60% of its 125I-Ang II-binding capacity. Internalisation was blocked by phenylarsine oxide (PhAsO), whereas okadaic acid, which markedly reduced the sustained phase of calcium mobilization, did not have a preventive effect on Ang II–receptor complex sequestration. These data suggest that Ang II receptor internalisation is probably independent of a phosphorylation/dephosphorylation cycle of critical serine/threonine residues in the receptor molecule. To establish a relationship between sequestration of the Ang II receptor and the physical properties of the Ang II-binding sites, 125I-Ang II–receptor complex profiles were analysed by isoelectric focusing. In plasma membrane preparations two predominant Ang II-binding sites, migrating to pI 6·8 and 6·5 were found. After exposure to Ang II, cells lost 125I-Ang II-binding capacity to the Ang II–receptor complex migrating at pI 6·8 which was prevented in PhAsO-treated cells. Pretreatment of hepatocytes with okadaic acid did not modify Ang II–receptor complex profiles, indicating that the binding sites corresponding to pI 6·5 and pI 6·8 do not represent a phosphorylated and/or non-phosphorylated form of the Ang II receptor. The results show that the Ang II–receptor complex isoform at pI 6·8 represents a functional form of the type-1 Ang II receptor. Further studies are necessary to identify the Ang II-related nature of the binding sites corresponding to pI 6·5. Journal of Endocrinology (1997) 152, 407–412

scholarly journals Suppressor of Cytokine Signaling 3 Is Induced by Angiotensin II in Heart and Isolated Cardiomyocytes, and Participates in Desensitization

Endocrinology ◽  
2003 ◽  
Vol 144 (10) ◽  
pp. 4586-4596 ◽  
Author(s):  
Vivian C. Calegari ◽  
Rosangela M. N. Bezerra ◽  
Márcio A. Torsoni ◽  
Adriana S. Torsoni ◽  
Kleber G. Franchini ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Rat Heart ◽  
Ventricular Myocytes ◽  
Janus Kinase ◽  
Neonatal Rat ◽  
Cytokine Signaling ◽  
Ang Ii ◽  
Suppressor Of Cytokine Signaling ◽  
Rat Ventricular Myocytes ◽  
Neonatal Rat Ventricular Myocytes

Angiotensin II (Ang II) exerts a potent growth stimulus on the heart and vascular wall. Activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) intracellular signaling pathway by Ang II mediates at least some of the mitogenic responses to this hormone. In other signaling systems that use the JAK/STAT pathway, proteins of the suppressor of cytokine signaling (SOCS) family participate in signal regulation. In the present study it is demonstrated that SOCS3 is constitutively expressed at a low level in rat heart and neonatal rat ventricular myocytes. Ang II at a physiological concentration enhances the expression of SOCS3 mRNA and protein, mainly via AT1 receptors. After induction, SOCS3 associates with JAK2 and impairs further activation of the JAK2/STAT1 pathway. Pretreatment of rats with a specific phosphorthioate antisense oligonucleotide to SOCS3, reverses the desensitization to angiotensin signaling, as detected by a fall in c-Jun expression after repetitive infusions of the hormone. Thus, SOCS3 is induced by Ang II in rat heart and neonatal rat ventricular myocytes and participates in the modulation of the signal generated by this hormone.

Angiotensin II formation in dog heart is mediated by different pathways in vivo and in vitro

1996 ◽  
Vol 271 (2) ◽  
pp. H417-H421 ◽  
Author(s):  
E. Balcells ◽  
Q. C. Meng ◽  
G. R. Hageman ◽  
R. W. Palmer ◽  
J. N. Durand ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Heart Tissue ◽  
Left Ventricular ◽  
In Vivo Studies ◽  
In Vitro Assays ◽  
Ang Ii ◽  
Dog Heart ◽  
Tissue Extracts

Angiotensin-converting enzyme (ACE) inhibitors (I) have beneficial effects that are presumably mediated by decreased angiotensin II (ANG II) production. However, in vitro assays in human heart extracts have demonstrated that > 75% of ANG II-forming enzyme activity was not inhibited by captopril (Cap) and therefore did not appear to be related to ACE but was inhibited by chymostatin, suggesting that it was predominantly chymase-like activity. Previous work in our laboratory has demonstrated a similar relative contribution of ACE and chymase-like activity toward ANG II formation in vitro in dog heart tissue extracts. Accordingly, we compared Cap-inhibitable ANG II formation in vitro in heart tissue of five adult mongrel dogs to the in vivo Cap-inhibitable, ANG II-forming activity across the myocardial bed in four openchest, adult mongrel dogs. In vitro studies demonstrated that only 6 +/- 2% of ANG II formation was inhibited by Cap from heart tissue extracts of the left ventricular midwall. In in vivo studies, ANG I (0.5 nmol/min) followed by ANG I plus the ACE inhibitor Cap (0.1 mumol/min) was infused into the left anterior descending artery, and ANG II was assayed in the proximal aorta and coronary sinus. The arterial-venous (A-V) difference of ANG II across the myocardial circulation increased significantly during ANG I infusion (-13.4 +/- 23.5 to 142.8 +/- 71.4 pg/ml; P < 0.03). Subsequent coinfusion of Cap with ANG I significantly decreased the myocardial A-V difference of ANG II by 60 +/- 18% (P < 0.05). Thus, in contrast to the in vitro situation, ANG II formation in vivo is inhibited significantly by Cap in the normal dog heart. This comparison of in vivo and in vitro conversion of ANG I to ANG II by ACE and chymase-like activity suggests that in vitro assays may underestimate the functional contribution of ACE to intracardiac ANG II formation.

Angiotensin II receptor subtypes in eel (Anguilla anguilla)

1994 ◽  
Vol 12 (1) ◽  
pp. 61-69 ◽  
Author(s):  
S Marsigliante ◽  
T Verri ◽  
S Barker ◽  
E Jimenez ◽  
G P Vinson ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Brush Border ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Anguilla Anguilla ◽  
Receptor Subtypes ◽  
European Eel ◽  
Ang Ii ◽  
Brush Border Membranes ◽  
Renal Brush Border Membrane

ABSTRACT Previous studies have shown the effects of angiotensin II (Ang II) in teleosts, and Ang II-binding sites have also been localized in tissues from rainbow trout. The purpose of this study was to extend these findings and to provide an analysis of Ang II receptor (Ang II-R) isoforms in three tissues obtained from European eel (Anguilla anguilla). Ang II-Rs were identified in eel liver, kidney and intestine membranes by the binding of either 0·5 nmol human 125I-labelled Tyr4-lle5-Ang II/l or increasing concentrations (1–120 nmol/l) of [3,5-3H]Tyr4-Ile5-Ang II. Using an isoelectric focusing technique, two Ang II-binding sites were identified in liver membranes. These migrated to isoelectric points (pI values) 6·5 and 6·7. Seventy per cent of binding to both sites was displaced by a 10 000-fold excess of unlabelled human Ang II. In both whole plasma membranes and brush border membranes from intestine, only one form of the Ang II-R was found, with pI 6·5 and high affinity (Kd=3·4 nmol/l) for the [3,5-3H]Tyr4-Ile5-Ang II. Similarly, only the isoform focusing at pI 6·5 was observed in renal tubular epithelial brush border membranes. Reduction of disulphide bridges with dithiothreitol significantly enhanced Ang II binding to the isoform at pI 6·5 in liver (P<0·05) and kidney (P<0·01), while in liver the binding to the isoform of pI 6·7 was significantly reduced (P<0·001). The data suggest the existence in eel liver of multiple forms of Ang II-R, which may have different functions, while one single form appeared to be present in enterocyte plasma membrane and in renal brush border membrane.

scholarly journals Angiotensin II-dependent phosphorylation at Ser11/Ser18 and Ser938 shifts the E2 conformations of rat kidney Na+/K+-ATPase

2012 ◽  
Vol 443 (1) ◽  
pp. 249-258 ◽  
Author(s):  
Katherine J. Massey ◽  
Quanwen Li ◽  
Noreen F. Rossi ◽  
Raymond R. Mattingly ◽  
Douglas R. Yingst
Keyword(s):  
Angiotensin Ii ◽  
Plasma Membranes ◽  
Rat Kidney ◽  
Second Phase ◽  
Ang Ii ◽  
Wild Type ◽  
Opossum Kidney ◽  
Opossum Kidney Cells ◽  
Two Phases ◽  
At1a Receptor

Kidney plasma membranes, which contain a single α-1 isoform of Na+/K+-ATPase, simultaneously contain two sub-conformations of E2P, differing in their rate of digoxin release in response to Na+ and ATP. Treating cells with Ang II (angiotensin II) somehow changes the conformation of both, because it differentially inhibits the rate of digoxin release. In the present study we tested whether Ang II regulates release by increasing phosphorylation at Ser11/Ser18 and Ser938. Opossum kidney cells co-expressing the AT1a receptor and either α-1.wild-type, α-1.S11A/S18A or α-1.S938A were treated with or without 10 nM Ang II for 5 min, increasing phosphorylation at the three sites. Na+/K+-ATPase was bound to digoxin-affinity columns in the presence of Na+, ATP and Mg2+. A solution containing 30 mM NaCl and 3 mM ATP eluted ~20% of bound untreated Na+/K+-ATPase (Population #1). Pre-treating cells with Ang II slowed the elution of Population #1 in α-1.wild-type and α-1.S938A, but not α-1.S11A/S18A cells. Another 50% of bound Na+/K+-ATPase (Population #2) was subsequently eluted in two phases by a solution containing 150 mM NaCl and 3 mM ATP. Ang II increased the initial rate and slowed the second phase in α-1.wild-type, but not α-1.S938A, cells. Thus Ang II changes the conformation of two forms of EP2 via differential phosphorylation.

Empagliflozin treatment does not affect the hypertensive response to Ang II administration to rats but decreases oxidative stress in the arterial wall, and endothelial and cardiac dysfunction

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
C Bruckert ◽  
L Remila ◽  
K Matsushita ◽  
C Auger ◽  
U Houngue ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Blood Pressure ◽  
Angiotensin Ii ◽  
Left Ventricle ◽  
Cardiac Function ◽  
Systolic Blood Pressure ◽  
Sglt2 Inhibitor ◽  
Treated Group ◽  
Funding Source ◽  
Ang Ii

Abstract Background Selective sodium-glucose cotransporter 2 (SGLT2) inhibitors have shown cardiovascular protection in type 2 diabetes patients with established cardiovascular disease independently of glycemic control. Angiotensin II (Ang II) and H2O2 have been shown to be strong inducers of the expression of SGLT2 and 1 in endothelial cells promoting oxidative stress and endothelial dysfunction. Purpose This study examined the cardiovascular protective effect of empagliflozin (empa) in a normoglycemic experimental model of hypertension in the rat. Methods Male Wistar rats received empa (30 mg/kg/day) provided in the diet for 5 weeks. After 1 week, rats underwent sham surgery (sham rats) or surgery with implantation of an osmotic mini-pump infusing Ang II (0.4 mg/kg/d) for 4 weeks. Systolic blood pressure (SBP) was assessed by sphygmomanometry, the cardiac function using echocardiography, the expression level of target proteins by immunofluorescence staining, and the level of oxidative stress using dihydroethidium staining. Results Angiotensin II administration increased systolic blood pressure from about 130 to 180 mmHg, which was not affected by the empa treatment. The 4-week Ang II treatment did not significantly affect the systolic cardiac function (cardiac output, left ventricle ejection fraction) but impaired the diastolic function as indicated by a reduced E' and IVRT values, and an increased E/E' value. The Ang II treatment increased significantly the heart and right ventricle weight whereas the left ventricle + septum weight was slightly but not significantly increased. No such functional and structural changes were observed in the Ang II + empa treatment group. An increased immunofluorescence eNOS signal in the endothelium, and a higher level of ROS throughout the aorta wall were observed in the Ang II-treated group, both of which were significantly reduced in the empa + Ang II-treated group. In the Ang II-treated group, the high level of oxidative stress in the aorta was significantly reduced by the AT1 receptor antagonist losartan, the NADPH oxidase inhibitor VAS-2871, the eNOS inhibitor NG-nitro-L-arginine and also to a greater extent by the selective SGLT2 inhibitor empa compared to the dual SGLT1/2 inhibitor sotagliflozin. Conclusion(s) The present findings indicate that although the empa treatment did not affect the hypertensive response of rats to Ang II, the SGLT2 inhibitor prevented the deleterious impact of Ang II on the diastolic cardiac function and remodeling, and the upregulation of eNOS expression and oxidative stress in the aorta wall. Thus, these findings highlight the protective potential of empa on the cardiovascular system in a normoglycemic hypertensive experimental model. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Boehringer Ingelheim Pharma GmbH & Co KG (Biberach an der Riss, Germany)

Angiotensin II-mediated oxidative stress promotes myocardial tissue remodeling in the transgenic (mRen2) 27 Ren2 rat

2007 ◽  
Vol 293 (1) ◽  
pp. E355-E363 ◽  
Author(s):  
Adam Whaley-Connell ◽  
Gurushankar Govindarajan ◽  
Javad Habibi ◽  
Melvin R. Hayden ◽  
Shawna A. Cooper ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Angiotensin Ii ◽  
Nadph Oxidase ◽  
Heart Tissue ◽  
Left Ventricular ◽  
Cine Mri ◽  
Ang Ii ◽  
Transmission Electron

Angiotensin II (ANG II) contributes to cardiac remodeling, hypertrophy, and left ventricular dysfunction. ANG II stimulation of the ANG type 1 receptor (AT1R) generates reactive oxygen species via NADPH oxidase, which facilitates this hypertrophy and remodeling. This investigation sought to determine whether cardiac oxidative stress and cellular remodeling could be attenuated by in vivo AT1R blockade (AT1B) (valsartan) or superoxide dismutase/catalase mimetic (tempol) treatment in a rodent model of chronically elevated tissue levels of ANG II, the transgenic (mRen2) 27 rat (Ren2). Ren2 rats overexpress the mouse renin transgene with resultant hypertension, insulin resistance, proteinuria, and cardiovascular damage. Young (6–7 wk old) male Ren2 and age-matched Sprague-Dawley rats were treated with valsartan (30 mg/kg), tempol (1 mmol/l), or placebo for 3 wk. Heart tissue NADPH oxidase (NOX) activity and immunohistochemical analysis of subunits NOX2, Rac1, and p22phox, heart tissue malondialdehyde, and insulin-stimulated protein kinase B (Akt) activation were measured. Structural changes were assessed with cine MRI, transmission electron microscopy, and light microscopy. Increases in septal wall thickness and altered systolic function (cine MRI) were associated with perivascular fibrosis and increased mitochondria in Ren2 on light and transmission electron microscopy ( P < 0.05). AT1B, but not tempol, reduced blood pressure ( P < 0.05); significant improvements were seen with both AT1B and tempol on NOX activity, subunit expression, malondialdehyde, and insulin-mediated activation/phosphorylation of Akt (each P < 0.05). Collectively, these data suggest cardiac oxidative stress-induced structural and functional changes are driven, in part, by AT1R-mediated increases in NADPH oxidase activity.

Angiotensin II increases cardiac protein synthesis in adult rat heart

1993 ◽  
Vol 265 (1) ◽  
pp. H238-H243 ◽  
Author(s):  
D. L. Geenen ◽  
A. Malhotra ◽  
J. Scheuer
Keyword(s):  
Heart Rate ◽  
Protein Synthesis ◽  
Angiotensin Ii ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Rat Heart ◽  
Left Ventricular ◽  
Ang Ii ◽  
Adult Rat ◽  
Transplanted Hearts

This study examined the direct effect of angiotensin II (ANG II) on cardiac muscle atrophy previously observed in the denervated rat heart. Rats with transplanted hearts were infused with normal saline (1 microliter/h) or a subpressor dose of ANG II dissolved in saline (3 micrograms.kg-1.h-1) for 1 wk. Left ventricular (LV) mass of transplanted hearts decreased by 29 and 18% in the saline-infused and ANG II-infused groups, respectively (P < 0.05). Total LV protein synthesis of the transplanted heart was 1.4 +/- 0.1 mg.LV-1.day-1 in the saline compared with 2.2 +/- 0.2 mg.LV-1.day-1 in the ANG II (P < 0.05) group. Heart rate and carotid systolic arterial pressures were not affected by ANG II infusion, and the decrease in alpha-myosin heavy chain normally observed in this model was unchanged between the two groups (61 +/- 3 and 66 +/- 1%, saline vs. ANG II). These data demonstrate that ANG II increases total cardiac protein synthesis in the adult heart, leading to an attenuation in cardiac atrophy. The failure of ANG II to prevent the shift from alpha- to beta-myosin heavy chain may be related to its lack of an effect on heart rate, since other interventions that affect myosin isoenzyme distribution also increase heart rate.

Conversion of renin substrate tetradecapeptide to angiotensin II by rat MAB elastase-2

2004 ◽  
Vol 82 (11) ◽  
pp. 1000-1005 ◽  
Author(s):  
Carlos F Santos ◽  
Andrew S Greene ◽  
Maria Cristina O Salgado ◽  
Eduardo B Oliveira
Keyword(s):  
Angiotensin Ii ◽  
Enzymatic Activity ◽  
Catalytic Efficiency ◽  
Inhibitory Effect ◽  
Ang Ii ◽  
Chromogenic Substrates ◽  
Renin Substrate ◽  
New Approach ◽  
Pancreatic Elastase ◽  
Mesenteric Arterial Bed

A new approach for the purification of rat mesenteric arterial bed (MAB) elastase-2 has been developed using the chromogenic substrates N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide and N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide to monitor the enzymatic activity during various stages of purification. The purified enzyme was evaluated in the presence of various inhibitors and confirmed to have angiotensin (Ang) II-forming ability. The active site-directed inhibitor acetyl-Ala-Ala-Pro-Leu-chloromethylketone (100 µmol·L-1), described for human pancreatic elastase-2, abolished the enzymatic activity, confirming that the enzyme is an elastase-2. Chymostatin (100 µmol·L-1), an inhibitor regarded as selective for chymases, also showed a remarkable inhibitory effect (94%), whereas captopril (100 µmol·L-1) had no effect at all on the Ang II-forming activity. The Ang II precursor renin substrate tetradecapeptide (RS-14P) was converted into Ang II by the rat MAB elastase-2 with the following kinetic constants: Km = 124 ± 21 µmol·L-1; Kcat = 629 min-1; catalytic efficiency (Kcat /Km) = 5.1 min-1 µ(mol/L)-1. In conclusion, the strategy for the purification of rat MAB elastase-2 with the chromogenic substrates proved to be simple, rapid, accurate, and highly reproducible; therefore, it can be reliably and conveniently used to routinely purify this enzyme. The kinetic parameters for the formation of Ang II from RS-14P by rat MAB elastase-2 emphasize differences in substrate specificity between this and other Ang II-forming enzymes.Key words: N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide, N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide, elastase-2, angiotensin II, renin substrate tetradecapeptide.

Sign in / Sign up

Export Citation Format

Share Document