Activation of Inactive Plasma Renin: Evidence that Both Cryoactivation and Acid-Activation Work by Liberating a Neutral Serine Protease from Endogenous Inhibitors

1978 ◽  
Vol 55 (s4) ◽  
pp. 135s-138s ◽  
Author(s):  
Steven A. Atlas ◽  
John H. Laragh ◽  
Jean E. Sealey
Keyword(s):  
Serine Protease ◽  
Plasma Renin ◽  
Lima Bean ◽  
Trypsin Inhibitors ◽  
Soya Bean ◽  
Acid Activation ◽  
Alkaline Ph ◽  
Two Phase ◽  
Ph Optimum

1. We have found that ‘acid’-activation of inactive human plasma renin is a two-phase process. About 30% of activation occurs during dialysis to pH 3·3; the remaining 70% occurs at alkaline pH. 2. The ‘alkaline phase’ of activation has a pH optimum between 7·5 and 8·4. It is inhibited by unacidified plasma and by soya-bean or lima-bean trypsin inhibitors. 3. ‘Cryoactivation’ of inactive plasma renin, which occurs at −4°C and alkaline pH, is also inhibited by soya-bean or lima-bean trypsin inhibitors and by the serine protease inhibitors di-isopropylphosphorofluoridate and benzamidine. 4. Thus endogenous neutral serine proteases participate in the activation of inactive plasma renin in vitro. Their action is prevented in the circulation by inhibitors which are inactivated by acid or cold.

Requirements for extracellular metabolism of pulmonary surfactant: tentative identification of serine protease

1992 ◽  
Vol 262 (4) ◽  
pp. L446-L453 ◽  
Author(s):  
N. J. Gross ◽  
R. M. Schultz
Keyword(s):  
Serine Protease ◽  
Surface Area ◽  
Pulmonary Surfactant ◽  
Lamellar Body ◽  
Alveolar Epithelium ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Ph Optimum

Pulmonary alveolar surfactant is secreted by the alveolar epithelium in the form of lamellar bodylike structures that evolve sequentially into tubular myelin and vesicular forms that can be separated by centrifugation. Using an in vitro procedure by which the extracellular metabolism of pulmonary surfactant can be mimicked, namely cyclic variation in surface area, we previously reported that serine protease activity, which we called “convertase,” was required for the conversion of tubular myelin to the vesicular form. In the present studies we explored the biochemical requirements of this activity and sought the enzyme in alveolar products. Convertase activity has unusual requirements; in addition to being dependent on repetitive variations in surface area (cycling), it requires the presence of a high g fraction of lung secretions that is heat stable and not inhibitable by diisopropyl fluorophosphate (DFP) or alpha 1-antitrypsin, both typical serine protease inhibitors. The enzyme does not require calcium ions and has a pH optimum of 7.4. Convertase appears to be a component of surfactant itself because the ability of purified surfactant to convert to the vesicular form on cycling is impaired by pretreating it with DFP. A protein of Mr 75,000 that reacts with DFP and is heat sensitive was found in alveolar lavage, lamellar body preparations, and lung homogenate. It copurifies with lung surfactant in sucrose gradients. A similar DFP-reactive protein was observed in stable human neoplastic peripheral airway cell lines that express type II properties, suggesting that it may be a product of type II cells. We tentatively conclude that surfactant convertase is a 75,000 serine protease that is closely associated with surfactant phospholipid and that may be a product of alveolar type II cells.

scholarly journals Digestibilities of casein and soya-bean protein in relation to their effects on serum cholesterol in rabbits

1985 ◽  
Vol 54 (2) ◽  
pp. 355-366 ◽  
Author(s):  
Christopher J. H. Woodward ◽  
Kenneth K. Carroll
Keyword(s):  
Heat Treatment ◽  
Serum Cholesterol ◽  
Soya Bean ◽  
Pancreatic Enzymes ◽  
Alkaline Ph ◽  
Acid Ph ◽  
Ph Dependent ◽  
Low Solubility ◽  
Bean Protein

1. Diets containing isolated soya-bean protein induce lower levels of serum cholesterol in animals than diets containing casein. Experiments were conducted to investigate whether differences in digestibility of the proteins might explain this effect.2. At pH 8 with pancreatic enzymes or intestinal peptidase, soya-bean protein was hydrolysed in vitro much less rapidly than casein. However, with pepsin (EC3. 4. 23. 1) at acid pH, soya-bean protein was hydrolysed more rapidly than casein.3. These differences in digestibility may be due to pH-dependent changes in solubility of the proteins. Casein and soya-bean protein were most soluble at alkaline and acid pH respectively.4. Heat treatment of the proteins resulted in lower solubilities and digestibilities. Sonication of soya-bean protein at pH 7.8 increased solubility but only slightly raised digestibility.5. When fed to rabbits, enzymically hydrolysed soya-bean protein induced a 2.3-fold higher concentration of serum cholesterol than did intact soya-bean protein. The hypocholesterolaemic effect of soya-bean protein may be partly attributable to its low solubility and digestibility at alkaline pH.

An Endogenous Protease Activating Plasma Inactive Renin

1978 ◽  
Vol 55 (s4) ◽  
pp. 133s-134s ◽  
Author(s):  
B. J. Leckie
Keyword(s):  
Human Plasma ◽  
Serine Protease ◽  
Protease Inhibitors ◽  
Trypsin Inhibitor ◽  
Soya Bean ◽  
Acid Activation ◽  
Bean Trypsin Inhibitor ◽  
Inactive Renin ◽  
Inhibited Acid ◽  
Endogenous Protease

1. The protease inhibitors Trasylol and soya-bean trypsin inhibitor prevented the activation of plasma inactive renin by acid. 2. N-Ethylmaleimide inhibited acid-activation to some extent but o-phenanthroline had no effect. 3. Acid-activation of the inactive renin in human plasma is mediated by a serine protease.

scholarly journals Proteolytic cleavage of haptoglobin occurs in a subcompartment of the endoplasmic reticulum: evidence from membrane fusion in vitro.

1993 ◽  
Vol 123 (2) ◽  
pp. 285-291 ◽  
Author(s):  
M Wassler ◽  
E Fries
Keyword(s):  
Liver Homogenate ◽  
Rat Hepatocytes ◽  
Translation Product ◽  
Alkaline Ph ◽  
Ph Optimum ◽  
Gtp Hydrolysis ◽  
Cytoplasmic Proteins ◽  
Gamma S ◽  
Stimulation Of

The primary translation product of haptoglobin mRNA is a 45-kD polypeptide which is proteolytically cleaved shortly after its synthesis. Previous studies have indicated that the cleavage of this proform of haptoglobin occurs in the ER. In an attempt to characterize the cleaving enzyme, we found that upon incubation of microsomes from rat hepatocytes pulse labeled with [35S]methionine, little cleavage of labeled prohaptoglobin occurred. In contrast, when cells whose cytoplasmic proteins had been released by saponin treatment were incubated, 30-40% of the prohaptoglobin was cleaved. The addition of GTP caused a twofold stimulation, which was abolished by the nonhydrolyzable analog GTP gamma S. With a homogenate of the cells, the addition of GTP resulted in a fourfold stimulation of the degree of cleavage--from 15 to 60%. Differential centrifugation revealed that most of the cleaving activity resided in membranes sedimenting similarly to mitochondria and to a small fraction of the ER. These rapidly sedimenting membranes were therefore prepared from a rat liver homogenate. Upon treatment with high salt, light membranes were released which, when incubated with microsomes of pulse-labeled hepatocytes in the presence of detergent (and in the absence of GTP), induced specific cleavage of prohaptoglobin. The cleaving enzyme had an alkaline pH optimum indicating that it was not of lysosomal origin. These results suggest that cleavage of prohaptoglobin occurs in a subcompartment of the ER. Apparently, the connection between this compartment and the bulk of the ER is broken upon saponin treatment or homogenization but can be reestablished through a process requiring GTP hydrolysis.

Two Forms of Plasma Renin after Activation In Vitro and their Relation to Natural Plasma Renin

1981 ◽  
Vol 61 (s7) ◽  
pp. 295s-298s ◽  
Author(s):  
F. H. M. Derkx ◽  
M. P. A. Schalekamp ◽  
M. A. D. H. Schalekamp
Keyword(s):  
Plasma Renin ◽  
The Other ◽  
Clotting Factor ◽  
Similar Reaction ◽  
Factor Xii ◽  
Ph Optimum ◽  
Renin Substrate ◽  
Active Renin ◽  
Blue Sepharose

1. Inactive renin in human plasma can be activated by pH 3.3-dialysis (generation of acid-activated renin), by clotting factor XII-mediated prekallikrein to kallikrein conversion after pH has been restored to neutral (generation of acid-kallikrein-activated renin) or by the addition of trypsin (generation of trypsin-activated renin). 2. Natural active renin, acid-kallikrein-activated renin and trypsin-activated renin behave similarly during affinity chromatography on Blue-Sepharose CL-6B and during gel filtration on Sephadex G-100. They also show similar reaction kinetics with similar pH-optimum curves when acting on sheep renin substrate. 3. Acid-activated renin is different. It is retained on Blue-Sepharose columns and it is inactivated at neutral pH during incubation at 37°C. This contrasts with the other forms of renin activated in vitro and with natural active renin. The pH-optimum curve of acid-activated renin, when acting on sheep renin substrate, is also different from that of the other forms of active renin. 4. It is to be proven that the renins generated in vitro by neutral serine proteinases are identical with natural active renin, but clearly they bear more resemblance to natural renin than acid- activated renin does. Our preliminary conclusion is that acid-activated renin is a ‘laboratory renin’, which does not circulate in normal peripheral venous plasma.

Activation of Inactive Plasma Renin by Plasma and Tissue Kallikreins

1979 ◽  
Vol 57 (4) ◽  
pp. 351-357 ◽  
Author(s):  
F. H. M. Derkx ◽  
H. L. Tan-Tjiong ◽  
A. J. Man In 'T Veld ◽  
M. P. A. Schalekamp ◽  
M. A. D. H. Schalekamp
Keyword(s):  
Active Form ◽  
Plasma Renin ◽  
Exchange Chromatography ◽  
Acid Activation ◽  
Ph Profile ◽  
Simultaneous Generation ◽  
Inactive Renin ◽  
Fletcher Factor

1. Normal human plasma contains a pro-activator of inactive renin. The pro-activator is activated at physiological pH in plasma that has been pretreated with acid. This activation in vitro leads to the conversion of inactive renin into the active form with simultaneous generation of kallikrein activity. 2. The endogenous activator of inactive renin has the same pH profile and inhibitor spectrum as plasma kallikrein. 3. Inactive renin can also be activated by exposure of plasma to exogenous trypsin, and in normal plasma the quantities of inactive renin that are activated after acidification and with trypsin are identical. Prekallikrein (Fletcher factor)-deficient plasma, however, has much lower renin activity after acidification than with trypsin. Thus acid activation of inactive renin depends on plasma prekallikrein, whereas the action of trypsin is independent of prekallikrein. 4. Highly purified tissue (pancreatic) kallikrein, in a concentration of less than 2 × 10−8 mol/l, activates inactive renin that has been isolated from plasma by ion-exchange chromatography. In this respect it is at least 100 times more potent than trypsin. 5. It is therefore possible that plasma and/or tissue (renal) kallikreins are also involved in the activation of inactive renin in vivo.

Metabolism of phosphoglycerides in E. coli IV. The positional specificity and properties of phospbolipase A

1969 ◽  
Vol 47 (12) ◽  
pp. 1125-1128 ◽  
Author(s):  
P. Proulx ◽  
C. K. Fung
Keyword(s):  
Sodium Lauryl Sulfate ◽  
Divalent Cations ◽  
Sodium Deoxycholate ◽  
Maximal Activity ◽  
Phospholipase A ◽  
Lauryl Sulfate ◽  
Alkaline Ph ◽  
Ph Optimum ◽  
E Coli

The hydrolysis of labelled phosphatidylethanolamine by E. coli was studied in vitro. Phospholipase A, as detected by 32P-labelled lysophosphatidylethanolamine formation, had two pH optima, 5 and 8.4. On the other hand lysophosphofipase was active only in the alkaline range, had a pH optimum of 10, and was inhibited by high concentrations of either sodium deoxycholate or sodium lauryl sulfate. Phospholipase A required Ca2+ addition for maximal activity at both pH optima. Mg2+ also stimulated the activity but other divalent cations tested were slightly inhibitory or without effect. Sodium lauryl sulfate completely inhibited at pH 5. Experiments with singly and doubly labelled phosphatidylethanolamine indicated that phospholipase A1 activity was predominant at both acid and alkaline pH. Lower levels of phospholipase A2 were detectable only at alkaline pH.

scholarly journals Phenotypic Analysis of Mice Lacking the Tmprss2-Encoded Protease

2006 ◽  
Vol 26 (3) ◽  
pp. 965-975 ◽  
Author(s):  
Tom S. Kim ◽  
Cynthia Heinlein ◽  
Robert C. Hackman ◽  
Peter S. Nelson
Keyword(s):  
Serine Protease ◽  
Serine Proteases ◽  
Biological Activities ◽  
Type Ii ◽  
Phenotypic Analysis ◽  
Normal Prostate ◽  
Prostate Hyperplasia ◽  
Transmembrane Serine Protease

ABSTRACT Tmprss2 encodes an androgen-regulated type II transmembrane serine protease (TTSP) expressed highly in normal prostate epithelium and has been implicated in prostate carcinogenesis. Although in vitro studies suggest protease-activated receptor 2 may be a substrate for TMPRSS2, the in vivo biological activities of TMPRSS2 remain unknown. We generated Tmprss2 −/− mice by disrupting the serine protease domain through homologous recombination. Compared to wild-type littermates, Tmprss2 −/− mice developed normally, survived to adulthood with no differences in protein levels of prostatic secretions, and exhibited no discernible abnormalities in organ histology or function. Loss of TMPRSS2 serine protease activity did not influence fertility, reduce survival, result in prostate hyperplasia or carcinoma, or alter prostatic luminal epithelial cell regrowth following castration and androgen replacement. Lack of an observable phenotype in Tmprss2 −/− mice was not due to transcriptional compensation by closely related Tmprss2 homologs. We conclude that the lack of a discernible phenotype in Tmprss2 −/− mice suggests functional redundancy involving one or more of the type II transmembrane serine protease family members or other serine proteases. Alternatively, TMPRSS2 may contribute a specialized but nonvital function that is apparent only in the context of stress, disease, or other systemic perturbation.

scholarly journals Reductions of copper ion-mediated low-density lipoprotein (LDL) oxidations of trypsin inhibitors, the sweet potato root major proteins, and LDL binding capacities

2020 ◽  
Vol 61 (1) ◽  
Author(s):  
Yeh-Lin Lu ◽  
Chia-Jung Lee ◽  
Shyr-Yi Lin ◽  
Wen-Chi Hou
Keyword(s):  
Sweet Potato ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Trypsin Inhibitors ◽  
Water Soluble ◽  
Affinity Column ◽  
Low Density ◽  
Native Page

Abstract Background The root major proteins of sweet potato trypsin inhibitors (SPTIs) or named sporamin, estimated for 60 to 80% water-soluble proteins, exhibited many biological activities. The human low-density lipoprotein (LDL) showed to form in vivo complex with endogenous oxidized alpha-1-antitrypsin. Little is known concerning the interactions between SPTIs and LDL in vitro. Results The thiobarbituric-acid-reactive-substance (TBARS) assays were used to monitor 0.1 mM Cu2+-mediated low-density lipoprotein (LDL) oxidations during 24-h reactions with or without SPTIs additions. The protein stains in native PAGE gels were used to identify the bindings between native or reduced forms of SPTIs or soybean TIs and LDL, or oxidized LDL (oxLDL). It was found that the SPTIs additions showed to reduce LDL oxidations in the first 6-h and then gradually decreased the capacities of anti-LDL oxidations. The protein stains in native PAGE gels showed more intense LDL bands in the presence of SPTIs, and 0.5-h and 1-h reached the highest one. The SPTIs also bound to the oxLDL, and low pH condition (pH 2.0) might break the interactions revealed by HPLC. The LDL or oxLDL adsorbed onto self-prepared SPTIs-affinity column and some components were eluted by 0.2 M KCl (pH 2.0). The native or reduced SPTIs or soybean TIs showed different binding capacities toward LDL and oxLDL in vitro. Conclusion The SPTIs might be useful in developing functional foods as antioxidant and nutrient supplements, and the physiological roles of SPTIs-LDL and SPTIs-oxLDL complex in vivo will investigate further using animal models.

scholarly journals PSVII-35 Late-Breaking Abstract: Microwave heat treatment feed effect on ruminal degradability and intestinal protein digestibility - a brief review

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 342-343
Author(s):  
Md Safiqur Rahaman Shishir ◽  
Muhammad Jamal Khan ◽  
Hassan Khanaki ◽  
Graham Brodie ◽  
Brendan Cullen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Protein Digestibility ◽  
Soya Bean ◽  
Canola Meal ◽  
Canola Seed ◽  
Intestinal Protein ◽  
Bean Meal ◽  
Ruminal Degradability ◽  
Soya Bean Meal

Abstract Rumen degradability of crude protein (CP) of feed is a major factor that determines the utilization of CP in ruminant production. This study briefly reviewed the findings from six international studies of microwave (MW) heat treatment effect on feed CP rumen degradability and intestinal CP digestibility. Six in vitro studies of concentrate feed (canola seed, canola meal, soya bean meal, cottonseed meal, corn, and barley) showed a decrease in effective rumen degradability of dry matter and protein by 4–40% and 17–40%, respectively compared to control group (untreated concentrate feed). Among the six studies, four studies identified the MW heat treatment effect on intestinal protein digestibility. Due to MW heat treatment, canola seed, canola meal, soya bean meal, and cottonseed meal showed an increase in intestinal CP digestibility by 17%, 20%, 21%, and 19%, respectively. Overall the briefly reviewed studies showed that, MW heat treatment substantially reduced feed CP ruminal degradability and increased in vitro CP digestibility of ruminally undegraded CP.

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