The Enzymatic Degradation of Angiotensin II Analogues by proteolytic enzyme in vitro

1972 ◽  
Vol 50 (2) ◽  
pp. 113-118 ◽  
Author(s):  
M. C. Carrara ◽  
D. Regoli ◽  
W. K. Park
Keyword(s):  
Amino Acids ◽  
Angiotensin Ii ◽  
Unnatural Amino Acids ◽  
Enzymatic Degradation ◽  
Leucine Aminopeptidase ◽  
Receptor Interaction ◽  
Angiotensin I ◽  
Peptide Receptor ◽  
Angiotensin Ii Analogues

Angiotensin II (ATII), angiotensin I (ATI), and Acpc analogues of ATII, 8-Achc-ATII, 8-D-Phe-ATII, and 8-Ala-ATII, were incubated in vitro with carboxypeptidase, chymotrypsin, and leucine-aminopeptidase in order to study the influence of unnatural amino acids (Acpc, Achc, and D-Phe) and of L-Ala on the activity of peptidases.Fragments occurring during the breakdown of peptides were demonstrated by paper chromatography in an ascending system.ATII and ATI are rapidly inactivated by carboxypeptidase and chymotrypsin, while the degradation by leucine-aminopeptidase is slower.Substitution of L-Phe with Acpc, Achc, D-Phe, or L-Ala in position 8 prevents the degradation by carboxypeptidase. Chymotrypsin degrades 3-Acpc-ATII and 5-Acpc-ATII but not 4-Acpc-ATII. The action of leucine-aminopeptidase is not influenced by substituting Acpc to each one of the first five amino acids composing the molecule of angiotensin.The possible implications of these findings for the peptide-receptor interaction is discussed.

In vitro degradation of angiotensin II (A-II) by human placental subcellular fractions, pregnancy sera and purified placental aminopeptidases

1985 ◽  
Vol 110 (1) ◽  
pp. 135-139 ◽  
Author(s):  
Shigehiko Mizutani ◽  
Haruyuki Akiyama ◽  
Osamu Kurauchi ◽  
Hiroyuki Taira ◽  
Osamu Narita ◽  
...  
Keyword(s):  
Amino Acids ◽  
Angiotensin Ii ◽  
High Performance ◽  
Leucine Aminopeptidase ◽  
Soluble Fraction ◽  
In Vitro Degradation ◽  
Aminopeptidase A ◽  
Aminopeptidase P ◽  
Soluble Fractions

Abstract. The degradation of angiotensin II (Asp1-Arg2-Val3-Tyr4-Ile5-His6-Pro7-Phe8: A-II) by human placental particulate and soluble fractions, pregnant and non-pregnant sera, and highly purified placental enzymes such as placental leucine aminopeptidase P-LAP (microsomal), retroplacental serum P-LAP (soluble), aminopeptidase A and post-proline endopeptidase, was studied by measuring liberated amino acids by high performance liquid chromatography. Placental particulate and soluble fractions degraded A-II almost completely into single amino acids. The purified P-LAP (microsomal) actively liberated five amino acids from the N-terminal. The placental particulate fraction containing P-LAP (microsomal) also actively liberated these amino acids. The purified aminopeptidase A liberated Asp1 very actively as expected. When the ratio of the velocity of liberation of each amino acid to P-LAP activity measured with leu-p-nitroanilide as a substrate was calculated, placental soluble fraction liberated Asp1 very actively, but the liberation rate of Asp1 with the purified P-LAP (soluble) was very low. Therefore it seems that the enzyme in the placental soluble fraction and pregnancy serum responsible for the Asp1 liberation is not P-LAP (soluble), but aminopeptidase A. The mixture of purified P-LAP (soluble) and aminopeptidase A showed higher liberation rate of Arg2 and Val3 than that with purified aminopeptidase A alone, demonstrating that once the N-terminal Asp1 was liberated, the P-LAP (soluble) attacks the shorter peptide (angiotension III) very actively. It was concluded that P-LAP (microsomal) together with aminopeptidase A seem to contribute greatly to the degradation of A-II in pregnant women.

Engineering an acetyllysine reader with photocrosslinking amino acid for interactome profiling

2021 ◽  
Author(s):  
Babu Sudhamalla ◽  
Anirban Roy ◽  
Soumen Barman ◽  
Jyotirmayee Padhan
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Protein Interactions ◽  
Unnatural Amino Acids ◽  
Protein Protein Interactions ◽  
Site Specific ◽  
Powerful Approach

The site-specific installation of light-activable crosslinker unnatural amino acids offers a powerful approach to trap transient protein-protein interactions both in vitro and in vivo. Herein, we engineer a bromodomain to...

Measurement of Plasma Renin Activity as a Valid Estimation of Plasma Angiotensin Status

1978 ◽  
Vol 15 (1-6) ◽  
pp. 250-252 ◽  
Author(s):  
J. E. Roulston ◽  
G. A. Macgregor ◽  
Theresa Adam ◽  
Nirmala D. Markandu
Keyword(s):  
Angiotensin Ii ◽  
Plasma Renin Activity ◽  
Plasma Renin ◽  
Renin Activity ◽  
Activity Measurement ◽  
Plasma Samples ◽  
Angiotensin I ◽  
Plasma Angiotensin ◽  
Rate Limiting

Measurement of plasma renin activity is widely used as an indirect assessment of plasma angiotensin II concentration. There has been some controversy over the validity of this assay as an estimate of circulating angiotensin II levels because, during the in vitro generation of angiotensin I by renin, over a period of time, substrate concentration may diminish to such an extent that it becomes rate-limiting, giving an artificially low reflection of angiotensin II levels. In this paper the initial angiotensin I concentration, that is the concentration before in vitro angiotensin I generation, has been compared with the corresponding plasma renin activity for 2752 individual plasma samples. A linear relationship was found between the initial angiotensin I concentration and the plasma renin activity below 60 ng ml−1 h−1. This indicates that, under the conditions of this assay, substrate does not appear to become rate-limiting except at exceedingly high levels of plasma renin activity. These results appear to provide further validation for the use of plasma renin activity measurement as a reflection of the concentration of circulating angiotensin II levels.

Presence of Angiotensin Peptides in Human Urine

1992 ◽  
Vol 38 (9) ◽  
pp. 1768-1772 ◽  
Author(s):  
K Hermann ◽  
R Rittweger ◽  
M I Phillips ◽  
J Ring
Keyword(s):  
Circadian Rhythm ◽  
Angiotensin Ii ◽  
Human Urine ◽  
Food Additives ◽  
Angiotensin I ◽  
In Vitro Degradation ◽  
Angiotensin Peptides ◽  
Daily Excretion ◽  
Anaphylactoid Reactions

Abstract Immunoreactive angiotensin I and angiotensin II were found in human urine that was purified on octadecasilylsilica cartridges. The daily excretion of angiotensin I and II in healthy volunteers was 189.00 (SE 38.36) and 17.54 (SE 3.07) pmol/24 h or 148.09 (SE 32.22) and 12.82 (SE 2.34) pmol/L, respectively (n = 12). No circadian rhythm was observed in the excretion patterns of angiotensin I and II. In vitro degradation of angiotensin I or II could not be detected in acidified urine samples. A marked increase in the excretion of angiotensin I and II could be demonstrated in patients with anaphylactoid reactions to drugs and food additives after oral challenge. Immunoreactive angiotensin I and II could be characterized by HPLC as Ile5-angiotensin I, Ile5-angiotensin II, and angiotensin II metabolites.

Synthesis and in vitro antitumor activity of new octapeptide analogs of somatostatin containing unnatural amino acids

Amino Acids ◽  
2015 ◽  
Vol 47 (5) ◽  
pp. 1007-1013 ◽  
Author(s):  
Svetlana Ts. Staykova ◽  
Diana W. Wesselinova ◽  
Lyubomir T. Vezenkov ◽  
Emilia D. Naydenova
Keyword(s):  
Amino Acids ◽  
Antitumor Activity ◽  
Unnatural Amino Acids

scholarly journals Development of improved tRNAs for in vitro biosynthesis of proteins containing unnatural amino acids

1996 ◽  
Vol 3 (12) ◽  
pp. 1033-1038 ◽  
Author(s):  
Sharon T. Cload ◽  
David R. Liu ◽  
Wayne A. Froland ◽  
Peter G. Schultz
Keyword(s):  
Amino Acids ◽  
Unnatural Amino Acids ◽  
In Vitro Biosynthesis

scholarly journals The participation of methionine and cysteine in the formation of bonds resistant to the action of proteolytic enzymes in heated casein

1975 ◽  
Vol 34 (2) ◽  
pp. 163-173 ◽  
Author(s):  
Danuta Pieniaźek ◽  
Maria Rakowska ◽  
Hanna Kunachowicz
Keyword(s):  
Amino Acids ◽  
Leucine Aminopeptidase ◽  
Proteolytic Enzymes ◽  
Cysteic Acid ◽  
Enzymic Hydrolysis ◽  
Rat Growth ◽  
Cysteine Content ◽  
Amino Acid Contents ◽  
Formation Of Complexes

1. The influence of temperature, moisture content and the presence of glucose on the level of available methionine and cysteine in casein was studied.2. Differences between total and available methionine and cysteine contents of heated casein (90° for 24 h) were determined by an in vitro method. The maximum losses in total and available methionine content were 22 and 51% respectively. The losses in total and available cysteine content were 24 and 100% respectively.3. The results indicated that for heated casein the release of amino acids by proteolytic enzymes was less complete than for native casein.4. The results of rat growth assays suggested that diets containing oxidized casein are less well utilized by rats than those containing native casein. The decrease in body-weight of rats receiving the diets containing oxidized casein could be counteracted by the addition of methionine and 20 g unoxidized casein/kg diet.5. There was a lower level of some available amino acids (determined after enzymic hydrolysis using pancreatopeptidase E (EC 3.4.4.7), leucine aminopeptidase (EC 3.4.1.1) and prolidase (EC 3.4.3.7)), including those essential for the rat, in oxidized casein as compared with native casein.6. Cysteic acid, in oxidized casein, probably makes impossible the utilization of the amino acids in its neighbourhood.7. From the differences in the available amino acid contents of the native, oxidized and heated casein it was concluded that the oxidation of casein causes the formation of complexes in the polypeptide chain, resistant to enzymic hydrolysis, but to a much lesser extent than does heating.

125I-LABELLING OF ANGIOTENSIN I AND II

1971 ◽  
Vol 67 (1) ◽  
pp. 104-116 ◽  
Author(s):  
Meta Damkjær Nielsen ◽  
Mogens Jørgensen ◽  
Jørn Giese
Keyword(s):  
Angiotensin Ii ◽  
Paper Chromatography ◽  
Enzymatic Degradation ◽  
Specific Activity ◽  
Simple Procedure ◽  
Enzymatic Conversion ◽  
Purification Step ◽  
Angiotensin I ◽  
Low Concentrations ◽  
Chloramine T

ABSTRACT A simple procedure for a reproducible preparation of radioiodinated angiotensin analogues is described. The iodination is performed at a low level of radioactivity – 200 μCi per 10 μg peptide – with low concentrations of chloramine-T and sodium metabisulphite. No destruction of the peptide occurs during the iodination. The yield is high, and the only purification step needed is a separation of iodinated peptide from non-labelled peptide. This separation is performed by means of column chromatography on DEAE-Sephadex A 25. The specific activity of labelled angiotensin I or II prepared by this method was about 500 μCi/μg. The homogeneity of the radioiodinated angiotensin analogues was established by means of paper chromatography and enzymatic degradation studies, including experiments on the enzymatic conversion of 125I-angiotensin I to 125I-angiotensin II. Radiochromatograms obtained after storage for various periods showed perfect stability of the labelled compounds. Immunological characteristics, as evaluated by standard displacement curves with selected antisera and maximal binding to excess antibody, were reproducible from batch to batch.

In vitro study on the effects of bradykinin potentiating factor and angiotensin II analogue on degradation and conversion of angiotensin I and II in plasma

1974 ◽  
Vol 52 (3) ◽  
pp. 287-292 ◽  
Author(s):  
Ogihara Toshio ◽  
Yamamoto Toshihide ◽  
Doi Kei ◽  
Kumahara Yuichi ◽  
Kimura Terutoshi ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
In Vitro Study ◽  
Vitro Study ◽  
Angiotensin I
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