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The Plethora of Angiotensin-Converting Enzyme-Processed Peptides in Mouse Plasma.

ABSTRACT: Angiotensin-converting enzyme (ACE) converts angiotensin I into the potent vasoconstrictor angiotensin II, which regulates blood pressure. However, ACE activity is also essential for other physiological functions, presumably through processing of peptides unrelated to angiotensin. The goal of this study was to identify novel natural substrates and products of ACE through a series of mass-spectrometric experiments. This included comparing the ACE-treated and untreated plasma peptidomes of ACE-knockout (KO) mice, validation with select synthetic peptides, and a quantitative in vivo study of ACE substrates in mice with distinct genetic ACE backgrounds. In total, 244 natural peptides were identified ex vivo as possible substrates or products of ACE, demonstrating high promiscuity of the enzyme. ACE prefers to cleave substrates with Phe or Leu at the C-terminal P2' position and Gly in the P6 position. Pro in P1' and Iso in P1 are typical residues in peptides that ACE does not cleave. Several of the novel ACE substrates are known to have biological activities, including a fragment of complement C3, the spasmogenic C3f, which was processed by ACE ex vivo and in vitro. Analyses with N-domain-inactive (NKO) ACE allowed clarification of domain selectivity toward substrates. The in vivo ACE-substrate concentrations in WT, transgenic ACE-KO, NKO, and CKO mice correspond well with the in vitro observations in that higher levels of the ACE substrates were observed when the processing domain was knocked out. This study highlights the vast extent of ACE promiscuity and provides a valuable platform for further investigations of ACE functionality.

SUBMITTER: Semis M

PROVIDER: S-EPMC6693507 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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The Plethora of Angiotensin-Converting Enzyme-Processed Peptides in Mouse Plasma.

Semis Margarita M Gugiu Gabriel B GB Bernstein Ellen A EA Bernstein Kenneth E KE Kalkum Markus M

Analytical chemistry 20190507 10

Angiotensin-converting enzyme (ACE) converts angiotensin I into the potent vasoconstrictor angiotensin II, which regulates blood pressure. However, ACE activity is also essential for other physiological functions, presumably through processing of peptides unrelated to angiotensin. The goal of this study was to identify novel natural substrates and products of ACE through a series of mass-spectrometric experiments. This included comparing the ACE-treated and untreated plasma peptidomes of ACE-kno ...[more]

PMID: 31021607

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Project description:Angiotensin converting enzyme (ACE) is known for converting inactive angiotensin I into the potent vasoconstrictor angiotensin II, playing a critical role in blood pressure regulation. However, there is evidence that the dicarboxypeptidase activity of ACE is also essential for other physiological processes likely through processing of various peptide substrates. This study used mass spectrometry for the comprehensive detection and identification of natural substrates and products of ACE within the mouse plasma peptidome. The plasma peptidome of ACE KO mice was obtained through a multi-step purification process which included organic TCA precipitation as well as size exclusion and reversed phase chromatography. The obtained complex mixture of endogenous peptides was then subjected to in vitro cleavage by ACE. ACE-treated and untreated samples were then analyzed by LC/MS on an Orbitrap mass spectrometer, followed by alignment of MS1 data by Progenesis QI software. The MS1 signals that gained or lost intensity after treatment with ACE, were considered as possible products and substrates of ACE, respectively, and were selected for a targeted MS/MS analysis, and subsequently identified with PEAKS 8.5 and Proteome Discoverer software. Results. Close to 250 natural peptides were identified as possible substrates and products of ACE, demonstrating the high promiscuity of the enzyme. The use of internal standards as well as detection of some expected endogenous peptides, such as angiotensin II and bradykinin, supported the validity of the approach. Some of the newly identified substrates of ACE are known for their biological activities. For example, a fragment of complement C3, the 17-amino acid peptide C3f, exhibits spasminogenic activity and was processed by ACE. ACE cleavage of select peptides was further confirmed in vitro. Also, concentrations of ACE substrates in plasma from mice with variant genetic ACE domain backgrounds were determined by LC/MS using multiple reaction monitoring on a triple quadrupole mass spectrometer. The in vivo results were consistent with the in vitro results, in the sense that higher levels of the ACE substrates were observed when the respective processing domain was knocked out. The use of transgenic mice as well as ACE with single active domain allowed clarifying the ACE domain selectivity towards individual peptide substrates. This study resulted in creation of a library of substrates and products of ACE that can be further tested for their biological function and can help to elucidate the link between ACE and the numerous physiological effects attributed to its activity.

Dataset Information

The Plethora of Angiotensin-Converting Enzyme-Processed Peptides in Mouse Plasma.

Publications

The Plethora of Angiotensin-Converting Enzyme-Processed Peptides in Mouse Plasma.

Similar Datasets

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