ABSTRACT
ACE2, the first known human homologue of angiotensin-converting enzyme (ACE), was identified from 5' sequencing of a human heart failure ventricle cDNA library. ACE2 has an apparent signal peptide, a single metalloprotease active site, and a transmembrane domain. The metalloprotease catalytic domains of ACE2 and ACE are 42% identical, and comparison of the genomic structures indicates that the two genes arose through duplication. In contrast to the more ubiquitous ACE, ACE2 transcripts are found only in heart, kidney, and testis of 23 human tissues examined. Immunohistochemistry shows ACE2 protein predominantly in the endothelium of coronary and intrarenal vessels and in renal tubular epithelium. Active ACE2 enzyme is secreted from transfected cells by cleavage N-terminal to the transmembrane domain. Recombinant ACE2 hydrolyzes the carboxy terminal leucine from angiotensin I to generate angiotensin 1-9, which is converted to smaller angiotensin peptides by ACE in vitro and by cardiomyocytes in culture. ACE2 can also cleave des-Arg bradykinin and neurotensin but not bradykinin or 15 other vasoactive and hormonal peptides tested. ACE2 is not inhibited by lisinopril or captopril. The organ- and cell-specific expression of ACE2 and its unique cleavage of key vasoactive peptides suggest an essential role for ACE2 in the local renin-angiotensin system of the heart and kidney. The full text of this article is available at http://www. circresaha.org.
Subject(s)
Angiotensin I/metabolism , Carboxypeptidases/genetics , Kidney/enzymology , Myocardium/enzymology , Renin-Angiotensin System , Adult , Amino Acid Sequence , Angiotensin-Converting Enzyme 2 , Angiotensin-Converting Enzyme Inhibitors/pharmacology , Animals , Base Sequence , CHO Cells , Carboxypeptidases/chemistry , Carboxypeptidases/metabolism , Cardiomyopathy, Dilated/enzymology , Cells, Cultured , Cricetinae , Culture Media, Serum-Free , Female , Gene Duplication , Gene Expression Regulation, Enzymologic , Gene Library , Genetic Vectors , Heart Ventricles/enzymology , Humans , Lisinopril/pharmacology , Male , Mass Spectrometry , Molecular Sequence Data , Myocardium/cytology , Peptidyl-Dipeptidase A/genetics , Sequence Alignment , Sequence Homology, Amino Acid , Substrate Specificity , Testis/enzymology , TransfectionABSTRACT
The high resolution of capillary zone electrophoresis/mass spectrometry (CZE/MS) offers a promising technique to characterize biomolecules in pharmaceutical and biotechnology industries. A novel capillary zone electrophoresis/electrospray ionization time-of-flight mass spectrometry (CZE/ESI-TOFMS) interface was designed in this study to successfully integrate ESI-TOFMS, nanospray, and CZE for biomolecular identification. The interface offers a novel way to take advantage of the high resolution separation achieved during CZE and the detection sensitivity of nanospray ESI-MS. The results showed mixtures of peptides were highly resolved within a few minutes (each CZE electropherogram of a peptide is 2-3 seconds). The novel CZE/ESI-TOFMS interface may simultaneously provide sensitivity, data acquisition speed, mass range, and mass resolution while maintaining resolution of the CZE separation.
