
Link:
Pharm/Biotech Resources
Title: Angiotensin converting enzyme homolog and uses
therefor
United States Patent: 6,884,771
Issued: April 26, 2005
Inventors: Acton; Susan (Lexington, MA); Robison; Keith E.
(Wilmington, MA); Hsieh; Frank Y. (Lexington, MA)
Assignee: Millennium Pharmaceuticals, Inc. (Cambridge, MA)
Appl. No.: 635501
Filed: August 9, 2000
Abstract
The present invention relates to the discovery of novel genes encoding an
angiotensin converting enzyme, Angiotensin Converting Enzyme-2 (ACE-2). The
invention provides therapeutics, prognostic and diagnostics methods for
treating blood pressure related disorders as well as various types of
allergic conditions, among others. Also disclosed are screening assays for
identifying compounds for treating and preventing these conditions.
Description of the Invention
BACKGROUND OF THE INVENTION
Hypertension, or high blood pressure, is the most common disease
affecting the heart and blood vessels. Statistics indicate that hypertension
occurs in more than 50 million Americans. The prevalence of hypertension
increases with age. Between 85 and 90% of cases are primary (i.e.,
essential) hypertension, i.e., a persistently elevated blood pressure that
cannot be attributed to any particular organic cause. The remaining
percentage of cases are secondary hypertension, i.e., elevated blood
pressure having an identifiable underlying cause such as kidney disease and
adrenal hypersecretion.
Hypertension is of considerable concern because of the harm it can do to the
heart, brain, and kidneys if it remains uncontrolled. The heart is most
commonly affected by high blood pressure. When blood pressure is high, the
heart uses more energy in pumping against the increased resistance caused by
the elevated arterial blood pressure. Because of the increased effort, the
heart muscle thickens and the heart becomes enlarged and needs more oxygen.
If it cannot meet the demands put on it, angina pectoris or even myocardial
infarction may develop. Hypertension can result in numerous complications
include left ventricular failure; atherosclerotic heart disease; retinal
hermorrhages, exudates, papilledema, and vascular accidents; cerebrovascular
insufficiency with or without stroke; and renal failure. An untreated
hypertensive patient is at great risk of developing disabling or fatal left
ventricular failure, myocardial infarction, cerebral hemorrhage or
infarction, or renal failure at early age. Hypertension is the most
important risk factor predisposing to stroke and is an important risk factor
predisposing to coronary atherosclerosis.
An abnormal blood pressure can also result from specific conditions or
diseases, such as heart failure. Heart failure is a chronic or acute state
that results when the heart is not capable of providing sufficient cardiac
output to satisfy the metabolic needs of the body. Heart failure is commonly
referred to as congestive heart failure (CHF), since symptoms of increased
venous pressure (pulmonary congestion with left heart failure and peripheral
edema with right heart failure) are often predominant. Symptoms and signs of
CHF include fatigue, peripheral and pulmonary edema, and visceral congestion
(e.g., dyspnea). These symptoms are produced by diminished blood flow to the
various tissues of the body and by accumulation of excess blood in the
various organs, that results from the heart being incapable of pumping out
the blood. Heart failure can result from several underlying diseases, most
commonly in industrialized nations from atherosclerotic coronary artery
disease with myocardial infarction. Myocardidis, various cardiomyopathies,
and valvular and congenital defects may also result in heart failure (Anderoli
et al., Cecil: Essentials of Medicine, Third Edition, WB Saunders Company,
1993). A major problem in CHF is the inability of the failing left ventricle
to maintain a normal blood pressure, thus resulting in increased pre- and
afterload, and leading to progressive ventricular dilation with wall
remodeling. Vasodilators which induce a reduction in pre- and afterload,
i.e., reduction of the systemic vascular resistance and reduction of the
peripheral vascular resistance, respectively, are currently used to treat
CHF (Lionel H. Opie, Drugs for the Heart, Third Edition, WB Saunders
Company, 1991).
One important system involved in regulating blood pressure is the
renin-angiotensin-aldosterone system. In this system, renin, a proteolytic
enzyme formed in the granules of the juxtaglomerular apparatus cells
catalyzes the conversion of angiotensinogen (a plasma protein) into
angiotensin I, a decapeptide. This inactive product is then cleaved by a
converting enzyme, termed angiotensin converting enzyme (ACE) mainly in the
lung, but also in the kidney and brain, to an octapeptide, angiotensin II,
which is a potent vasoconstrictor and also stimulates the release of
aldosterone. Aldosterone is an adrenal cortex hormone that promotes the
retention of salt and water by the kidneys and thus increases plasma volume,
resulting in an increase in blood pressure. Angiotensin II also stimulates
the release of norepinephrine from neural cells which interacts with
specific receptors on blood vessels, thereby resulting in an increase in
calcium and vasocontriction. Another mechanism by which angiotensin II
induces vasoconstriction is by interacting with specific receptors on blood
vessels, thereby resulting in an opening of calcium channels and an increase
in calcium, resulting in vasoconstriction.
ACE, also referred to as peptidyl dipeptidase A (EC 3.4.15.1) and kininase
II is a metallopeptidase, more particularly a zinc peptidase which
hydrolyses angiotensin I and other biologically active polypeptides, such as
kinins, e.g., bradykinin. Bradykinin is a vasodilator, which acts at least
in part by inducing release of vasodilator prostaglandins, and which is
inactivated upon hydrolysis by ACE. Thus, ACE increases blood pressure at
least in part by producing angiotensin II, a vasoconstrictor, and by
inactivating bradykinin, a vasodilator. Bradykinin is also involved in other
biological activities including mediation of pain and inflammatory
reactions.
The role of ACE in regulating blood pressure is further demonstrated at
least by the efficacy of ACE inhibitors in reducing hypertension and
treating CHF in individuals. ACE inhibitors have major roles as vasodilators
in hypertension and CHF and are among the most efficient drugs for treating
these disorders (see, e.g., Opie et al., Angiotensin Converting Enzyme
Inhibitors and Conventional Vasodilators, in Lionel H. Opie, Drugs for the
Heart, Third Edition, WB Saunders Company, 1991, p106). Several clinical
trials indicate that ACE inhibitors prolong survival in a broad spectrum of
patients with myocardial infarction and heart failure, ranging from those
who are asymptomatic with ventricular dysfunction to those who have
symptomatic heart failure but are normotensive and hemodynamically stable.
For example, one study demonstrated a 40% reduction in mortality at 6 months
in patients with severe heart failure (The CONSENSUS Trial Study Group, N.
Engl. J. Med. 316:1429 (1987); The CONSENSUS Trial Study Group, N. Engl. J.
Med. 325:293 (1991)).
ACE cleaves substrates other than angiotensin I and bradykinin. For example,
ACE cleaves enkephalins, as well as heptapeptide and octapeptide enkephalin
precursors. ACE also hydrolyzes the tridecapeptide neurotensin to a
dipeptide and undecapeptide (Skidgel et al. In Neuropeptides and Their
Peptidases, Ed. Turner A J, Chichester, UK, Ellis-Horwood, (1987)). ACE can
also cleave and thereby inactivate substance P (Skidgel et al., supra).
Several ACE inhibitors are currently available on the market (e.g.,
Captopril, Enalapril, Fosinopril, Lisinopril, and Ramipril). However, ACE
inhibitors in large doses can cause a variety of undesirable secondary
effects including nephrotic syndrome, membraneous glomerulonephritis,
nephritis, and leukopenia, as well as angioedema.
The isolation of novel nucleic acids encoding novel ACE proteins would be
useful, e.g., in developing drugs which are capable of regulating the
activity of ACE without having the negative secondary effects.
SUMMARY OF THE INVENTION
The present invention is based, at least in part, on the discovery of a
novel gene encoding a novel human protein, having sequence homologies with
known angiotensin converting enzymes (ACEs). Thus, the newly identified
proteins and nucleic acids described herein are referred to as "angiotensin
converting enzyme-2" or "ACE-2". The human ACE-2 gene transcript is shown in
FIG. 1 (SEQ ID NO:1) and includes 5′ and 3′ untranslated regions and a 2415
base pair open reading frame (SEQ ID NO:3) encoding an 805 amino acid
polypeptide having SEQ ID NO:2. The mature protein, i.e., the full length
protein without the signal sequence is comprised of about 787 amino acids.
ACE-2 is expressed predominantly in kidney and testis. A nucleic acid
comprising the cDNA encoding the full length human ACE-2 polypeptide has
been deposited at the American Type Culture Collection ([12301 Parklawn
Drive, Rockville, Md.] 10801 University Blvd., Manassas. Va. 20110-2209) on
Dec. 3, 1997 has been assigned ATCC Designation No. 209510.
An amino acid and nucleotide sequence analysis using the BLAST program (Altschul
et al. (1990) J. Mol. Biol. 215:403) revealed that certain portions of the
amino acid and nucleic acid sequences of the newly identified human ACE-2
protein and nucleic acid have a sequence similarity with certain regions of
angiotensin converting enzymes. In particular, the amino acid sequence of
the zinc binding domain, which is conserved in all ACE proteins identified
to date and which is located in the catalytic site of the enzyme and
necessary for catalytic activity, is also found in ACE-2. Amino acids which
have been identified as either contacting the zinc atom and/or involved in
the catalysis and are conserved among all ACE proteins, are present in
ACE-2. Thus, ACE-2 is believed to share at least some of the biological
activities of ACE proteins, in particular the peptidase activity. In fact,
as shown herein (see Example 5.4), ACE-2 cleaves the C-terminal amino acid
from angiotensin I to produce Ang (1-9). ACE-2 also comprises a
transmembrane domain which is present in most ACE proteins and which is
likely to mediate protein attachment to the cell membrane. Except for the
presence of other small regions of homology between ACE-2 and known ACE
proteins, the other portions of ACE-2 are significantly different from those
of known ACE proteins.
In one aspect, the invention features isolated ACE-2 nucleic acid molecules.
In one embodiment, the ACE-2 nucleic acid is from a vertebrate. In a
preferred embodiment, the ACE-2 nucleic acid is from a mammal, e.g. a human.
In an even more preferred embodiment, the nucleic acid has the nucleic acid
sequence set forth in SEQ ID NO:1 and/or 3 or a portion thereof. The
disclosed molecules can be non-coding, (e.g. a probe, antisense, or ribozyme
molecules) or can encode a functional ACE-2 polypeptide (e.g. a polypeptide
which specifically modulates biological activity, by acting as either an
agonist or antagonist of at least one bioactivity of the human ACE-2
polypeptide). In one embodiment, the nucleic acid molecules can hybridize to
the ACE-2 gene contained in ATCC designation No. 209510. In another
embodiment, the nucleic acids of the present invention can hybridize to a
vertebrate ACE-2 gene or to the complement of a vertebrate ACE-2 gene. In a
further embodiment, the claimed nucleic acid can hybridize with a nucleic
acid sequence shown in FIG. 1 (SEQ ID NOs: 1 and 3) or complement thereof.
In a preferred embodiment, the hybridization is conducted under mildly
stringent or stringent conditions.
In further embodiments, the nucleic acid molecule is an ACE-2 nucleic acid
that is at least about 70%, preferably about 80%, more preferably about 85%,
and even more preferably at least about 90% or 95% homologous to the nucleic
acid shown as SEQ ID NOs: 1 or 3 or to the complement of the nucleic acid
shown as SEQ ID NOs: 1 or 3. In a further embodiment, the nucleic acid
molecule is an ACE-2 nucleic acid that is at least about 70%, preferably at
least about 80%, more preferably at least about 85% and even more preferably
at least about 90% or 95% similar in sequence to the ACE-2 nucleic acid
contained in ATCC designation No. 209510 or shown set forth in SEQ ID NOs: 1
and/or 3 or complement thereof.
The invention also provides probes and primers comprising substantially
purified oligonucleotides, which correspond to a region of nucleotide
sequence which hybridizes to at least about 6 at least about 10, and at
least about 15, at least about 20, or preferably at least about 25
consecutive nucleotides of the sequence set forth as SEQ ID NO:1 or
complements of the sequence set forth as SEQ ID NO:1 or naturally occurring
mutants or allelic variants thereof, such as those described in the
Examples. In preferred embodiments, the probe/primer further includes a
label group attached thereto, which is capable of being detected.
For expression, the subject nucleic acids can be operably linked to a
transcriptional regulatory sequence, e.g., at least one of a transcriptional
promoter (e.g., for constitutive expression or inducible expression) or
transcriptional enhancer sequence. Such regulatory sequences in conjunction
with an ACE-2 nucleic acid molecule can provide a useful vector for gene
expression. This invention also describes host cells transfected with said
expression vector whether prokaryotic or eukaryotic and in vitro (e.g. cell
culture) and in vivo (e.g. transgenic) methods for producing ACE-2 proteins
by employing said expression vectors.
In another aspect, the invention features isolated ACE-2 polypeptides,
preferably substantially pure preparations, e.g. of plasma purified or
recombinantly produced polypeptides. The ACE-2 polypeptide can comprise a
full length protein or can comprise smaller fragments corresponding to one
or more particular motifs/domains, or fragments comprising at least about 5,
10, 25, 50, 75, 100, 125, 130, 135, 140 or 145 amino acids in length. In
particularly preferred embodiments, the subject polypeptide has an ACE-2
bioactivity, for example, it is capable of interacting with and/or
hydrolyzing a target peptide, such as angiotensin I, kinetensin, bradykinin
or neurotensin.
In a preferred embodiment, the polypeptide is encoded by a nucleic acid
which hybridizes with the nucleic acid sequence represented in SEQ ID NOs: 1
and 3. In a further preferred embodiment, the ACE-2 polypeptide is comprised
of the amino acid sequence set forth in SEQ ID NO:2. The subject ACE-2
protein also includes within its scope modified proteins, e.g. proteins
which are resistant to post-translational modification, for example, due to
mutations which alter modification sites (such as tyrosine, threonine,
serine or aspargine residues), or which prevent glycosylation of the
protein, or which prevent interaction of the protein with intracellular
proteins involved in signal transduction.
The ACE-2 polypeptides of the present invention can be glycosylated, or
conversely, by choice of the expression system or by modification of the
protein sequence to preclude glycosylation, reduced carbohydrate analogs can
also be provided. Glycosylated forms can be obtained based on derivatization
with glycosaminoglycan chains. Also, ACE-2 polypeptides can be generated
which lack an endogenous signal sequence (though this is typically cleaved
off even if present in the pro-form of the protein).
In yet another preferred embodiment, the invention features a purified or
recombinant polypeptide, which has the ability to modulate, e.g., mimic or
antagonize, an activity of a wild-type ACE-2 protein, e.g., its ability to
bind and/or hydrolyze angiotensin 1, kinetensin, bradykinin, or neurotensin,
or a peptide having a significant amino acid homology thereto. Preferably,
the polypeptide comprises an amino acid sequence identical or homologous to
a sequence designated in SEQ ID No: 2.
Another aspect of the invention features chimeric molecules (e.g., fusion
proteins) comprising an ACE-2 protein. For instance, the ACE-2 protein can
be provided as a recombinant fusion protein which includes a second
polypeptide portion, e.g., a second polypeptide having an amino acid
sequence unrelated (heterologous) to the ACE-2 polypeptide. A preferred
ACE-2 fusion protein is an immunoglobulin-ACE-2 fusion protein, in which an
immunoglobulin constant region is fused to an ACE-2 polypeptide.
Yet another aspect of the present invention concerns an immunogen comprising
an ACE-2 polypeptide in an immunogenic preparation, the immunogen being
capable of eliciting an immune response specific for an ACE-2 polypeptide;
e.g. a humoral response, an antibody response and/or cellular response. In a
preferred embodiment, the immunogen comprises an antigenic determinant, e.g.
a unique determinant of a protein encoded by the nucleic acid set forth in
SEQ ID NO:1 or 3; or as set forth in SEQ ID NO:2.
A still further aspect of the present invention features antibodies and
antibody preparations specifically reactive with an epitope of an ACE-2
protein.
The invention also features transgenic non-human animals which include (and
preferably express) a heterologous form of an ACE-2 gene described herein,
or which misexpress an endogenous ACE-2 gene (e.g., an animal in which
expression of one or more of the subject ACE-2 proteins is disrupted). Such
transgenic animals can serve as animal models for studying cellular and/or
tissue disorders comprising mutated or mis-expressed ACE-2 alleles or for
use in drug screening. Alternatively, such transgenic animals can be useful
for expressing recombinant ACE-2 polypeptides.
The invention further features assays and kits for determining whether an
individual's ACE-2 genes and/or proteins are defective or deficient (e.g in
activity and/or level), and/or for determining the identity of ACE-2
alleles. In one embodiment, the method comprises the step of determining the
level of ACE-2 protein, the level ACE-2 mRNA and/or the transcription rate
of an ACE-2 gene. In another preferred embodiment, the method comprises
detecting, in a tissue of the subject, the presence or absence of a genetic
alteration, which is characterized by at least one of the following: a
deletion of one or more nucleotides from a gene; an addition of one or more
nucleotides to the gene; a substitution of one or more nucleotides of the
gene; a gross chromosomal rearrangement of the gene; an alteration in the
level of a messenger RNA transcript of the gene; the presence of a non-wild
type splicing pattern of a messenger RNA transcript of the gene; and/or a
non-wild type level of the ACE-2 protein.
For example, detecting a genetic alteration or the presence of a specific
polymorphic region can include (i) providing a probe/primer comprised of an
oligonucleotide which hybridizes to a sense or antisense sequence of an
ACE-2 gene or naturally occurring mutants thereof, or 5′ or 3′ flanking
sequences naturally associated with the ACE-2 gene; (ii) contacting the
probe/primer with an appropriate nucleic acid containing sample; and (iii)
detecting, by hybridization of the probe/primer to the nucleic acid, the
presence or absence of the genetic alteration. Particularly preferred
embodiments comprise: 1) sequencing at least a portion of an ACE-2 gene, 2)
performing a single strand conformation polymorphism (SSCP) analysis to
detect differences in electrophoretic mobility between mutant and wild-type
nucleic acids; and 3) detecting or quantitating the level of an ACE-2
protein in an immunoassay using an antibody which is specifically
immunoreactive with a wild-type or mutated ACE-2 protein.
Information obtained using the diagnostic assays described herein (alone or
in conjunction with information on another genetic defect, which contributes
to the same disease) is useful for diagnosing or confirming that a
symptomatic subject (e.g. a subject symptomatic for hypertension,
hypotension, CHF, or a kinetensin-associated condition), has a genetic
defect (e.g. in an ACE-2 gene or in a gene that regulates the expression of
an ACE-2 gene), which causes or contributes to the particular disease or
disorder. Alternatively, the information (alone or in conjunction with
information on another genetic defect, which contributes to the same
disease) can be used prognostically for predicting whether a non-symptomatic
subject is likely to develop a disease or condition, which is caused by or
contributed to by an abnormal ACE-2 activity or protein level (e.g.
hypertension, hypotension, CHF, or a kinetensin-associated condition) in a
subject. In particular, the assays permit to ascertain an individual's
predilection to develop a condition associated with a mutation in ACE-2,
where the mutation is a single nucleotide polymorphism (SNP). Based on the
prognostic information, a doctor can recommend a regimen (e.g. diet or
exercise) or therapeutic protocol useful for preventing or prolonging onset
of the particular disease or condition in the individual.
In addition, knowledge of the particular alteration or alterations,
resulting in defective or deficient ACE-2 genes or proteins in an
individual, alone or in conjunction with information on other genetic
defects contributing to the same disease (the genetic profile of the
particular disease) allows customization of therapy for a particular disease
to the individual's genetic profile, the goal of "pharmacogenomics". For
example, an individual's ACE-2 genetic profile or the genetic profile of a
disease or condition, to which ACE-2 genetic alterations cause or
contribute, can enable a doctor: 1) to more effectively prescribe a drug
that will address the molecular basis of the disease or condition; and 2) to
better determine the appropriate dosage of a particular drug. For example,
the expression level of ACE-2 proteins, alone or in conjunction with the
expression level of other genes, known to contribute to the same disease,
can be measured in many patients at various stages of the disease to
generate a transcriptional or expression profile of the disease. Expression
patterns of individual patients can then be compared to the expression
profile of the disease to determine the appropriate drug and dose to
administer to the patient.
The ability to target populations expected to show the highest clinical
benefit, based on the ACE-2 or disease genetic profile, can enable: 1) the
repositioning of marketed drugs with disappointing market results; 2) the
rescue of drug candidates whose clinical development has been discontinued
as a result of safety or efficacy limitations, which are patient
subgroup-specific; and 3) an accelerated and less costly development for
drug candidates and more optimal drug labeling (e.g. since the use of ACE-2
as a marker is useful for optimizing effective dose).
In another aspect, the invention provides methods for identifying a compound
which modulates an ACE-2 activity, e.g. the interaction between an ACE-2
polypeptide and a target peptide, e.g., angiotensin I, a kinin, kinetensin
or neurotensin. In a preferred embodiment, the method includes the steps of
(a) forming a reaction mixture including: (i) an ACE-2 polypeptide, (ii) an
ACE-2 binding partner (e.g., a target peptide, such as angiotensin I or
kinetensin), and (iii) a test compound; and (b) detecting interaction of the
ACE-2 polypeptide and the ACE-2 binding protein. A statistically significant
change (potentiation or inhibition) in the interaction of the ACE-2
polypeptide and ACE-2 binding protein in the presence of the test compound,
relative to the interaction in the absence of the test compound, indicates a
potential agonist (mimetic or potentiator) or antagonist (inhibitor) of
ACE-2 bioactivity for the test compound. The reaction mixture can be a
cell-free protein preparation, e.g., a reconstituted protein mixture or a
cell lysate, or it can be a recombinant cell including a heterologous
nucleic acid recombinantly expressing the ACE-2 binding partner.
In preferred embodiments, the step of detecting interaction of the ACE-2 and
ACE-2 binding partner (e.g., angiotensin I or kinetensin) is a competitive
binding assay.
In preferred embodiments, at least one of the ACE-2 polypeptide and the
ACE-2 binding partner comprises a detectable label, and interaction of the
ACE-2 and ACE-2 binding partner is quantified by detecting the label in the
complex. The detectable label can be, e.g., a radioisotope, a fluorescent
compound, an enzyme, or an enzyme co-factor. In other embodiments, the
complex is detected by an immunoassay.
The invention also provides a methods for identifying an ACE-2 therapeutic,
comprising contacting in a reaction mixture an ACE-2 polypeptide, a target
peptide or analog thereof or portion thereof, and a test compound, in
conditions wherein, but for the presence of the test compound, the ACE-2
polypeptide cleaves one or more amino acids from the target peptide or
analog thereof or portion thereof to produce an ACE-2 target peptide
conversion product, and detecting the presence of at least one of the target
peptide or analog thereof or portion thereof, the ACE-2 target peptide
conversion product, and one or more amino acids. A preferred method for
determining the presence and/or the amount of at least one of the target
peptide or analog thereof or portion thereof, the ACE-2 target peptide
conversion product, and one or more amino acids comprises obtaining a mass
spectrum of the reaction mixture or of a part thereof.
Yet another exemplary embodiment provides an assay for screening test
compounds to identify agents which modulate the amount of ACE-2 produced by
a cell. In one embodiment, the screening assay comprises contacting a cell
transfected with a reporter gene operably linked to an ACE-2 promoter with a
test compound and determining the level of expression of the reporter gene.
The reporter gene can encode, e.g., a gene product that gives rise to a
detectable signal such as: color, fluorescence, luminescence, cell
viability, relief of a cell nutritional requirement, cell growth, and drug
resistance. For example, the reporter gene can encode a gene product
selected from the group consisting of chloramphenicol acetyl transferase,
luciferase, beta-galactosidase and alkaline phosphatase.
Also within the scope of the invention are methods for treating diseases or
disorders which are associated with an aberrant ACE-2 level or activity or
which can benefit from modulation of the activity or level of ACE-2, in
particular diseases or conditions which are improved by modulation of the
level of one or more angiotensin I conversion products, e.g., by an increase
or decrease in the production of Ang.(1-9), Ang.(1-5), and/or Ang.(1-8) (angiotensin
II); conditions that are improved by modulation of kinetensin or kinetensin
(1-8) level; conditions that are improved by modulation of bradykinin (1-8)
or bradykinin (1-7); or conditions that are improved by modulation of
neurotensin (1-13) or neurotensin (1-12). Thus, the invention provides
methods for treating hypertension, CHF, inflammatory reactions, allergic
reactions, and methods to reduce pain. The methods comprise administering,
e.g., either locally or systemically to a subject, a pharmaceutically
effective amount of a composition comprising an ACE-2 therapeutic. Depending
on the condition, the therapeutic can be an ACE-2 agonist or an ACE-2
antagonist. For example, an ACE-2 antagonist therapeutic can be administered
to a subject having hypertension or CHF. In another embodiment, an ACE
agonist is administered locally to a subject to reduce the inflammation and
pain resulting from an insect sting or bite, which was accompanied by an
injection of bradykinin.
In a particular embodiment of the invention, an ACE-2 antagonist is
administered to a subject alone or together with an ACE antagonist. Thus, a
dual therapy comprising administering to a subject an antagonist of ACE-2
and an antagonist of ACE can be used to prevent the accumulation of
angiotensin II, e.g., to thereby reduce the blood pressure of the subject
and prevent the development or appearance of conditions related thereto.
The invention also provides methods for identifying other potential
substrates of an ACE-2 polypeptide as well as the product of the enzymatic
reaction. In a preferred embodiment, the method comprises contacting a
preparation containing an ACE-2 polypeptide with a test compound, e.g., a
peptide, for a time sufficient for the enzymatic reaction to occur, and
subjecting the reaction mixture, or a portion thereof, to mass spectrometry.
The comparison of the mass spectra of the test compound with that of the
reaction mixture after incubation to allow the enzymatic reaction to occur,
will indicate whether the test compound was converted into a new compound,
in which case the test compound is a substrate of the ACE-2 polypeptide.
Claim 1 of 25 Claims
1. An isolated polypeptide comprising an amino acid sequence which is at
least 90% identical to the amino acid sequence set forth in SEQ ID NO:2.
____________________________________________
If you want to learn more
about this patent, please go directly to the U.S.
Patent and Trademark Office Web site to access the full
patent.