JPH0339518B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides novel peptides (human hormones),
More specifically, it relates to human PHI (PHM) derivatives. In this specification, when amino acids, peptides, protecting groups, active groups, etc. are indicated by abbreviations, they shall comply with the regulations of IUPAC and IUB or the common symbols in the field, and examples thereof are listed below.
Furthermore, when optical isomers are possible for amino acids, etc., the D-form, L-form, or racemic form is indicated unless otherwise specified. Ser; serine Leu; leucine Gly; glycine Gln; glutamine Glu; glutamic acid Lys; lysine Tyr; tyrosine Ala; alanine Met; methionine Tos; p-toluenesulfonyl group Boc; tertiary butoxycarbonyl group ONP; p-nitrophenoxy group Bzl; Benzyl group OBzl; benzyloxy group Cl ₂ -Bzl; 2,6-dichlorobenzyl group Cl-Z; 2-chlorobenzyloxycarbonyl group Recent advances in research on peptide hormones have revealed that many of the peptide hormones present in the gastrointestinal tract It has been found that many hormones found in the brain are also found in the gastrointestinal tract, and these hormones are linked to brain-intestinal peptides (Brain-intestinal peptides).
Research on these hormones has been in the spotlight as neuroendocrinology. The present inventors also discovered that VIP (vasoactive intestinal tract), which belongs to the glucagon-secretin family,
polypeptide) [Mutt, V. & said, SI, Eur.J.
Biochem. 42 , 581-589 (1974)] and PHI
(Tatemoto, K. & Mutt, V., Proc. Natl.
Acad.Sci., USA., Vol.78, No.11, 6603−6607
(1981)], and in particular human-derived ones, and in the process, we discovered that the human neuroblastoma cell line NB-OK-
(Yanaihara, N. et al, Biomedical Research,
2(6), 728-734 (1981)], the precursor prehormone (prepro-VIP) of human VIP [Obata, K. et al.
FEBS Letters 136, 123-126 (1981)] was successfully isolated, its c-DNA was cloned, and the base sequence of the acid was determined. As a result, they discovered that prepro-VIP contained a novel amino acid sequence in addition to human VIP, and that it was human gastrointestinal peptide hormone (human PHI).
We succeeded in chemically synthesizing PHI and completed the present invention. That is, the present invention provides a peptide represented by the formula H-Leu-Leu-Gly-Gln-Leu-Ser-Ala-Lys-Lys-Tyr-Leu-Glu-Ser-Leu-Met-NH ₂ (1) and a salt thereof. Related. The peptide of the present invention represented by formula (1) is a derivative of human gastrointestinal hormone [human PHI (PHM)],
Based on the hormonal action (physiological action) as a PHI, it has, for example, blood flow increasing action, insulin and prolactin secretion increasing action, smooth muscle contracting action, etc., such as blood flow improving agents, antidiabetic drugs, hormone preparations, prolactinoma It is useful as a diagnostic agent, etc., and also as an immunizing antigen for producing human PHI antibodies. The peptide of the present invention represented by formula (1) of the present invention is
It can be easily synthesized by simple operations using easily available commercially available amino acids. The chemical synthesis method for the peptide of the present invention will be described in detail below. The peptide of the present invention can be synthesized using a conventional peptide synthesis method, specifically, "The Peptides" No. 1.
Volume (1966) [Schroder and Luhke,
Academic press, New York, USA] or “Peptide Synthesis” [Izumiya et al., Maruzen Co., Ltd. (1975
For example, the azide method, chloride method, acid anhydride method, mixed acid anhydride method, DCC method, active ester method (p-nitrophenyl ester method, N-hydroxysuccinimide ester method) method, cyanomethyl ester method, etc.), method using Woodward's reagent K, carbodiimidazole method, redox method, DCC/additive (HONB, HOBt, HOSu) method, etc. In the above method, both a solid phase method and a liquid phase synthesis method can be applied. The peptide of the present invention is usually synthesized according to the general polypeptide synthesis method described above, for example, by the so-called stepwise method in which amino acids are sequentially condensed one by one to the terminal amino acid, or by a method in which the amino acids are coupled into several fragments. Manufactured. More specifically, when employing a solid phase synthesis method, for example, a C-terminated amino acid is bound to an insoluble carrier via its carboxyl group, and then the amino protecting group is removed, and then the amino acid represented by formula (1) is synthesized. It is produced by sequentially bonding amino group-protected amino acids according to the sequence through a condensation reaction with their reactive amino groups and reactive carboxyl groups, synthesizing the peptide step by step, and after synthesizing the entire sequence, removing the peptide from the insoluble carrier. Ru. The insoluble carrier used here may be any of a variety of carriers that have the ability to bond with a reactive carboxyl group, but it is preferable to use a carrier that provides an amide upon elimination, such as a benzhydrylamine resin. Also, depending on the N-terminal amino acid,
It can also be synthesized in the same manner by binding to a common insoluble carrier that has the ability to bind to the amino group.
In this case and when using the liquid phase method, the C-terminal amino acid, i.e., Met, can be determined according to the conventional method by the method of Quitt et al. [P. Quitt et al. Helb. Chim. Acta. 46 , 327
(1963)] as methionine amide. In any of the above methods, Tyr, Glu, Lys
It is preferable that the side chain functional group of each amino acid of and ser is protected, and this is protected by a conventional protecting group, and the protecting group is removed after the reaction is completed.
Furthermore, the functional groups involved in the reaction are usually activated. Each of these reaction methods is well known, and the reagents used therein are also appropriately selected from known methods. Examples of protecting groups for amino groups include benzyloxycarbonyl, Boc, tert-amyloxycarbonyl, isobornyloxycarbonyl, p-methoxybenzyloxycarbonyl, Cl-Z, adamantyloxycarbonyl, trifluoroacetyl, phthalyl, formyl, Examples include o-nitrophenylsulfenyl and diphenylphosphinothioyl groups. Examples of protecting groups for the hydroxyl group of Ser include Bzl,
Examples include tert-butyl, acetyl, and tetrahydropyranyl groups. As a protecting group for the hydroxyl group of Tyr, for example, Bzl,
Examples include Cl ₂ -Bzl, benzyloxycarbonyl, acetyl, and Tos group. Examples of protecting groups for the amino group of Lys include benzyloxycarbonyl, Cl-Z, Cl2 _- Bzl,
Examples include Boc and Tos groups. The carboxyl group of Glu can be protected by, for example, benzyl alcohol, methanol, ethanol, tert-
This is carried out by esterification using butanol or the like. Examples of activated carboxyl groups include:
For example, the corresponding acid chlorides, acid anhydrides or mixed acid anhydrides, azides, active esters (pentachlorophenol, p-nitrophenol, N-hydroxysuccinimide, N-hydroxybenztriazole, N-hydroxy-5-norbornene-
esters with 2,3-dicarboximide, etc.), and the like. The peptide bond forming reaction may be carried out in the presence of a condensing agent such as a carbodiimide reagent such as dicyclohexylcarbodiimide or carbodiimidazole, or tetraethylpyrophosphine. Hereinafter, the production of the peptide of the present invention will be specifically explained using a reaction scheme. [Reaction scheme-1] A-Met-OH (a) ↓ A-Met-R ¹ (b) ↓ H-Met-R ¹ (c) ↓A-Leu-OH (d) A-Leu-Met- R ¹ (E) ↓↓↓ A−Len−Leu−Gly−Gln−Leu−Ser −Ala−Lys−Lys−Tyr−Leu−Glu −Ser−Leu−Met−R ¹ (F) ↓ H−Leu− Leu-Gly-Gln-Leu-Ser -Ala-Lys-Lys-Tyr-Leu-Glu -Ser-Leu-Met-NH ₂ (1) [In the formula, A is a protecting group for an amino group and R ¹ is an insoluble carrier. show. ] In the above, preferable A is
Boc, benzyloxycarbonyl group, p-methoxybenzyloxycarbonyl group, etc., and preferred examples of R ¹ include benzhydrylamine resin. In addition, in each reaction, if the amino acid used has a side chain functional group that does not participate in the reaction, it is protected by the above-mentioned protecting group as usual, and this is removed at the same time as the insoluble carrier R ¹ is removed. . In the above method, the reaction between the amino acid (a) (or its carboxyl group activated) and the insoluble carrier R ¹ is carried out using the reactive carboxyl group of the amino acid (a) according to a conventional method. This is done by combining it with ¹ . For example, when a benzhydrylamine resin is used in the reaction, various known solvents commonly used in peptide condensation reactions,
For example, the reaction is carried out in the presence of anhydrous dimethylformamide, dimethyl sulfoxide, pyridine, chloroform, dioxane, dichloromethane, tetrahydrofuran, ethyl acetate, N-methylpyrrolidone, hexamethylphosphoric triamide, or a mixed solvent thereof. In addition, the reaction may be carried out, if necessary, by
Reagents used in normal peptide bond formation reactions,
For example, N,N-dicyclohexylcarbodiimide (DCC), N-ethyl-N'-dimethylaminocarbodiimide, 1-ethyl-3-diisopropylaminocarbodiimide, 1-cyclohexyl-3-
It can also be carried out in the presence of a dehydration condensation agent such as carbodiimides such as (2-morpholinyl-4-ethyl)carbodiimide. Insoluble carrier and amino acids (a)
Although there is no particular limitation on the ratio of the latter to the former, it is generally preferable to use an excess amount of the latter, generally about 1 to 3 equivalents. There is no particular limitation on the amount of the dehydration condensing agent used, and it is usually preferable to use it in an equimolar amount to the amino acid (a). The reaction temperature is within the usual range used for peptide bond-forming reactions, generally about -
The temperature is appropriately selected from the range of 40°C to about 60°C, preferably about -20°C to about 40°C. Reaction time is generally several minutes ~
It is said to take about 30 hours. The elimination reaction of the protecting group A of the immobilized amino acid of the general formula (b) thus obtained is carried out by a conventional method.
Examples of such methods include hydrogenation using a catalyst such as palladium or palladium black, reductive methods such as reduction with metallic sodium in liquid ammonia, trifluoroacetic acid, hydrochloric acid, hydrogen fluoride, methanesulfonic acid, and hydrobromic acid. Examples include acidolysis using strong acids such as. Hydrogenation using the above catalyst can be carried out, for example, at a hydrogen pressure of 1 atmosphere and at a temperature of 0 to 40°C. The amount of catalyst used is usually 100 mg to 1
The reaction is generally completed in about 1 to 48 hours. The acidolysis is carried out without a solvent, usually at about 0 to 30°C, preferably about 0 to 20°C, for about 15 minutes to 1 hour. The amount of acid used is usually about 5 to 10 times the amount of the raw material compound. When only the protecting group A is removed in the acidolysis, it is preferable to use trifluoroacetic acid or hydrochloric acid as the acid. Further, the above reduction with metallic sodium in liquid ammonia can be carried out using an amount of metallic sodium such that the reaction solution is colored permanent blue for about 30 seconds to 10 minutes, usually at about -40°C to -70°C. . The reaction between the resulting solid-phase amino acid of general formula (c) and the amino acid (d) (or its carboxyl group activated) is usually carried out in an equimolar amount to 10 times the molar amount of the latter to that of the former. , preferably in equimolar amounts ~
The reaction is carried out in the same manner as the reaction between the amino acid (a) and the insoluble carrier described above, using a 5-fold molar ratio. The thus obtained peptide of general formula (e) is converted into A-Ser-OH, A-Ser-OH, A-Ser-OH, A-
Glu-OH, A-Leu-OH, A-Thr-OH, A
-Lys-OH, A-Lys-OH, A-Ala-OH, A
-Ser-OH, A-Leu-OH, A-Gln-OH, A
-Gly-OH, A-Leu-OH, A-Leu-OH amino acids or those with protected side chain functional groups or those with activated carboxyl groups are sequentially condensed to form the general formula (H). ) can be derived from the peptide represented by The condensation reaction and the elimination reaction of the protecting group A are carried out in the same manner as described above. In addition, the obtained peptide (F) can be derived into the peptide (1) of the present invention by removing the protecting group A, removing the protecting group of the side chain functional group of the amino acid, and removing the insoluble carrier R ¹ in the same manner. Ru. Here, the elimination reaction of the protective group for the side chain functional group and the insoluble carrier R ¹ can be carried out in the same manner as the elimination reaction of the protective group A. In this case, it is preferable to use hydrogen fluoride or hydrobromic acid as the acid.
In addition, each amino acid used in the above method is
Any known commercially available products may be used. The peptide of the present invention of formula (1) produced as described above is purified from the reaction mixture by means of peptide separation, such as extraction, partitioning, column chromatography, etc. The peptide represented by the formula (1) of the present invention can be easily synthesized by using easily available commercially available amino acids by using a carrier, and can be used as an immunizing antigen or a hapten thereof. human
Antibodies having specific reactivity to PHI (PHM) can be obtained. The antibodies can be produced in humans by, for example, binding them to a carrier for affinity chromatography and using them in the chromatography.
It can be used for the purification of PHI, and the human PHI
It can be used as an antibody in various immunoassays,
It can be used for quantifying human PHI and diagnosing various diseases. The above immunoassay method, such as radioimmunoassay (RIA) method or enzyme immunoassay (EIA)
In the method, the peptide of the present invention can also be used in this method.
Radioactive substances such as ¹²⁵ I and ¹³¹ I, peroxidase (POX), chymotrybusinogen, procarboxypeptidase, glyceraldehyde-3-phosphate dehydrogenase, amylase, phosphorylase, D
-Nase, P-Nase, β-galactosidase, glucose-6-phosphatate dehydrogenase, ornithine decarboxylase, and other various enzyme reagents can be introduced and used as labeled antigens.
The introduction of the above-mentioned radioactive substance can be carried out by a conventional method, such as the oxidative iodination method using chloramine T [WM
Hunter and F.C. Greenwood; Nature, 194 ;
495 (1962), BiochemJ, 89 , 144, (1963)]
The introduction of the enzyme reagent is carried out using a conventional coupling method such as Erlanger (BF
Erlanger et al.'s method [Acta.Endocrinol.Suppl.,
168, 206 (1972)] and the method of MH Karol et al. [Proc. Natl, Acad. Sci., USA., 57 , 713
(1967)]. Furthermore, the peptide of the present invention can be used as an immunizing antigen by adsorbing it onto a polymer such as polyvinylpyrrolidone or charcoal powder. When the peptide of the present invention is used as a hapten, it is reacted with a suitable carrier in the presence of a hapten-carrier binding reagent to form an immunizing antigen. As the carrier, a wide range of high-molecular natural or synthetic proteins commonly used in the preparation of antigens can be used. Examples of the carrier include animal serum albumins such as horse serum albumin, bovine serum albumin, rabbit serum albumin, human serum albumin, and sheep serum albumin; horse serum globulin;
Animal serum globulin such as bovine serum globulin, rabbit serum globulin, human serum globulin, ovine serum globulin; animal thyroglobulin such as equine thyroglobulin, bovine thyroglobulin, rabbit thyroglobulin, human thyroglobulin, ovine thyroglobulin; Horse hemoglobulin, bovine hemoglobulin, rabbit hemoglobulin, human hemoglobulin,
Animal hemoglobulins such as ovine hemoglobulin; keyhole limpet hemocyanin (KLH)
Hemocyanins of animals such as
Publication, J. Immun., 111 , 260-268 (1973), J.
Immun., 122 , 302-308 (1979), J.Immun., 98 ,
893-900 (1967) and Am.J.Physiol., 199 , 575-
578 (1960) or further purified versions of these); polylysine, polyglutamic acid,
Examples include lysine-glutamic acid copolymers, copolymers containing lysine or ornithine, and the like. As the hapten-carrier binding reagent, a wide variety of those commonly used for preparing antigens can be used. Specifically, tyrosine, histidine, and tryptophan are cross-linked, such as bisdiazotized benzidine (BDB) and bisdiazotized benzidine (BDB).
Diazonium compounds such as 3,3'-dianisidine (BDD); aliphatic dialdehydes such as glyoxal, malondialdehyde, glutaraldehyde, succinaldehyde, and adipaldehyde that crosslink amino groups; ;Crosslinking between thiol groups, such as dimaleimide compounds such as N,N'-o-phenylene dimaleimide and N,N'-m-phenylene dimaleimide;Crosslinking between amino groups and thiol groups for example metamaleimidobenzoyl-N-hydroxysuccinimide ester, 4
Maleimidocarboxyl-N-hydroxysuccinimide esters such as -(maleimidomethyl)-cyclohexane-1-carboxyl-N'-hydroxysuccinimide ester; reagent used in the usual peptide bond-forming reaction to form an amide bond between an amino group and a carboxyl group. , for example N, N-
Dicyclohexylcarbodiimide, N-ethyl-
N'-dimethylaminocarbodiimide, 1-ethyl-3-diisopropylaminocarbodiimide,
1-cyclohexyl-3-(2-morpholinyl-
Examples include dehydration condensation agents such as carbodiimides such as 4-ethyl)carebodiimide. As the hapten-carrier binding reagent, a combination of a diazonium arylcarboxylic acid such as p-diazonium phenylacetic acid and a conventional peptide bond forming reaction reagent, such as the dehydration condensation agent described above, can also be used. The above antigen production reaction can be carried out, for example, in an aqueous solution or
The reaction is usually carried out in a normal buffer solution having a pH of 7 to 10 at 0 to 40°C, preferably around room temperature, for about 1 to 24 hours. Through the above process, a desired antigen consisting of a peptide-carrier complex in which a carrier and a hapten are bound is obtained through the mediation of a hapten-carrier binding reagent. The antigen obtained after completion of the reaction can be easily isolated and purified by conventional methods such as dialysis, gel filtration, and fractional precipitation. A method for producing antibodies reactive with human PHI using the antigen obtained as described above or the peptide of the present invention as an immunizing antigen is described, for example, in the literature by Yanaihara et al. [Gastroenterology, 72, 803-810 (1977)]. The method can be followed. For example, the above-mentioned antibody is produced by administering an antigen to a mammal, causing the desired antibody to be produced in vivo, and collecting the antibody. There are no particular restrictions on the mammal used for antibody production, but rabbits, goats, guinea pigs, etc. are usually preferably used. For antibody production, dilute a predetermined amount of antigen with physiological saline to an appropriate concentration and add Freund's auxiliary solution (Complete
Freund's Adjuvant) to prepare a suspension, which may be administered to mammals for immunization. Antibodies are collected by collecting blood from an immunized animal, centrifuging it, and separating the serum. The peptide of the present invention thus obtained can form a salt with a pharmacologically acceptable acidic or basic compound. Examples of such acidic compounds include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and hydrobromic acid; organic acids such as fumaric acid, maleic acid, acetic acid, oxalic acid, malic acid, and citric acid; and basic compounds such as Examples include sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium hydrogen carbonate, and the like. When the peptide of the present invention and its salts are used as a blood flow improving agent, for example, they are usually processed into a crude form together with a pharmaceutical carrier, but it is particularly preferable to process them into an injection form. When prepared as an injectable solution, the resulting formulation is preferably sterile and isotonic with blood. When forming into an injection, any diluent commonly used in this field can be used. For example, water, physiological saline, etc. can be mentioned. In this case, a sufficient amount of common salt or glycerin to prepare an isotonic solution may be included in the preparation in the form of an injection. In addition, the above-mentioned preparations may contain conventional buffering agents, soothing agents, preservatives, etc., as well as coloring agents, preservatives, fragrances, flavors, sweeteners, etc., and other pharmaceuticals, if necessary. Furthermore, the above-mentioned active ingredients are dissolved in distilled water for injection at the time of use, and can also be used as a solubilizing agent. The preparation prepared as described above can be administered in a manner depending on its form. In the case of an injection, it is administered intravenously alone or mixed with a normal replacement fluid such as an amino acid. The dosage of the active ingredient is determined appropriately depending on the purpose of use, symptoms, etc., but it is usually 1 ng to 1 ng per person per day.
It is preferable to use it in the range of about mg/Kg, and 1
Preferably, it is administered in divided doses 2 to 4 times a day. Below, in order to explain the present invention in more detail, general formula
Production examples and test examples of the peptide of the present invention represented by (1) will be given below, but the present invention is not limited thereto. In addition, in each production example, each amino acid shows the L form. Further, the Rf value was measured by thin layer chromatography on silica gel using the following mixed solvent. Rf ¹ ...n-butanol-acetic acid-water (4:1:5) ^Rf2 ...n-butanol-acetic acid-pyridine-water (15:3:10:12) Production example 1 Boc-Met-OH in 25 ml of methylene chloride 897mg of
6.00 g of benzhydrylamine resin (0.4 mmol NH ₂ /g resin: Protein Research Foundation) was added, and the mixture was allowed to react at room temperature for 120 minutes. Soak the resin in 25 ml of methylene chloride for 1.5 minutes.
Boc-Met-
Get resin. The Boc-Met resin obtained above is added to 25 ml of a methylene chloride solution of 1% ethanediol and 25% trifluoroacetic acid (TFA) and reacted for 30 minutes at room temperature. The resin was treated with 25 ml of methylene chloride 6 times, 10 times.
% triethylamine in methylene chloride solution 25ml
3 times for 1.5 minutes, then 1.5 minutes with 25 ml of methylene chloride.
The H-Met-resin is obtained by washing 6 times for 6 minutes each. Add the above H-Met-resin to 25 ml of a solution of 900 mg of Boc-Leu-OH dissolved in methylene chloride,
Next, 7.2 mg of a solution of 743 mg of DCC dissolved in methylene chloride is added and reacted at room temperature for 2 hours. After washing the resin 6 times with 25 mg of tyrene chloride for 1.5 minutes,
Add 900 mg of Boc-Leu-OH and 486 mg of 1-hydroxybenzotriazole to a solution of 10 mg of dimethylformamide and 15 mg of methylene chloride, then add 7.2 ml of a solution of 743 mg of DCC dissolved in methylene chloride, and react in the same manner again. (double coupling method). The resin is thoroughly washed with methylene chloride to obtain Boc-Len-Met-resin. In the same manner as above, Boc-Leu-Met-resin is de-Boc-reacted, and then the following amino acids are sequentially subjected to condensation and de-Boc reaction. Boc−Ser(Bzl)−OH 1062mg Boc−Glu(Bzl)−OH 1214mg Boc−Leu−OH 900mg Boc−Tyr(Cl ₂ −Bzl)−OH 1649mg Boc−Lys(Cl−Z)−OH・(tert− Butylammonium salt; TBA) 1754mg Boc−Lys(Cl−Z)−OH・TBA 1754mg Boc−Ala−OH 681mg Boc−Ser(Bzl)−OH 1062mg Boc−Leu−OH 900mg Boc−Gln−OH 886mg Boc−Gly −OH 630mg Boc−Leu−OH 900mg Boc−Leu−OH 900mg Thus H−Leu−Leu−Gly−Gln−Leu−
Ser(Bzl)−Ala−Lys(Cl−Z)−Lys(Cl−Z)−
Tyr( _Cl2 −Bzl)−Leu−Glu(Bzl)−Ser(Bzl)−
Leu-Met-resin is obtained. Of this, 3.27 g was dissolved in 40 ml of hydrogen fluoride containing 4 ml of anisole and 0.75 ml of methyl ethyl sulfide, and after incubation at 0°C for 60 minutes, excess hydrogen fluoride was distilled off under reduced pressure to remove the residue. After washing three times with ethyl acetate, 3M acetic acid
Extract with 100ml and freeze-dry to obtain 950mg of crude product. 500 mg of this was gel-filtered using Cephadex G-25 (Flumacia, column 2.4 x 145 cm, eluent 1M acetic acid), and then droplet countercurrent distribution (φ3 x 400 mm)
tube
−Gly−Gln−Leu−Ser−Ala−Lys−Lys−Tyr
Obtain 137 mg of -Leu-Glu-Ser-Leu-Met- _NH2 . This peptide is hereinafter referred to as "peptide A." Rf value: Rf ¹ = 0.22 Rf ² = 0.62 HPLC: ODS-120T (0.46 x 25 cm; Toyo Sodasha),
0.01N HCl/CH ₃ CN = 75/25 to 55/45 gradient, flow rate: 1 ml/min, retention time: 12 minutes Amino acid analysis value: 6N HCl, 24-hour hydrolysis at 110°C, amino acid automatic analyzer model 835 (Hitachi) )
Analysis Ser 1.82(2) Glu 1.92(2) Gly 0.97(1) Ala 0.96(1) Met 1.04(1) Leu 5.08(5) Tyr 1.07(1) Lys 2.15(2) Test example Peptide A blood flow The increasing effect was tested [Gasroenterology, 72, 803-810 (1977)]. That is, the abdomen of an adult mongrel dog is opened under anesthesia, the root of the superior mesenteric artery is removed from the surrounding connective tissue, and an electromagnetic flowmeter probe is attached. After the minute blood flow has stabilized, add 10 ^-10 mol of peptide A in physiological saline to
Kg was injected intravenously, and changes in blood flow were measured. As a result, a strong increase in blood flow was observed.

Claims (1)

[Claims] 1. A peptide represented by the formula H-Leu-Leu-Gly-Gln-Leu-Ser-Ala-Lys-Lys-Tyr-Leu-Glu Ser-Leu-Met-NH ₂ and salts thereof.