CA1183527A

CA1183527A - Antigenic peptide compound

Info

Publication number: CA1183527A
Application number: CA000386008A
Authority: CA
Inventors: Erwin Goldberg
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-09-16
Filing date: 1981-09-16
Publication date: 1985-03-05

Abstract

ANTIGENIC PEPTIDE COMPOUND

ABSTRACT

The novel antigenic peptide compound of this invention comprises a sequence of seven amino acids, namely, methionine-glutamine-lysine-aspartic acid-leucine-glutamic acid-leucine, all of the amino acids being in their L-forms. The compound has utility in vaccines for reducing the fertility of mammals.

Description

~335~:7 BACXGROUN~ AND PRIOR ART

Mammalian spermatozoa have been kn~n to be antigenic or many years. Moxe recently, it has been demonstrate~ that mammalian sperm co~tain an antigenic enz~meJ which is known as the C4 isozyme of lactate dehydrogenase (LD~-X, LDH C4 ) . LDH-C4 h~s been isolated . .
- in pure crystalline f~rm xom mouse testes. Goldberg .(1972) J. Biol. ChemO 247:2~44-2048. The enzyme has a molecular weight of 140,000 and is composed of four id~ntical C
subunits. The amino acid se~ue~ce and ~hree-dimensional structure of LDH-C4 has been studied and partia~ly detexmined by a n~mber of investigators. See Musick et al ~1976) ~ Mol.
Biol. 104:659-668; and Wheat et al (1977~ Bîochem. ~ Bioph~s.
Res. Comm., 74, No. 3:1066-1077. h~eat et al determined the sequence of the e;sential thiol peptide ~rom amino acid 159 to 171, and found this to be nearly identical to essential thiol peptides from other vertebrate LDE i~oz~mes.

- I~ 1974 r Dr. ~rwin Goldberg reviewed ~he ef~ects o~
immunization with LD~-X ~LDH-C4) on fertili~y, and advanced the possibility that l'by using a defined macromolecular constituent of sperm it becomes possible to elucidate its primary structure in terms of amino acid se~uence r to map specifically the antigenic determinan.t (s) responsible for induci~g infertility, and then to construct sy~the~ic pep~ides containing these determinants. Possessing ~he capability for synthesi~ing a molecule with such properties, makes the immunological approach to fertility control feasible. ~r Karolinska Symposia on Research Methods in Reproductive ~ndocrinology, 7th Symposia: Immunological Approaches to Fertility Control, Geneva, 1974 202L222.

~83~5Z7 However r such synthetic antigenic peptides remained a goal and not an achievement although their theoretical desir-ability had been recognized. In 1979, Dr. Erwin Goldberg summarized the state of the art as follows:

"In conclusion, and on a practical basis immunotherapy for birth control requires more than effectiveness, specificity, reversibility, and absence of systemic side reaction. Rather large amounts of the antigen must be available in unequivocally pure form. This condition probably cannot be met by a natural product enzyme antigen from sperm or testes. Rather, contraceptive technology requires a synthe-sizable peptide fragment retaining anti-genicity and provoking a response which impairs fertility. Completion of the struct-ural analysis of LDH-C4 should allow mapping of antigenic determinants and synthesis of such peptides for use in a new contraceptive technology," "Recent Advances in ReProduction and Regulation of Fertilityli' G.P. Talwar, editor, Elsevier/North Holland ~iomedical Press (1979).

SUMMARY OF INVENTION

It has now been discovered that an antigenic peptide can be prepared by synthesizing a linear sequence of seven amino acids comprising: methionine-glutamine-lysine-aspartic acid-leucine-glutamic acid-leucine. All of the amino acids used to prepare the foregoing peptide are in their L-form.
30 The N-terminal is methionine and the C-terminal is leucine.
Although not known with certainty, it is believed that the foregoing sequence of seven amino acids corresponds to amino acids 325 to 332 of LDH-C4. This is contrary to a recently published tentative sequence. See Musick et al (1979) J. Biol. Chem., 254, No. 16:7621-7623~

DESCRIPTION OF INVENTION

The present invention relates to a novel antigenic linear peptide having a chain length of seven amino acids.

35;~
The formula of this peptide can be represented as follows:

N-Met~Gln-Lys-Asp-Leu-~lu-Leu-C

In the foregoing formula, the letter "N" designates the N-terminal amin~ acid, while the letter "C" designates the C-terminal amino acid. Met, Gln, Lys, Asp, Glu, and 1eu represent the L-amlno acid forms, respectively, of methionine, glutamine, lysine, aspartic acid, glutamic acid, :: and leucine.

The peptide compound of the present inve~tion can be 10 synthesized from its constituent amino acids. For example, the synthesis can be carried out by the Merrifield solid phase method, as described in J.A.C.S. 85:2149-2154 ~1963). This solid phase method for synthesizing se~uences of amin~ acids is also described in Stewart and Young, ~
(W. H. Freeman and Co~, San Francisco, 1969), pages 1-4. In this procedure, the C-terminal amino acid, such as leuci~e for the compound of this in-~ention, is attache~ to chloromethylated polystyrene divinylbenzene copolymer beads.
Each subsequent amino acid, with suitab-le protecting group, is then added sequentially to the srowing chain. For exam~le, as described in the Merrifield article, the protective group may be a carbobenzoxy group. By the procedure of coupling, deprotection, and coupling of the next amino acid, the desired amino acid sequence and chain length can be produced. ~s a final step, the protective ~roup is removed from the ~terminal amino acid (YiZ. methionine), and the C-terminal amino acid is cleaved from the resin, using a suitable reagent, such as trifluoroacetic acid and hydroyen bromide. Sinca this syn-thesis procedure is well known, it is not believed that it will be necessary to further describe it herein~ The peptide of this invention can be prepared by this sy~thesis procedure for use in reducing the fertility of mammals.

~33~2~

To utilize the antigenic peptide of this invention in ~he form o~ a ~ertility reducing vaccine, the peptide is coniugated to a carrier molecule, which is preferably a protein which itself elicits an antigenic response and which can be safely administered. For example, the peptide can be coupled to tetanus toxoid for administr~tion by intra-muscular injection. ~or example, a mixture of l~Mole tetanus .. toxoid, 60yNoles antigenic ~eptide, and lB millimoles l-ethyl-3-(3 dimethyl aminopropyl~ carbodiimide hydrochloride reacted in water (pH6) for 12 houxs at room temperature an~
24 hours at 4 gives a product containing 3~5 moles o~
~eptide/mole tetanus toxoid. Excess reactants can be removed by dialysis or gel ~iltration. See Pique et al, Immunoche _ st~, 15:55-60 (1978~. Alterna~ively, the peptide may be coupled using bisdiazotized benzidine ~B~ssiri et al, ndocrinology, 90:722 (1972)] or glutaraldehyde.

~ or intramuscular injection, the coupled peptide may be suspended in a sterile isotonic saline solution, or other conventional vehicle, and, if desired, an adjuvant may be included. A preferred use of such a vaccine is for administra-tion to human ~emales. Anti~odies will be formed, which will appear in the oviduct ~luids and thereby achieve a significant reduction in fertility. For this purpose, the amount to be administered will range from about 1 to 10 milligrams ~mg) of the antigenic peptide.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. The method of preparing a vaccine for reducing the fertility of female mammals, comprising conjugating to an antigenic carrier protein the antigenic linear peptide compound having the formula: N-Met-Gln-Lys-Asp-Leu-Glu-Leu-C
wherein N-Met is N-terminal L-Methionine, Leu-C is C-terminal L-leucine, and Gly, Lys, Asp, Glu, and Leu are the L-amino acid forms, respectively, of glutamine, lysine, aspartic acid, glutamic acid, and leucine; and suspending the conjugated protein-peptide in an injectable vehicle.