A Peptide Which Regulates Weight Gain In Mammals

The present invention as conceived and/or reduced to practice under and/or in conjunction with U.S. Government Grant No. GM 27695 from the National Institutes of Health (NIH) and the U.S. Government may have certain rights in the invention.

Technical Field

The present invention relates to a peptide which regulates weight gain in mammals.

Background Art

Appetite-suppressant agents are known, largely those which are based upon or derived from amphetamine. In fact, amphetamine is the parent compound of all but one of the agents currently used for appetite-suppression. Due to the potential for abuse that many of these drugs present, however, the use of such agents in reducing weight is controversial-, among physicians. That the use of amphetamine and similar appetite-suppressant agents is controversial may be seen from the fact that these compounds are now under the control of the Bureau of Narcotics and Dangerous Drugs (BNDD) . Amphetamine, methamphetamine and phenmetrazine are in BNDD Schedule II which is highly restrictive, whereas the others are in Schedules III and IV which are succeedingly less restrictive, but still indicative of abuse potential.

Worst yet, even when these drugs are used to reduce weight, tolerance develops over a period of a few to several

weeks. However, the mood elevation may be retained with steadily increasing doses, leading to psychological and physical dependency. The massive doses required to support severe dependency finally lead to irreversible peripheral and central nervous system damage.

Thus, it would be extremely desirable to obtain substances for regulating weight gain in mammals which avoid the disadvantages described above.

Disclosure of the Invention

Accordingly, it is object of the present invention to provide a peptide which regulates weight gain in mammals.

It is also an object of the present invention to provide pharmaceutical compositions which contain the peptide of the present invention.

Accordingly, the above objects and others which will become apparent in view of the following disclosure, are provided by a peptide having the formula:

aβ-yδeη θλμπpσ

wherein at least six of the amino acid residues are as defined in the sequential positions specified in the sequence:

CHHRKKGYADLY

wherein C is cysteine, H is histidine, R is arginine, K is lysine, G is glycine, Y is tyrosine, A is alanine, D is aspartic acid and L is leucine; and the remaining amino acids are each independently glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine, lysine, hydroxylysine, histidine, arginine, phenylalanine, tyrosine, tryptophan, proline or hydroxyproline.

Brief Description of the Drawings

Figure 1 illustrates the weights of rabbits before injection with the peptide of the present invention and at the end of 5 months.

Figure 2 illustrates average weight gain for groups of mice receiving either the peptide of the present invention or another comparative peptide.

Figures 3 and 4 illustrate the delay in weight gain for mice treated with the peptide of the present invention as compared to a comparative control group.

Figure 5 illustrates the absence of a delay in weight gain for a group of mice treated with a saline control.

Best Mode for Carrying Out the Invention

In accordance with the present invention, a peptide is provided which is capable of regulating weight gain in mammals.

In accordance with the present invention, a peptide of the following formula is provided:

aβyδeη θXμπpσ

wherein at least six of the amino acid residues are as defined in the sequential positions specified in the sequence:

CHHRKKGYADLY

wherein C is cysteine, H is histidine, R is arginine, K is lysine, G is glycine, Y is tyrosine, A is alanine, D is aspartic acid and L is leucine; and the remaining amino acids are each independently glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine, lysine, hydroxylysine, histidine, arginine, phenylalanine, tyrosine, tryptophan, proline or hydroxyproline.

Notably, for the generic description of the present peptide, letters of the Greek alphabet are used.

However, the peptide sequences of the present invention are defined relative to the peptide of the formula:

CHHRKKGYADLY

wherein the standard one-letter amino acid abbreviation is used, for example, whereby C is cysteine, H is histidine, R is arginine, K is lysine, G is glycine, Y is tyrosine, A is alanine, D is aspartic acid and L is leucine.

In the present specification, the letters of the Greek alphabet and the standard one-letter amino acid abbreviation is used. See, for example, Organic Chemistry of Biological Compounds, R. Barker at pp. 55-56 (Prentice Hall, 1971) .

Thus, of interest are dodecapeptides having at least six of the specific residues described immediately above in their designated positions in the sequence CHHRKKGYAKLY.

For example, peptides of the following formula are noted:

ctβyδeη θλμπpσ

wherein

is cysteine; β is histidine; γ is histidine; δ is arginine; e is lysine; η is lysine; and

θ , λ, μ, π, p, and σ are each independently glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine, lysine, hydroxylysine, histidine, arginine, phenylalanine, tyrosine, tryptophan, proline or hydroxyproline.

Further, peptides of the following formula are noted:

aβyδeη θXμπpσ

θ is glycine; λ is tyrosine; μ is alanine; π is aspartic acid; p is leucine; σ is tyrosine; and

°-ι β/ Υι & _r ε _r and η are each independently glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine, lysine, hydroxylysine, histidine, arginine, phenylalanine, tyrosine, tryptophan, proline or h droxyproline.

Moreover, peptides of the following formula are noted:

βyδeη θλμπpσ

δ is arginine; e is lysine; η is lysine; θ is glycine; λ is tyrosine; μ is alanine; and

°-r β _r It i P and σ are each independently glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine, lysine, hydroxylysine, histidine, arginine,

phenylalanine, tyrosine, tryptophan, proline or hydroxyproline.

Thus, specifically contemplated is the peptide:

βyδ eη θλμnpσ

wherein at least six of the amino acid residues are as defined and in the sequential position specified in the sequence:

CHHRKKGYADLY

wherein C is cysteine, H is histidine, R is arginine, K is lysine, G is glycine, Y is tyrosine, A is alanine, D is aspartic acid, and L is leucine; and the remaining amino acid residues are each independently glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine lysine, hydroxy lysine, histidine, arginine, phenylalanine, tyrosine, tryptophan, proline of hydroxy proline.

For example, the present peptide may have the formulae:

C-H-7-e-7j-G-Y-A-D-p-σ, or α-H-7-R- e-K-0 -Y-jLi-D- -Y ,

In each of the above formulae, the Greek letters indicate amino acid residues as broadly defined above, i.e., any one of glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine, lysine, hydroxy lysine, histidine, arginine, phenylalanine, tyrosine, tryptophan, proline or hydroxy proline; whereas the standard one-letter amino acid abbreviations are used for the remaining amino acid residues.

However, it is more preferred if at least seven of the amino acid residues of the sequence:

ctβyδeη θλμπpσ

are as defined and in the sequential position specified in the sequence:

CHHRKKGYADLY

wherein C is cysteine, H is histidine, R is arginine, K is lysine, G is glycine, Y is tyrosine, A is alanine, D is aspartic acid, and L is leucine, and the remaining three amino acid residues are each independently glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine, lysine, hydroxy lysine, histidine, arginine,

phenylalanine, tyrosine, tryptophan, proline or hydroxyproline.

Examples of peptides having at least seven of the specified amino acids are those having the formulae:

C-j3-H-S-K-77-G-λ-A-7r-L-Y, or

C-H-γ-S-K-K-G-λ-A-π-L-σ, o—r C-/3-H- δ -K-η-G-λ-A-D-p-Y, or

C-H-H-R-e-η-G-Y-A-ij-p-σ, or

.C-H-γ-cS-e-Tj-G-Y-A-D-L-σ, or

C-H-γ-S-e-77-G-Y-A-D-L-σ, or

C-H-γ-S-K-K-ø-7-μ-D-L-Y, or C-H-H-5-K-7?-θ-Y-A-77-L-σ.

It is even more preferred if at least eight, nine, ten or eleven of the amino acid residues of the sequence:

aβyδ eη θλμπpσ

are as defined and in the sequential position specified in the sequence:

CHHRKKGYADLY

which is defined as above.

Examples of peptides having at least eight of the specified amino acids are those having the formula:

C-/3 -H-S-K-77-G-λ-A-D-L-Y, or C-H-γ-R-G-17-ø-Y-A-D-L-Y, or C-β-γ-£-K-K-G-λ-A-D-L-Y, or C-H-H-£-e-K-0-λ-A-D-L-Y, or C-H-H-R-K-77 -G-Y-A-π- -σ , or C-H-H- δ- e -K-K-λ-A-D-L-σ , or C-H-γ-R-K- η-θ - Y-A-π-L-σ .

Examples of peptides having at least nine of the specified amino acids are these having the formulae:

C-H-H-R-K-η-G-Y-A-D-p-σ, or

C-H-γ-R-e-K-G-λ-A-D-p-Y, or

C-H-H-5-K-K-G-λ-μ-D-L-Y, or

C-H-γ-R-K-K-G-Y-μ-D-p-Y, or

C-H-H-R-K-f-0-Y-A-7r-L-Y, or C-H-H-£-e-K-G-λ-A-D-L-Y, or

C-H-H-R-K-K-G-Y-A-π-p-σ.

Examples of peptides having at least ten of the specified amino acids are those having the formula:

α-H-H-R-K-K-G-Y-A-D-L-α, or α-/3-H-R-K-K-G-Y-A-D-L-Y, or

C-/3-γ-R-K-K-G-Y-A-D-L-Y, or C-H-H-R-K-K-G-Y-A-D-L-σ, or C-H-H~S-e-K-G-Y-A-D-L-Y, or C-H-H-R-K-K-0-λ-A-D-L-Y, or C-/3-H-R-K-K-0-Y-A-D-L-Y.

Examples of peptides having at least eleven of the specified amino acids are those having the formula:

α-H-H-R-K-K-G-Y-A-D-L-Y, or

C-jS-H-R-K-K-G-Y-A-D-L-Y, or C-H-H-R-K-K-G-Y-A-D-L-σ, or

C-H-H-5-K-K-G-Y-A-D-L-Y, or

C-H-H-R-K-K-0-Y-A-D-L-Y, or

C-H-H-R-K-K-G-Y-μ-D-L-Y, or C-H-H-R-e-K-G-Y-A-D-L-Y.

Notably, all of the above specific examples of peptide sequences having at least six, seven, eight, nine, ten or eleven of the specified amino acids are provided solely for purposes of illustration and are not intended to be limitative.

It is most preferred, however, as noted above, if the peptide has the sequence:

CHHRKKGYADLY

wherein each residue is as defined previously.

The peptides of the present invention may be synthesized using a standard solid-phase amino acid synthesis or may be provided by the fermentation of recombinant microorganisms. For example, the peptides may be synthesized in accordance with U.S. Patents 4,058,512 and 4,235,772 both of which are incorporated herein in the entirety.

The present peptide may also, as indicated above, be prepared by the fermentation of transformed microorganisms containing a synthetic gene which codes for the present peptide. Conventional techniques may be used for the synthesis of the appropriate gene and for the transformation of a host microorganism. As a host microorganism, E__ coli, for example, may be used. See for example. Current Protocols in Molecular Biology (Wiley Interscience) .

Additionally, the present dodecapeptide may be described, as a short peptide, in terms of its amino acid composition. That is, the present invention may be described in terms of both its amino acid sequence or its amino acid composition. Due to the importance of conformational structure for large peptides in determining peptide activity, the amino acid sequence of large peptides is usually important in maintaining the activity. By contrast, however, for short peptides, activity may often be conserved merely by conserving the amino acid sequence of the peptide without regard to sequence specificity. For example, see Barker, W.C. et al, Protein Seg. Data Anal. (1988) 1:363-373.

In accordance with the present invention, dodecapeptides are provided having the following amino acid composition: one cysteine residue, two histidine residues, one arginine residue, two lysine residues, one glycine residue, two tyrosine residues, one alanine residue, one aspartic acid residue, and a leucine residue, without regard to sequential order.

However, it is preferred if the two histidine residues are adjoining to each other., and independently the two lysine residues are adjoining to each other.

Thus, the present invention also provides a dodecapeptide having the following amino acid composition: one cyoteine residue, two histidine residues, one arginine residue, two lysine residues, one glycine residue, two tyrosine residues, one alanine residue, one aspartic acid residue and a leucine residue, without regard to sequential order, the dodecapeptide having substantially the same activity as the dodecapeptide of the sequence:

CHHRKKGYADLY

wherein C is cysteine, H is histidine, R is arginine, K is lysine, G is glycine, Y is tyrosine, A is alanine, D is aspartic acid and L is leucine.

The phrase "substantially the same activity" is used herein to mean having at least 10% of the activity of the dodecapeptide of the sequence:

CHHRKKGYADLY

as measured by the effect on a μg of peptide per kg of mammalian body weight over a given period of time.

Thus, within the ambit of the above class of dodecapeptides are those whose sequence results from a scrambling of the sequence:

CHHRKKGYADLY

For example, the following sequences are listed hereinbelow for purposes of illustration only and are not intended to be limitative:

CHRKHKGDLYYA

CRKHHKDGYLYA YRCAKHHKDGLY DLYCHRKHKGYA ALYDCHHRKKGY RAYCKHHKGYDL

CKHHRKGYYALD GYDLAYKRKHCH

As with the other dodecapeptide sequences of the present invention, these sequences may be easily synthesized by solid- phase synthesis or prepared by recombinant DNA fermentation.

The present invention will now be further illustrated by reference to certain examples, which are provided solely for illustration and are not intended to be limitative.

Example 1

Studies were initiated for the purpose of generating antibodies to several different sections of a protein called cytochrome b 561. This protein is a polypeptide of 273 amino acids. Several oligopeptides representing a different section of the cytochrome polypeptide were injected into rabbits in order to generate antisera against the specific sections of

the cytochrome. The three peptides tested are those shown below in standard one-letter amino acid abbreviation:

PI (AA247-261) KRPLQAEEQALSMDF P2 (AA130-142) CHHRKKGYADLY P3 (AA21-37) CSMEGPASPARAPGALPYKK

PI corresponds to the cytochrome b 561 carboxy-terminus amino acid sequence Lys(247) - Phe(261) .

The internal peptide P2 contains amino acids His(130) - Tyr(142). A cysteine residue was added at the amino-terminus of P2 as a spacer and to facilitate coupling to carrier proteins.

P3 was composed of the amino-terminal cytochrome b 561 sequence Ser(21) - Tyr(37). A cysteine residue was added at the amino-terminus for coupling to carrier proteins and two lysine residues were added at the carboxy-termi us to increase solubility of the peptide.

These peptides were then coupled chemically to keyhole limpet hemocyanin, a carrier protein, to improve the immunogenicity in rabbits.

Each peptide/carrier conjugate (50 μg of peptide, approximately 30 nanomoles) was injected subcutaneously into three female rabbits (three groups of three rabbits, •approximately 2 months old) . Two weeks later the rabbits were injected again with the same amounts of peptide/carrier conjugate. Thereafter, each rabbit was injected with the

conjugate at approximately monthly intervals and blood samples were drawn. After five months, the rabbits were sacrificed.

Before the first injection, the rabbits were weighed for calculation of anesthetic dose (used to sedate the rabbits during injection) . Before the rabbits were sacrificed, they were weighed again as the rabbits which received P2 were quite obese compared to all other rabbits. The weights of the rabbits before injection and at the end of five months are shown in Figure 1. The average weight of the five injected with peptides Pi and P3 was 4.4 kg. This is normal for adult female rabbits of this type at this age, i.e., the average weight expected at 6 months is 4.5 kg. However, the weights of the rabbits injected with peptide P2 averaged 5.2 kg, approximately 20% higher.

Since no antibodies were made in rabbits injected with P2 (the ones which appeared obese) , two more rabbits were tested. These rabbits were younger, weighing only 2.4 kg at the beginning and the experiment was carried out for an additional two months. Therefore, these rabbits were less than 4 months old when they were weighed and sacrificed. One of these rabbits did make antibodies against P2 peptide and this rabbit did not gain as much weight as the rabbit which did not make antibodies.

Example 2 -

In order to obtain statistically significant data on the effects of peptide P2 on weight gain, another series of

experi ents using mice were performed. Three groups of five mice (BALB/C strain) were used.

The first group received injections of peptide P2, a second group received injections of P3 (as control) , and a third group received injections of saline (as control) . Free peptides were used to avoid the possibility that the effect observed in Example 1 may have been due to the nature of the chemical coupling to the carrier protein.

Each mouse (weighing approximately 15 grams) received an injection of 2.5 μg (1.5 nanomoles) of peptide or saline injected subcutaneously. The mice were weighed three times per week and injected once per week with another 2.5 μg of peptide or saline. After 85 days the mice were sacrificed. The average weight gain for the groups of mice receiving either P2 or P3 peptides is shown in Figure 2.

The P2 peptide delayed weight gain in these mice compared to the control P3 peptide group. However, after 60 days both groups were similar and stayed similar until day 85. Figures 3 and 4 show that even though individual mice varied significantly in their weight every member of the P2 group showed the delay in weight gain compared to the P3 control group. Figure 5 shows that the saline control group did not show a delay in weight gain and was, in fact, not different than the P3 control group.

The above experiments indicate that mice appear to have the opposite response compared with rabbits when both types of animals are injected with peptide P2. Rabbits seem to gain

weight and mice appear to have an inhibition of weight gain. Moreover, the effect of peptide P2 on the mice is to delay normal weight gain up to the end of the second month of weekly peptide administration. However, after the second month normal weight gain is observed. This may be caused by the development of antibodies to the peptide after this period of time. This latter phenomenon appears to be caused by a developmentally specific effect of the peptide or the mice may develop antibodies to the peptide after 60 days of weekly administration and these antibodies may inhibit the effect of the peptide.

Equivalent to the present peptides, for purposes of the present invention, are peptides of the formula:

XfCHHRKKGYADLY)-Z

wherein X and Z are each independently of the other hydrogen or from 1 to 1,000 amino acid residues, and which exhibit the activity of the present peptide or substantially the same activity as the present peptide.

As the amino acid residues, any of the following may be used independently for each of X and Z: glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine, lysine, hydroxylysine, histidine, arginine, phenylalanine, tyrosine, tryptophan, proline and hydroxyproline. The amino acid sequences for each of X and Y may independently be random, block or even long repeating in nature.

The sequence CHHRKKGYADLY may be expected to be active as a part of a larger polypeptide as it is well known to those skilled in the art that the functional part of a protein, particularly a protein involved in binding, can reside in a short sequence of the total polypeptide.

Also equivalent to the present peptides, for purposes of the present invention, are peptides of the general formula:

X-fc.j3γ δe η0λμπpσ-J-Z

wherein at least six and up to and including twelve of the amino acid residues , β , y , δ , e, η , θ , λ, μ, π, p and σ are defined and in the sequential position specified in the sequence:

CHHRKKGYADLY

wherein C is cysteine, H is histidine, R is arginine, K is lysine, G is glycine, Y is tyrosine, A is alanine, D is aspartic acid, and L is leucine, and the remaining amino acids are each independently glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, asparagine, glutamine, lysine, hydroxy lysine, histidine, arginine, phenylalanine, tyrosine, tryptophan, proline- or hydroxyp ^' roline; and X and Z are as defined above.

The dodecapeptide of the present invention may be administered by itself or as a component of a composition. Generally, whether administered by itself or as part of a

composition, from about 10 μg to about 1,000 μg of peptide per kg of body weight of mammalian host is administered. The present peptide, either by itself or as part of a composition, may be administered to any mammal, such as mice, rabbits, dogs or cats, particularly humans, however.

In addition to the above range, lesser or greater amounts may be used.

The present peptide is water-soluble, and is preferably administered either intravenously or subcutaneously. The peptide may be conveniently administered in dextrose 5% saline or in saline solution.

The present peptide may. also be microencapsulated in a lipid vesicle in accordance with a conventional encapsulation technique well known to those skilled in the art.

Compositions containing the present peptide may also be used. The compositions will generally contain the peptide and a conventional pharmaceutically acceptable carrier known to those skilled in the art. Generally, however, it is preferred that liquid compositions be used which are suitable for intravenous or subcutaneous injection. Examples of liquid carriers are saline solution, dextrose 5% saline solution or water, all of which are suitable for injection.

When the above liquids are used for injection, particularly for humans, it is desirable, if not essential, that they be sterile so as to be suitable for injection.

In the liquid composition, the peptide may, in general, comprise from about 10 ^"7 g to 10 ^"3 g/g of liquid carrier. Concentrations less or greater than this may be used, however.

Additionally, it is noted that the present peptide may be administered in conjunction with other ingredients in the composition, such as, for example, hormones and vitamins.

In accordance with another aspect of the present invention, antibodies may be prepared against the present peptides using methodologies as described in U.S. Patents 4,151,268, 4,197,237 and 4,123,431. Each and all of these patents are hereby incorporated in the entirety herein.

Further, monoclonal antibodies against the present peptides can be prepared using conventional methodologies. In turn, these monoclonal antibodies may be used to identify the present peptides to detect and quantify the present peptides, or even to purify the present peptides by immunoaffinity chromatography.

Additionally, in accordance with the present invention, antibodies may be used to attenuate the effect of the present peptide in a host.

Finally, it is noted that any number of techniques may be used, in accordance with the present invention, for rendering the present peptides immunogenic.

For example, the present peptides may be rendered immunogenic by conjugation with muramyl peptides as described

in U.S. Patents 4,639,512 and 4,461,761. Also, the present peptides may be rendered immunogenic by conjugation with other polypeptides as described in U.S. Patent 4,812,554. Each of U.S. Patents 4,639,512, 4,461,761 and 4,812,554 are incorporated herein in the entirety.

By raising antibodies to the present peptides, an assay procedure can be used for the peptides in accordance with known methodologies.

Having described the present invention, it will be apparent to one skilled in the art that many changes and modifications can be made to the embodiments described above without departing from the spirit and the scope of the present invention.