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Differential Solubility of Racemic Mixtures of Amino Acids*
748
RESEARCH NOTES TABLE 1.—Summary 0} seven hatches Tray materials
Fertile eggs (no.) Hatchability (%) Normal poults (no.) Normal poults (%) Spraddle poults (no.) Spraddle poults ( % ) d
Cloth
Wire
Rubber
1,436 75.1 829 76.9 249 23.1
1,510 71.5 997 92.4b 82 7.6
1,524 78. l a 1157 97.2" 33 2.8
percentage of normal poults. The increase in the percentage of normal poults hatched on wire and rubber mat was significant (P<.05) and (P<.01) respectively when compared to the normal poults hatched on crinoline. CONCLUSIONS
* Significantly different from wire at the 5% level. Significantly different from cloth at the 5% level. Significantly different from cloth at the 1% level. Spraddles have the same significant differences as normals.
b c
showed no significant difference between the crinoline and rubber mat or wire at the 5% level of probability, but there was a significant difference between the wire and rubber mat (P < .05) in favor of the rubber mat. In the seven settings, there was only one hatch where hatchability of eggs on wire was as good or better than the hatchability of eggs on crinoline or rubber mat. The authors have no explanation for this. In this paper, the term normal poults refers to all poults hatched which were not spraddle-legged. Spraddles were those poults with their legs spread apart and were down and unable to walk. The wire and rubber mat coverings improved the
The fly screen wire and rubber mat as used decreased the percentage of spraddlelegged poults significantly. Wire reduced the hatchability of fertile eggs when compared to the rubber mats. The percentage of normal poults varied with the coarseness of the material. REFERENCES Cline, L. E., 1939. Turkeys—Production—Marketing—Diseases. Bulletin 86, University of Nevada, Reno, Nevada. Marsden, S. J., and J. H. Martin, 1955. Turkey Management. Interstate, Danville, Illinois. Snedecor, G. W., 1956. Statistical Methods. 5th Ed., Iowa State University Press, Ames, Iowa. Voris, J. C , and F. T. Shultz, 1962. The Effect of crinoline cloth and crowding of turkey eggs on hatchability and spraddle legged poults. Poultry Sci. 41: 337-338. Weeks, J. P., 1952. The Poultry Profit Guide. Vulcan Service Co., Inc., Birmingham, Alabama.
DIFFERENTIAL SOLUBILITY OF RACEMIC MIXTURES OF AMINO ACIDS* RICHARD D. CREEK Department of Poultry Science, University of Maryland, College Park, Maryland 20742 (Received for publication February 21, 1969)
It has been standardly taught in biochemistry and nutrition courses that the only differences in physical and chemical properties of D and L amino acids is the direction in which solutions of them rotate polarized light. Thus, the separation of the * Scientific Article No. A1499, Contribution No. 4148 of the Maryland Agricultural Experiment Station (Department of Poultry Science.)
desired isomer from a racemic mixture was and still is believed by many to be very difficult or impossible. The purpose of this note is to point out differences in solubility of the various isomers and racemic mixtures, and to suggest that this could lead to a possible method of separation. The data are presented in Table 1. There is no consistent pattern. In some
749
RESEARCH NOTES TABLE 1.—Solubilities of amino acids in grams per kilogram of water at 25°C. Name L-Alanine L-Alanine L-Alanine L-Alanine DL-Alanine L-Aspartic acid L-Aspartic acid DL-Aspartic acid
Source * '
2 3
' '
4 1
gm./kg. H 2 0 167.2 166.5 167.0 167.0 167.2 5.0 4.98 7.78
L-Cystine D-Cystine Meso Cystine DL-Cystine
' ' ' '
0.1096 0.108 0.056 0.049
Diodo-L-Tyrosine Diodo-DL-Tyrosine
' 1
0.617 0.340
L-Glutamic acid L-Glutamic acid DL-Glutamic acid L-Isoleucine L-Isoleucine DL-Isoleucine L-Leucine L Leucine L-Leucinc L-Leucine L-Leucine DL-Leucine L-Methionine L-Methionine DL-Methionine
'
3
' '
4 1 J l 1 4 3
' 3 4 x
L-Phenylalanine L-Phenylalanine L-Phenylalanine DL-Phenylalanine
3
L-Serine DL-Serine
4
L-Tyrosine L-Tyrosine DL-Tyrosine D-Tyrosine
4
4 1
'
8.64 8.58 20.54 41.17 34.5 22.29 24.26 21.9 22.0 21.7 21.6 9.91 55.9 56.2 33.81 28.0 27.6 29.65 14.11
cases the values are practically identical, but in others the DL form may be much lower or much higher than the L form. It is unfortunate that more data was not available to compare the solubility of both isomers and the racemic mixture. Of practical interest is the difference in solubility of L and DL-methionine. In view of its higher solubility the L form might be more easily absorbed; however, the fluid of the small intestine differs considerably from pure water at 25° C. and it is possible that these differences are insignificant. It would appear that if large differences in solubility between the optical isomers occured that a saturated solution could be cooled and that the least soluble isomer would precipitate first. Buss and Vermeulen (1968), in a thorough review of this problem, present considerable information on the combination of an optical isomer with the opposite isomer of some other compound and precipitating the combination as a salt. The problem is not confined to amino acids nor the poultry industry (Buss and Vermeulen, 1968). The poultry industry is extremely lucky that the chickens can use both isomers and the hydroxy analog of methionine, the amino acid usually found to be first limiting in diets. REFERENCES
L-Valine L-Valine DL-Valine 1
L
3 J i l 4
i
422. 50.23 0.454 0.451 0.351 0.453 88.5 58.1 70.9
1966-1967, Handbook of Chemistry and Physics. 1960, The Merck Index. 1963, Nozaki and Tanford. 4 1968, Handbook of Biochemistry. 2 3
Buss, D. R., and T. Vermeulen, 1968. Optical isomer separation. Ind. Eng. Chem. 60:12-28. Handbook of Chemistry and Physics. 47th Edition, 1966-1967. Chemical Rubber Company, Cleveland, Ohio. 44128. Handbook of Biochemistry, H. A. Sober, Editor. 1st Edition, 1968. Chemical Rubber Co., Cleveland, Ohio. 44128. The Merck Index, Seventh Edition. Merck & Company, Rahway, New Jersey. Nozaki, Y., and C. H. Tanford, 1963. The solubility of amino acids and related compounds in aqueous urea solutions. J. Biol. Chem. 238: 4074,-4081
RESEARCH NOTES TABLE 1.—Summary 0} seven hatches Tray materials
Fertile eggs (no.) Hatchability (%) Normal poults (no.) Normal poults (%) Spraddle poults (no.) Spraddle poults ( % ) d
Cloth
Wire
Rubber
1,436 75.1 829 76.9 249 23.1
1,510 71.5 997 92.4b 82 7.6
1,524 78. l a 1157 97.2" 33 2.8
percentage of normal poults. The increase in the percentage of normal poults hatched on wire and rubber mat was significant (P<.05) and (P<.01) respectively when compared to the normal poults hatched on crinoline. CONCLUSIONS
* Significantly different from wire at the 5% level. Significantly different from cloth at the 5% level. Significantly different from cloth at the 1% level. Spraddles have the same significant differences as normals.
b c
showed no significant difference between the crinoline and rubber mat or wire at the 5% level of probability, but there was a significant difference between the wire and rubber mat (P < .05) in favor of the rubber mat. In the seven settings, there was only one hatch where hatchability of eggs on wire was as good or better than the hatchability of eggs on crinoline or rubber mat. The authors have no explanation for this. In this paper, the term normal poults refers to all poults hatched which were not spraddle-legged. Spraddles were those poults with their legs spread apart and were down and unable to walk. The wire and rubber mat coverings improved the
The fly screen wire and rubber mat as used decreased the percentage of spraddlelegged poults significantly. Wire reduced the hatchability of fertile eggs when compared to the rubber mats. The percentage of normal poults varied with the coarseness of the material. REFERENCES Cline, L. E., 1939. Turkeys—Production—Marketing—Diseases. Bulletin 86, University of Nevada, Reno, Nevada. Marsden, S. J., and J. H. Martin, 1955. Turkey Management. Interstate, Danville, Illinois. Snedecor, G. W., 1956. Statistical Methods. 5th Ed., Iowa State University Press, Ames, Iowa. Voris, J. C , and F. T. Shultz, 1962. The Effect of crinoline cloth and crowding of turkey eggs on hatchability and spraddle legged poults. Poultry Sci. 41: 337-338. Weeks, J. P., 1952. The Poultry Profit Guide. Vulcan Service Co., Inc., Birmingham, Alabama.
DIFFERENTIAL SOLUBILITY OF RACEMIC MIXTURES OF AMINO ACIDS* RICHARD D. CREEK Department of Poultry Science, University of Maryland, College Park, Maryland 20742 (Received for publication February 21, 1969)
It has been standardly taught in biochemistry and nutrition courses that the only differences in physical and chemical properties of D and L amino acids is the direction in which solutions of them rotate polarized light. Thus, the separation of the * Scientific Article No. A1499, Contribution No. 4148 of the Maryland Agricultural Experiment Station (Department of Poultry Science.)
desired isomer from a racemic mixture was and still is believed by many to be very difficult or impossible. The purpose of this note is to point out differences in solubility of the various isomers and racemic mixtures, and to suggest that this could lead to a possible method of separation. The data are presented in Table 1. There is no consistent pattern. In some
749
RESEARCH NOTES TABLE 1.—Solubilities of amino acids in grams per kilogram of water at 25°C. Name L-Alanine L-Alanine L-Alanine L-Alanine DL-Alanine L-Aspartic acid L-Aspartic acid DL-Aspartic acid
Source * '
2 3
' '
4 1
gm./kg. H 2 0 167.2 166.5 167.0 167.0 167.2 5.0 4.98 7.78
L-Cystine D-Cystine Meso Cystine DL-Cystine
' ' ' '
0.1096 0.108 0.056 0.049
Diodo-L-Tyrosine Diodo-DL-Tyrosine
' 1
0.617 0.340
L-Glutamic acid L-Glutamic acid DL-Glutamic acid L-Isoleucine L-Isoleucine DL-Isoleucine L-Leucine L Leucine L-Leucinc L-Leucine L-Leucine DL-Leucine L-Methionine L-Methionine DL-Methionine
'
3
' '
4 1 J l 1 4 3
' 3 4 x
L-Phenylalanine L-Phenylalanine L-Phenylalanine DL-Phenylalanine
3
L-Serine DL-Serine
4
L-Tyrosine L-Tyrosine DL-Tyrosine D-Tyrosine
4
4 1
'
8.64 8.58 20.54 41.17 34.5 22.29 24.26 21.9 22.0 21.7 21.6 9.91 55.9 56.2 33.81 28.0 27.6 29.65 14.11
cases the values are practically identical, but in others the DL form may be much lower or much higher than the L form. It is unfortunate that more data was not available to compare the solubility of both isomers and the racemic mixture. Of practical interest is the difference in solubility of L and DL-methionine. In view of its higher solubility the L form might be more easily absorbed; however, the fluid of the small intestine differs considerably from pure water at 25° C. and it is possible that these differences are insignificant. It would appear that if large differences in solubility between the optical isomers occured that a saturated solution could be cooled and that the least soluble isomer would precipitate first. Buss and Vermeulen (1968), in a thorough review of this problem, present considerable information on the combination of an optical isomer with the opposite isomer of some other compound and precipitating the combination as a salt. The problem is not confined to amino acids nor the poultry industry (Buss and Vermeulen, 1968). The poultry industry is extremely lucky that the chickens can use both isomers and the hydroxy analog of methionine, the amino acid usually found to be first limiting in diets. REFERENCES
L-Valine L-Valine DL-Valine 1
L
3 J i l 4
i
422. 50.23 0.454 0.451 0.351 0.453 88.5 58.1 70.9
1966-1967, Handbook of Chemistry and Physics. 1960, The Merck Index. 1963, Nozaki and Tanford. 4 1968, Handbook of Biochemistry. 2 3
Buss, D. R., and T. Vermeulen, 1968. Optical isomer separation. Ind. Eng. Chem. 60:12-28. Handbook of Chemistry and Physics. 47th Edition, 1966-1967. Chemical Rubber Company, Cleveland, Ohio. 44128. Handbook of Biochemistry, H. A. Sober, Editor. 1st Edition, 1968. Chemical Rubber Co., Cleveland, Ohio. 44128. The Merck Index, Seventh Edition. Merck & Company, Rahway, New Jersey. Nozaki, Y., and C. H. Tanford, 1963. The solubility of amino acids and related compounds in aqueous urea solutions. J. Biol. Chem. 238: 4074,-4081