Abstract
Enzymatic parameters of aminopeptidase-I that may be sensitive to temperature and solute variations were investigated to provide a functional explanation for specific activity differences among genotypes in natural populations. The effect of temperature on the apparent K m of l-leucyl-4-methoxy-2-naphthylamide and the dipeptide phenylalanyl-glycine was small, especially between 10 and 25 C. The apparent K m varied only between 36.7 and 49.8 µM at these temperatures and the six common genotypes did not differ in temperature-dependent substrate affinities. While pH had a significant effect on K m , no differences among genotypes were observed. Activation enthalpies were also identical among genotypes. Thermal inactivation was slowest at 15 C and the same for all genotypes. Of 18 tested amino acids, only phenylalanine inhibited aminopeptidase-I; K I values ranged from 1.2 to 0.8 mM and were the same for all genotypes. Small differences among genotypes were detected in the inhibitory effect of zinc. The concentration of aminopeptidase-I enzyme was the same for all genotypes in a population exposed to oceanic salinity, but the concentration of Lap 94/94was 15% lower than that of other genotypes in a population experiencing estuarine salinity. Genotypes with the Lap 94allele exhibited higher apparent k cat values in all population samples. The probable genotype-dependent effects of enzyme concentration and k cat differences are discussed with regard to maintenance of the polymorphism and genetic differences among populations.
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Bayne, B. L., Moore, M. N., and Koehn, R. K. (1981). Lysosomes and the response by Mytilus edulis L. to an increase in salinity. Mar. Biol. Lettrs. 2193.
Bishop, S. H. (1976). Nitrogen metabolism and excretion: Regulation of intracellular amino acid concentrations. In Wiley, M. (ed.), Estuarine Processes, Vol. 1 Academic Press, New York, pp. 414–429.
Bowlus, R. D., and Somero, G. N. (1979). Solute compatability with enzyme function and structure: Rationales for the selection of osmotic agents and end-products of anaerobic metabolism in marine invertebrates. J. Exp. Zool. 208137.
Boyer, J. F. (1974). Clinal and size-dependent variation at the Lap locus in Mytilus edulis. Biol. Bull. 147535.
Bricteux-Gregoire, S., Duchâteau-Bosson, G., Jeuniaux, C., and Florkin, M. (1964). Constituants osmotiquement actifs des muscles adducteurs de Mytilus edulis adaptée à l'eau ou à l'eau saumâtre. Arch. Int. Physiol. Biochem. 72116.
Clarke, B. (1975). The contribution of ecological genetics to evolutionary theory: Detecting the direct effects of natural selection on particular polymorphic loci. Genetics 79s101.
Cornish-Bowden, A. (1976). The effect of natural selection on enzymatic catalysis. J. Mol. Biol. 1011.
Gartner-Kepkay, K. E., Dickie, L. M., Freeman, K. R., and Zouros, E. (1980). Genetic differences and environments of mussel populations in the maritime provinces. Can. J. Fish. Aquat. Sci. 37775.
Geuffory, D. E. (ed.) (1975). A guide for the preparation and use of buffers in biological systems, Calbiochem, La Jolla, Calif.
Hazel, J. R., and Prosser, C. L. (1974). Molecular mechanisms of temperature compensation in poikilotherms. Physiol. Rev. 54620.
Koehn, R. K. (1978a). Biochemical aspects of genetic variation of the Lap locus in Mytilus edulis. In Battaglia, B., and Beardmore, J. A. (eds.), Genetics and Ecology of Marine Organisms Plenum, New York, pp. 211–227.
Koehn, R. K. (1978b). Physiology and biochemistry of enzyme variation: The interface of ecology and population genetics. In Brussard, P., and Solbrig, O. (eds.), The Interface of Ecology and Genetics Springer-Verlag, Berlin, pp. 51–72.
Koehn, R. K., and Immermann, F. (1981). Biochemical studies of the aminopeptidase-1 polymorphism in Mytilus edulis. I. Dependence of enzyme activity on season, tissue and genotype. Biochem. Genet. 191115.
Koehn, R. K., and Mitton, J. B. (1972). Population genetics of marine pelecypods. I. Ecological heterogeneity and evolutionary strategy at an enzyme locus. Am. Natur. 10646.
Koehn, R. K., Milkman, R., and Mitton, J. B. (1976). Population genetics of marine pelecypods. IV. Selection, migration and genetic differentiation in the blue mussel, Mytilus edulis. Evolution 302.
Koehn, R. K., Hall, J. G., and Zera, A. (1980a). Parallel variation of genotype-dependent aminopeptidase-I activity between Mytilus edulis and Mercenaria mercenaria. Mar. Biol. Lett. 1245.
Koehn, R. K., Newell, R. I. E., and Immermann, F. (1980b). Maintenance of an aminopeptidase allele frequency cline by natural selection. Proc. Natl. Acad. Sci. USA 775385.
Koehn, R. K., Bayne, B. L., Moore, M. N., and Siebenaller, J. F. (1980c). Salinity related physiological and genetic differences between populations of Mytilus edulis. Biol. J. Linn. Soc. 14319.
Lassen, H. H., and Turano, F. J. (1978). Clinal variation and heterozygote deficit at the Lap-locus Mytilus edulis. Mar. Biol. 49245.
Laurell, C. B. (1966). Quantitative estimation of proteins by electrophoresis in agarous gels containing antibodies. Anal. Biochem. 1545.
Levinton, J. (1973). Genetic variation in a gradient of environmental variability: Marine Bivalvia (Mollusca). Science 18075.
Levinton, J., and Koehn, R. K. (1976). Population genetics of mussels. In Bayne, B. L. (ed.), Marine Mussels: Their Ecology and Physiology Cambridge University Press, Cambridge, pp. 357–384.
Levinton, J., and Lassen, H. H. (1978a). Selection, ecology, and evolutionary adjustment within bivalve mollusc populations. Phil. Trans. Roy. Soc. Lond. B 284403.
Levinton, J. S., and Lassen, H. H. (1978b). Experimental mortality studies and adaptation at the Lap locus in Mytilus edulis. In Battaglia, B., and Beardmore, J. A. (eds.), Genetics and Ecology of Marine Organisms Plenum, New York, pp. 229–254.
Lewontin, R. C. (1974). The Genetic Basis of Evolutionary Change Columbia University Press, New York.
Mahadevan, S., and Tappel, A. L. (1967). Arylamidases of rat liver and kidney. J. Biol. Chem. 242369.
Milkman, R., and Beaty, L. D. (1970). Large-scale electrophoretic studies of allelic variation in Mytilus edulis. Biol. Bull. 139430.
Milkman, R., and Koehn, R. K. (1977). Temporal variation in the relationship between size, numbers and an allele-frequency in a population of Mytilus edulis. Evolution 31103.
Mitton, J. B., Koehn, R. K., and Prout, T. (1973). Population genetics of marine pelecypods. II. Epistasis between functionally related isoenzymes of Mytilus edulis. Genetics 73487.
Moore, M. N., Koehn, R. K., and Bayne, B. L. (1980). Leucine aminopeptidase (aminopeptidase-I), N-acetyl-β-hexoseaminidase and lysosomes in the mussel Mytilus edulis L., in response to salinity changes. J. Exp. Zool. 214239.
Nicholson, J. A., and Kim, Y. S. (1975). A one-step L-amino acid oxidase assay for intestinal peptide hydrolase activity. Anal. Biochem. 63110.
Theisen, B. F. (1978). Allozyme clines and evidence of strong selection in three loci in Mytilus edulis L. (Bivalvia) from Danish waters. Ophelia 17135.
Young, J. P. W., Koehn, R. K., and Arnheim, N. (1979). Biochemical characterization of “Lap,” a polymorphic aminopeptidase from the blue mussel, Mytilus edulis. Biochem. Genet. 17305.
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This research was supported by National Science Foundation Grant DEB 7908802 and USPHS Grant GM 21133 to R. K. Koehn and USPHS Postdoctoral Fellowship GM 06728 to J. F. Siebenaller. This is contribution No. 372 from the Program in Ecology and Evolution, State University of New York, Stony Brook.
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Koehn, R.K., Siebenaller, J.F. Biochemical studies of aminopeptidase polymorphism in Mytilus edulis. II. Dependence of reaction rate on physical factors and enzyme concentration. Biochem Genet 19, 1143–1162 (1981). https://doi.org/10.1007/BF00484570
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DOI: https://doi.org/10.1007/BF00484570