Hoffmann R J
Biochem Genet. 1985 Dec;23(11-12):859-76. doi: 10.1007/BF00499934.
The phosphoglucomutase (Pgm) locus from populations of the sea anemone Metridium senile has three alleles in natural populations from the northeastern coast of North America. Two of the alleles exhibit clinal variation north of Cape Cod, suggesting a possible association of allele frequency with environmental temperature. This clinal pattern is reproducible and stable over at least brief periods of time. The allozymes encoded by each of the six Pgm genotypes have been partially purified and characterized. The symmetrical pH optimum for Vmax is pH 7.5; the apparent Km (Kmapp) of glucose-1-phosphate declines monotonically as the pH increases from 6.5 to 8.5. There are no pronounced differences in heat stabilities of PGM produced by various genotypes, nor are there significant differences in specific activities. There are no differences in the sensitivity of Vmax to temperature. Kmapp values are very low for all genotypes, ranging from about 2 to 12 microM, depending upon the temperature. Kmapp of glucose-1-phosphate declines as the temperature is raised for all genotypes, whether the pH is held constant or allowed to vary with the temperature. Under certain conditions, there are small significant differences among genotypes in Kappm values, but there is no systematic pattern to these differences. The present data provide no biochemical explanation for the maintenance of the Pgm cline by selection for functional differences under different thermal regimes.
海葵衰老梅氏海葵种群中的磷酸葡萄糖变位酶（Pgm）基因座在北美东北海岸的自然种群中有三个等位基因。其中两个等位基因在科德角以北呈现渐变变异，这表明等位基因频率可能与环境温度有关。这种渐变模式至少在短时间内是可重复且稳定的。已对六种Pgm基因型各自编码的同工酶进行了部分纯化和表征。Vmax的对称最适pH值为7.5；随着pH值从6.5增加到8.5，葡萄糖-1-磷酸的表观Km（Kmapp）单调下降。不同基因型产生的PGM的热稳定性没有明显差异，比活性也没有显著差异。Vmax对温度的敏感性没有差异。所有基因型的Kmapp值都非常低，根据温度不同，范围约为2至12微摩尔。无论pH值保持恒定还是随温度变化，随着温度升高，所有基因型的葡萄糖-1-磷酸的Kmapp值都会下降。在某些条件下，基因型之间的Kappm值存在微小但显著的差异，但这些差异没有系统的模式。目前的数据没有为在不同热条件下通过选择功能差异来维持Pgm渐变提供生化解释。
