ISSN:
1432-1432
Keywords:
Drosophila acid phosphatase
;
Subunit hybridization
;
CRM tests
;
Heterospecific enzyme
;
Amino acid substitutions
;
Subunit contact
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary The dimeric enzyme, acid phosphatase-1, was partially purified from eleven species of the genus Drosophila. Dissociated subunits were mixed and allowed to reassociate in forty-one interspecific combinations. In each so-called “quantitative subunit hybridization test”, the relative activities of the heterospecific and the two homospecific enzymes were determined by densitometry. In 34 of the 41 tests significant differences between observed and expected homospecific: heterospecific enzyme activity ratios were detected. The differences ranged from a four-fold excess of the heterospecific enzyme to over a six-fold excess of the homospecific enzymes. In order to measure the enzyme activities on a protein basis, fifteen heterospecific enzymes were purified and used as antigens in CRM tests. The antisera were diluted such that only the homologous subunit in the heterospecific enzyme complexed the acid phosphatase antibodies. The results from each CRM test show that the heterospecific enzymes is only one-half as antigenic as the homologous homospecific enzyme, when the two are adjusted to equal catalytic activities. Thus, the differences between observed and expected levels of acid phosphatase activity measured by the quantative subunit hybridization technique apparently reflect differences in the relative amounts of protein which form during subunit reassociation. The technique, then, appears to detect differences in acid phosphatase subunit affinities. The data either taken directly from the 41 interspecific tests or in terms of the average difference between each two species in third species tests were used to construct phenograms. The species relationships depicted in both phenograms were very different from their actual phylogenetic relationships. This method, then, is not useful as an evolutionary metric. The differences between observed and expected heterospecific:homospecific enzyme ratios may be due to a relatively large number of amino acid substitutions if acid phosphatase subunits pair isologously.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01733264
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