Active-Site Heterogeneity as Revealed by Peroxide and Mercury: Interactions with Purified Subunits of Limulus Hemocyanin
| Autor: | Richard W. Topham, Celia Bonaventura, Shirley Tesh, Joseph Bonaventura |
|---|---|
| Rok vydání: | 1986 |
| Předmět: |
biology
Protein subunit medicine.medical_treatment Active site chemistry.chemical_element chemical and pharmacologic phenomena Hemocyanin biology.organism_classification Peroxide Mercury (element) Absorbance chemistry.chemical_compound Biochemistry chemistry Limulus biology.protein medicine Hydrogen peroxide |
| Zdroj: | Invertebrate Oxygen Carriers ISBN: 9783540169437 |
| DOI: | 10.1007/978-3-642-71481-8_68 |
| Popis: | Previous work has shown that the active sites of mollusc and arthropod hemocyanins may be differentiated by their interactions with hydrogen peroxide and with mercury. In contrast to mollusc hemocyanins, the arthropod hemocyanins are typically oxidized by hydrogen peroxide and are susceptible to loss of copper after mercury incubation. We have undertaken studies of peroxide and mercury interactions with native hemocyanins and their fractionated subunits to gain a better understanding of the extent and significance of active-site heterogeneity. We selected whole, stripped and fractionated forms of Limulus hemocyanin for detailed study, concentrating on Ip IIIA because of its unique characteristics. Lp IIIA, unlike the other subunits of Limulus hemocyanin and other arthropod hemocyanins in general, has the ability to catalyze the decomposition of hydrogen peroxide without loss of 340 nm absorbance. Also, Lp IIIA upon long-term storage slowly loses 340 nm absorbance, an aging process that can be reversed by hydrogen peroxide. It does not undergo extended self-aggregation in the presence of mercury as do the other subunits, and it loses more 340 nm absorbance than other subunits upon mercury treatment and subsequent EDTA dialysis. These exceptional characteristics make subunit IIIA of Limulus hemocyanin an outstanding candidate for detailed active-site study. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|