Nov 18, 1975

The behavior of holo- and apo-forms of bovine superoxide dismutase at low pH

Biochimica Et Biophysica Acta
J A Fee, W D Phillips

Abstract

1. Holo-superoxide dismutase from bovine erythrocytes has been shown to undergo a reversible structural modification in the pH 3-5 range. 2. The spectral alterations observed on changing from neutrality to pH 2 were: a slight attenuation of the 680 nm absorbance; the loss of the 450 nm shoulder, apparent in the optical spectrum of the native protein; and a new band appeared at 330 nm. The circular dichroism at 600 nm was essentially lost while a weak negative band appeared at approx. 380 nm and a positive band at 310 nm. 3. The EPR spectrum was also modified on changing from the native to the low pH form: A parallel increased from approximately 130 to approximately 150 G, g parallel remained unchanged at approximately 2.27, and gm decreased from approximately 2.09 to approximately 2.08. The apparent linewidth remained essentially constant. 4. High resolution (220 MHz) PMR spectra of holo- and apoproteins revealed that the metals influence the three-dimensional structure of the protein. 5. PMR studies indicated that at pH 3 the apoprotein existed almost entirely in a random coil form and that it assumed a compact well-ordered structure on returning to neutral pH. The holoprotein maintained a compact, apparently dimeric, structur...Continue Reading

Mentioned in this Paper

In Vivo NMR Spectroscopy
Apoenzymes
Bos taurus
Plasma Protein Binding Capacity
Protein Conformation
Spectrophotometry, Ultraviolet
Specimen Type - Erythrocytes
Spectrophotometry
Red Blood Cell Count Measurement
Circular Dichroism, Vibrational

About this Paper

Related Feeds

Cajal Bodies & Gems

Cajal bodies or coiled bodies are dense foci of coilin protein. Gemini of Cajal bodies, or gems, are microscopically similar to Cajal bodies. It is believed that Cajal bodies play important roles in RNA processing while gems assist the Cajal bodies. Find the latest research on Cajal bodies and gems here.