PURIFICATION, CHARACTERIZATION AND BIOGENESIS OF COMPLEX III FROM YEAST MITOCHONDRIA.
Item
-
Title
-
PURIFICATION, CHARACTERIZATION AND BIOGENESIS OF COMPLEX III FROM YEAST MITOCHONDRIA.
-
Identifier
-
AAI8302553
-
identifier
-
8302553
-
Creator
-
SIDHU, ANITA.
-
Contributor
-
Diana S. Beattie
-
Date
-
1983
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Biology, General
-
Abstract
-
Complex III was isolated and purified from bakers' yeast by ammonium sulfate fractionation and column chromatography. The purified complex contained 7.03 and 4.24 nmol/mg protein of cytochromes b and c(,1), respectively. The specific activity of the complex was 17.1 (mu)mol/min/mg protein. Electrophoresis of the complex revealed the presence of seven polypeptides with molecular weights from 15,500 to 50,000. The isoelectric points of these subunits and their stoichiometry were determined.;The two core proteins and the iron-sulfur protein were purified, and antibodies againt these subunits and complex III were raised. Electrophoretic analysis of the immunoprecipitates also confirm the presence of seven polypeptides in complex III with molecular weights from 15,000 to 47,000.;The topology of the subunits was studied by proteolytic digestion and immunoinhibition studies. The two core proteins appear to be embedded within the complex, while cytochromes b and c(,1), the iron-sulfur protein and the 17,500-dalton subunit are substantially exposed to the surface.;Subunit interactions of complex III were studied by dissociation of mitochondria in low concentrations of SDS. Cytochromes b, c(,1) and core protein I appear to be tightly associated and lie close together. The iron-sulfur protein and the 17,500-dalton subunit are loosely attached to the complex.;Studies on the biogenesis of complex III indicates that only cytochrome b is synthesized on mitochondrial ribosomes. Pulse-labeling of (('3)H)leucine labeled cells with (('35)S)methionine, followed by calculations of the half-life of the subunits suggests that core protein I and the iron-sulfur protein have large pools and low turn-over rates. Cytochromes b and c(,1) appear to have small precursor pools and high turn-over rates.;Studies on diuron-resistant mutants of yeast show that these mutants are resistant to diuron in vitro and are not cross-resistant to antimycin or UHDBT. The mutants contained similar quantities of cytochromes a, b, and c(,1) as the wild-type. No "extra reduction" of cytochrome b was observed in these mutants.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
-
Program
-
Biochemistry
