Arom enzyme conjugate of neurospora: multiple proteases and subunit artifacts

Conference · Sat Dec 31 23:00:00 EST 1977

OSTI ID:7277213

Gaertner, F. H.; Vitto, A.; Allison, D.; Cole, K. W.; Spady, G. E.

The arom enzyme conjugate of Neurospora crassa is a multifunctional protein consisting of five enzymes which catalyze a sequennce of reactions leading to the biosynthesis of the aromatic amino acids. Previously, it was believed that this multienzyme system consisted of a set of physically associated but noncovalently linked enzymes. We now have good evidence that all five activities reside on a single polypeptide chain, and electron micrographs confirm that the enzyme conjugate is a dimer of this multifunctional polypeptide. The enzyme conjugate is very susceptible to proteolytic attack. However, a number of discrete proteolytic clips can occur before the system loses either its overall native structure or any one of its five activities. The uncontrolled action of a multiplicity of resident proteases in N. crassa during the extraction and purification of the conjugate led us to the false conclusion that this enzyme system consisted of noncovalently linked enzymes. Which of the many proteases that appear to be present in N. crassa are primarily involved in forming the artifactual subunits remains to be determined.

• Research Organization: Tennessee Univ., Oak Ridge (USA). School of Biomedical Sciences; Oak Ridge National Lab., Tenn. (USA)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 7277213
• Report Number(s): CONF-780433--1
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
BIOCHEMICAL REACTION KINETICS
BIOMASS
BIOSYNTHESIS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DECOMPOSITION
ENERGY SOURCES
ENZYMES
FUNGI
HYDROLASES
KINETICS
METABOLISM
NEUROSPORA
ORGANIC ACIDS
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
PLANTS
PROTEINS
PROTEOLYSIS
REACTION KINETICS
RENEWABLE ENERGY SOURCES
SYNTHESIS