Studies on the proteolytic inactivation and the limited proteolysis of the arom pentafunctional enzyme conjugate of Neurospora crassa

Technical Report · Tue Aug 01 00:00:00 EDT 1978

OSTI ID:6341404

Vitto, A

The arom enzyme system of Neurospora crassa is a pentafunctional enzyme conjugate that catalyzes five consecutive reactions in the synthesis of the aromatic amino acids. This conjugate is formed from two identical polypeptides in each of which reside the five enzymes of the arom system. Purified arom was exposed to trypsin, chymotrypsin, and a protease preparation from Neurospora in the presence and absence of the first substrate, 3-deoxy-D-arabino-heptulosonate 7-phosphate. In the absence of this substrate, the proteolytic inactivations of all five enzymes follow first-order kinetics, with the exception of the tryptic and chymotryptic inactivations of the third enzyme, dehydroshikimate reductase, which follow a biphasic loss of activity. The second, third, and fifth enzymes of the arom system have similar stabilities and are all relatively resistant to proteolytic inactivation. The first enzyme in the pathway, dehydroquinate synthase, is much more sensitive to proteolysis; however, the fourth enzyme, shikimate kinase, is by far the most sensitive. The order of enzyme loss remains the same regardless of the protease used to inactivate.

• Research Organization: Tennessee Univ., Knoxville (USA)
• DOE Contract Number: EY-76-C-05-0033
• OSTI ID: 6341404
• Report Number(s): TID-29020
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
BIOSYNTHESIS
CARBOXYLIC ACIDS
CATALYSIS
CHEMICAL REACTIONS
CHYMOTRYPSIN
DATA
DATA FORMS
DECOMPOSITION
ENZYMES
EXPERIMENTAL DATA
FUNGI
GRAPHS
HYDROLASES
INACTIVATION
INFORMATION
METABOLISM
NEUROSPORA
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
PLANTS
PROTEOLYSIS
SYNTHESIS
TRYPSIN