Skip to main content
ARS Home » Research » Publications at this Location » Publication #123885
Title: THE EFFECT OF TEMPERATURE ON IAA TURNOVER AND BIOSYNTHESIS

Author
item RAPPORINI, FRANCESCA - INST ECOPHYL FRUIT TREES
item TAM, YUEN YEE - UNIV OF MASSACHUSETTS
item COHEN, JERRY - UNIV OF MINNESOTA
item Slovin, Janet

Submitted to: International Plant Growth Substance Association
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Gamma-glutamyl transpeptidases (GTases) are the only enzymes known to hydrolyze the unique N-terminal amide bonds of reduced glutathione,oxidized glutathione, and glutathione S-conjugates. Two GTases (I and II) with Km values for glutathione of 110 and 90 uM were purified 2,977-fold and 2,152-fold, respectively, from ripe tomato (Lycopersicon esculentum)pericarp. Both enzymes also hydrolyzed dipeptides and other tripeptides with N-terminal, gamma-linked glutamic acid,and the artificial substrates gamma-L-glutamyl-p-nitroanilide and gamma-L-glutamyl(7-amido-4-methylcoumarin). They transfer the glutamyl moiety to water or acceptor amino acids, including L-methionine, L-phenylalanine, L-tryptophan, or the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid. Gamma Gtase I and II were released from a wall and membrane fraction of a tomato fruit extract with 1.0M NaCl, suggesting that the are peripheral membrane proteins. They were further purified by acetone precipitation, affinity chromatography, and hydrophobic interaction chromatography. The two gamma GTases were resolved by concanavalin A (Con A) affinity chromatography, indicating that they are differentially glycosylated. The native and sodium dodecylsulfate-denatured forms of both enzymes showed molecular masses of 43kD.