Enzymic cross-linkage of monomeric extensin precursors in vitro. [Lycopersicon esculentum]

Journal Article · Fri Jul 01 04:00:00 EDT 1988 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.87.3.616· OSTI ID:7165154

Everdeen, D S; Kiefer, S; Willard, J J; Muldoon, E P; Dey, P M; Li, Xiongbiao; Lamport, D T.A. ^[1]

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1. Michigan State Univ., East Lansing (USA)

Rapidly growing tomato (Lycopersicon esculentum) cell suspension cultures contain transiently high levels of cell surface, salt-elutable, monomeric precursors to the covalently cross-linked extensin network of the primary cell wall. Thus, the authors purified a highly soluble monomeric extensin substrate from rapidly growing cells, and devised a soluble in vitro cross-linking assay based on Superose-6 fast protein liquid chromatography separation, which resolved extensin monomers from the newly formed oligomers within 25 minutes. Salt elution of slowly growing (early stationary phase) cells yielded little or no extensin monomers but did give a highly active enzymic preparation that specifically cross-linked extensin monomers in the presence of hydrogen peroxide, judging from: (a) a decrease in the extensin monomer peak on fast protein liquid chromatography gel filtration, (b) appearance of oligomeric peaks, and (c) direct electron microscopical observation of the cross-linked oligomers. The cross-linking reaction had a broad pH optimum between 5.5 and 6.5. An approach to substrate saturation of the enzyme required extensin monomer concentrations of 20 to 40 milligrams per milliliter. Preincubation with catalase completely inhibited the cross-linking reaction, which was highly dependent on hydrogen peroxide and optimal at 15 to 50 micromolar. They therefore identified the cross-linking activity as extensin peroxidase.

• DOE Contract Number: AC02-76ER01338
• OSTI ID: 7165154
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 87:3; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

551000* -- Physiological Systems
59 BASIC BIOLOGICAL SCIENCES
CELL CONSTITUENTS
CELL CULTURES
CELL MEMBRANES
CELL WALL
CHEMICAL REACTIONS
CROSS-LINKING
ENZYME ACTIVITY
ENZYMES
FOOD
FRUITS
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
IN VITRO
MEMBRANES
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PEROXIDASES
PEROXIDES
PHYSIOLOGY
PLANT CELLS
POLYMERIZATION
PRECURSOR
TOMATOES