Lignin peroxidase compound III. Mechanism of formation and decomposition

Journal Article · Mon Feb 05 04:00:00 EST 1990 · Journal of Biological Chemistry; (United States)

OSTI ID:6001603

Wariishi, Hiroyuki; Gold, M H ^[1]

---

1. Oregon Graduate Inst. of Science and Technology Center, Beaverton (United States)

Lignin peroxidase compound III (LiPIII) was prepared via three procedures: (a) ferrous LiP + O{sub 2} (LiPIIIa), (b) ferric LiP + O{sub 2}{sup {bar {sm bullet}}} (LiPIIIb), and (c) LiP compound II + excess H{sub 2}O{sub 2} followed by treatment with catalase (LiPIIIc). LiPIIIa, b, and c each have a Soret maximum at {approximately}414 nm and visible bands at 543 and 578 nm. LiPIIIa, b, and c each slowly reverted to native ferric LiP, releasing stoichiometric amounts of O{sub 2}{sup {bar {sm bullet}}} in the process. The LiPIII reversion reactions obeyed first-order kinetics with rate constants of {approximately}1.0 {times} 10{sup {minus}3} s{sup {minus}1}. In the presence of excess peroxide, at pH 3.0, native LiP, LiPII, and LiPIIIa, b, and c are all converted to a unique oxidized species (LiPIII*) with a spectrum displaying visible bands at 543 and 578 nm, but with a Soret maximum at 419 nm, red-shifted 5 nm from that of LiPIII. LiPIII* is bleached and inactivated in the presence of excess H{sub 2}O{sub 2} via a biphasic process. The fast first phase of this bleaching reaction obeys second-order kinetics, with a rate constant of 1.7 {times} 10{sup 1} M{sup {minus}1} s{sup {minus}1}. Addition of veratryl alcohol to LiPIII* results in its rapid reversion to the native enzyme, via an apparent one-step reaction that obeys second-order kinetics, with a rate constant of 3.5 {times} 10{sup 1} M{sup {minus}1} s{sup {minus}1}. Stoichiometric amounts of O{sub 2}{sup {bar {sm bullet}}} are released during this reaction. When this reaction was run under conditions that prevented further reactions, HPLC analysis of the products demonstrated that veratryl alcohol was not oxidized. These results suggest that the binding of veratryl alcohol to LiPIII* displaces O{sub 2}{sup {bar {sm bullet}}}, thus returning the enzyme to its native state. In contrast, the addition of veratryl alcohol to LiPIII did not affect the rate of spontaneous reversion of LiPIII to the native enzyme.

• DOE Contract Number: FG06-86ER13550
• OSTI ID: 6001603
• Journal Information: Journal of Biological Chemistry; (United States), Journal Name: Journal of Biological Chemistry; (United States) Vol. 265:4; ISSN JBCHA; ISSN 0021-9258
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
090900 -- Biomass Fuels-- Processing-- (1990-)
550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTROSCOPY
CARBOHYDRATES
CHEMICAL REACTIONS
DECOMPOSITION
DELIGNIFICATION
ELEMENTS
ENZYMES
LIGNIN
NONMETALS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
OXYGEN
PEROXIDASES
POLYSACCHARIDES
PROTEINS
SACCHARIDES
SPECTRA
SPECTROSCOPY
SYNTHESIS
VISIBLE SPECTRA
WOOD